(294g) Enhanced Stabilization of Cytokines for Nanoparticle Delivery Applications

Cytokines are small proteins that are crucial to cell signaling, making them useful as therapeutic agents. However, cytokines must be localized to specific areas of the body to minimize harmful side effects such as systemic inflammation or cytokine storm, requiring targeted drug delivery methods. Polymeric micro- and nanoparticles have emerged in recent years as promising vehicles for improving the delivery of cytokines to diseased tissues (e.g., solid tumors).^1,2 However, cytokines are also sensitive to denaturation, which may limit the number of methods available to formulate micro-/nanoparticles, depending on the cytokines being delivered. A clear molecular understanding of the interactions between the relevant proteins and solvents used in these systems could enable the improved design of cytokine-encapsulating particles for delivery to, and function within, various tissue microenvironments.

We utilized an integrated computational and experimental approach for studying the governing mechanisms by which a representative cytokine (interleukin-12; IL-12) is protected from denaturation by a protein stabilizer (bovine serum albumin; BSA) at an organic solvent-water interface found in some nanoparticular formulations. Specifically, we investigated key protein-protein interactions between IL-12 and BSA. We simulated these components both in water and in the presence of a water/dichloromethane (DCM) interface to mimic our double emulsion formulation method. Briefly, we observed that: (i) IL-12 partially denatures near the water/DCM interface, and (ii) IL-12 denaturation is reduced in the presence of BSA. Experimentally, we found that limited cytokine (<1% of loaded IL-12) can be encapsulated in particles without a protein stabilizer. Conversely, if BSA is added to the aqueous phase in molar excess to IL-12 and sufficient time is allowed for binding, elevated levels of cytokine can be encapsulated. Findings from this work have implications in establishing design principles to stabilize cytokines into polymeric particles for robust delivery to diseased tissues, enhancing their use as therapeutic agents for treating disease.

References

[1] Zhao, Z. et al. “Systemic tumour suppression via the preferential accumulation of erythrocyte-anchored chemokine-encapsulating nanoparticles in lung metastases”, Nat Biomed Eng, 2021, 5, 441–454.

[2] Zhao, Z. et al., “Erythrocyte leveraged chemotherapy (ELeCt): Nanoparticle assembly on erythrocyte surface to combat lung metastasis”, Sci Adv, 2019, 5, eaax9250.