RESUMO
Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine and atypical chemokine with a key role in inflammatory diseases including atherosclerosis. Key atherogenic functions of MIF are mediated by noncognate interaction with the chemokine receptor CXCR2. The MIF N-like loop comprising the sequence 47-56 is an important structural determinant of the MIF/CXCR2 interface and MIF(47-56) blocks atherogenic MIF activities. However, the mechanism and critical structure-activity information within this sequence have remained elusive. Here, we show that MIF(47-56) directly binds to CXCR2 to compete with MIF receptor activation. By using alanine scanning, essential and dispensable residues were identified. Moreover, MIF(cyclo10), a designed cyclized variant of MIF(47-56), inhibited key inflammatory and atherogenic MIF activities inâ vitro and inâ vivo/ex vivo, and exhibited strongly improved resistance to proteolytic degradation in human plasma inâ vitro, thus suggesting that it could serve as a promising basis for MIF-derived anti-atherosclerotic peptides.
Assuntos
Fatores Inibidores da Migração de Macrófagos/química , Peptídeos Cíclicos/metabolismo , Receptores de Interleucina-8B/metabolismo , Sequência de Aminoácidos , Animais , Adesão Celular , Fluoresceínas/química , Células HEK293 , Humanos , Leucócitos/química , Leucócitos/citologia , Leucócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Peptídeos Cíclicos/sangue , Peptídeos Cíclicos/química , Ligação Proteica , Estabilidade Proteica , Receptores de Interleucina-8B/antagonistas & inibidores , Espectrometria de Fluorescência , Ácidos Sulfônicos/químicaRESUMO
Amyloid self-assembly is linked to numerous devastating cell-degenerative diseases. However, designing inhibitors of this pathogenic process remains a major challenge. Cross-interactions between amyloid-ß peptide (Aß) and islet amyloid polypeptide (IAPP), key polypeptides of Alzheimer's disease (AD) and type 2 diabetes (T2D), have been suggested to link AD with T2D pathogenesis. Here, we show that constrained peptides designed to mimic the Aß amyloid core (ACMs) are nanomolar cross-amyloid inhibitors of both IAPP and Aß42 and effectively suppress reciprocal cross-seeding. Remarkably, ACMs act by co-assembling with IAPP or Aß42 into amyloid fibril-resembling but non-toxic nanofibers and their highly ordered superstructures. Co-assembled nanofibers exhibit various potentially beneficial features including thermolability, proteolytic degradability, and effective cellular clearance which are reminiscent of labile/reversible functional amyloids. ACMs are thus promising leads for potent anti-amyloid drugs in both T2D and AD while the supramolecular nanofiber co-assemblies should inform the design of novel functional (hetero-)amyloid-based nanomaterials for biomedical/biotechnological applications.