Unveiling the Immunostimulatory Potential of the HSPA1A Mini-Chaperones Compared to the HSPA1A and HSP27 Chaperones: In Silico and In Vitro Insights for Vaccine Development

Molecular chaperones known as heat shock proteins (HSPs) are evolutionarily conserved and are critical in regulating immune system functions. To assess the immunostimulatory potential of HSPs, we employed advanced computational and experimental techniques. Bioinformatics tools were employed to analyze and confirm the physicochemical characteristics of the full-length HSPA1A, the fragments of HSPA1A known as minichaperones (C-terminal region of HSPA1A: CHSPA1A and N-terminal region of HSPA1A: NHSPA1A), and the full length HSP27, confirming their advantageous properties and structural integrity through 3D refinement and validation. Docking studies revealed significant interactions of HSPs with CD91 and TLR4 receptors respectively, notably a strong and stable binding of the full length HSPA1A and CHSPA1A with CD91. Molecular dynamics simulations were conducted to confirm the structural stability of the complexes formed between HSPs and CD91. Immunological simulations demonstrated robust and stable responses from both innate and adaptive immune cells against HSPs. All HSPs were produced in E. coli, isolated via Ni-NTA affinity chromatography, and subsequently utilized to stimulate immune cells from mice in vitro. The results showed significant secretion of TNF-α and IFN-γ in comparison to IL-10, indicating a directed T-helper 1 (cellular) immunity. The in silico and in vitro findings represented that HSPA1A and then CHSPA1A resulted in significantly greater TNF-α secretion in splenocytes co-cultured with the pulsed DCs compared to NHSPA1A and HSP27, suggesting their significant role in activating adaptive immunity. In contrast, macrophages exhibited an increased TNF-α secretion in response to HSP27, suggesting its involvement in modulating innate inflammatory processes. Understanding these differences can help in designing more effective immunotherapies.