D1.428 - Immunomodulation of human PBMCs by peptide amphiphiles

Advanced biomaterials for tissue regeneration are engineered to prevent fibrosis and to modulate the local immune microenvironment to promote functional tissue repair. Peptide amphiphiles (PAs) constitute a versatile class of supramolecular biomaterials that spontaneous self-assembly into nanofibrous networks resembling natural matrix components. In this study, we investigated the immunomodulatory properties of a glutamic acid-based peptide amphiphile (PA-E3), and 2 sequence variations, TGF-β1-binding PA-T3 and BMP-2-binding PA-B3. These peptide amphiphiles spontaneously form hydrogels, which were exposed to primary human peripheral blood mononuclear cells (PBMCs).

PBMCs were used to assess biocompatibility and immune responses. After 48-hour exposure, PBMC viability and spontaneous proliferation were evaluated, together with anti-CD3 and anti-CD28 mAb-stimulated proliferation of CD4⁺ T cells, CD8⁺ T cells and CD19⁺ B cells. Mechanistic insights were obtained through transcriptomic (RNA-seq) analysis.

Both functionalized PAs exhibited biocompatibility with PBMC viability and spontaneous proliferation rates statistically indistinguishable from the unmodified PA-E3. PA-E3, PA-T3, and PA-B3 induced comparable levels of suppression in stimulated PBMCs, indicating that the observed effect reflects a shared property of the PA scaffold and that PA-T3 and PA-B3 do not confer additional immunosuppressive activity. Transcriptomic profiling revealed that PA-B3 induced minimal transcriptional alterations, with 47 differentially expressed genes, whereas PA-T3 elicited a broader transcriptional response involving 366 differentially expressed genes. Pathway enrichment analysis indicated that PA-T3 modulate biological processes associated with chemotaxis, leukocyte migration, angiogenesis, regulation of the inflammatory response, fibrinolysis, extrinsic apoptotic signaling pathway, cell-cell adhesion, leukocyte proliferation and regulation of ossification.

These results highlight the selective immune-regulatory potential of PA-T3, supporting the concept that epitope-specific PAs can function as immune-instructive scaffolds capable of promoting a pro-regenerative microenvironment favorable for bone repair.