Antimicrobial peptides (AMPs) are promising alternatives to antibiotics for treatment of antimicrobial resistant (AMR) bacterial infections. However, their narrow therapeutic window due to in vivo... Show moreAntimicrobial peptides (AMPs) are promising alternatives to antibiotics for treatment of antimicrobial resistant (AMR) bacterial infections. However, their narrow therapeutic window due to in vivo toxicity and limited stability hampers their clinical use. Here, we evaluated encapsulation of two amphiphilic AMPs, SAAP-148 and snake cathelicidin Ab-Cath, into oleyl-modified hyaluronic acid (OL-HA) nanogels to improve their selectivity index. The AMP-loaded OL-HA nanogels ranged 181–206 nm in size with a PDI of 0.2, highly negative surface charge (−47 to −48 mV) and moderate encapsulation efficiency (53–63%). The AMP-loaded OL-HA nanogels displayed similar activity in vitro as AMP solutions against AMR Staphylococcus aureus and Acinetobacter baumannii, with a dose-dependent effect over time. Importantly, the AMP-loaded OL-HA nanogels showed decreased cytotoxicity towards human erythrocytes and primary skin fibroblast, thereby improving the selectivity index of SAAP-148 and Ab-Cath by 2- and 16.8-fold, respectively. Particularly, the selectivity of Ab-Cath-loaded OL-HA nanogels has great clinical potential, with an index that reached ≥ 300 for S. aureus and ≥ 3000 for A. baumannii. These findings indicate that OL-HA nanogels are a promising drug delivery system to reduce the cytotoxicity of AMPs without substantially affecting their antimicrobial activity, thereby increasing their selectivity index and potential as therapeutics to combat AMR bacterial infections. Show less
Gent, M.E. van; Kiodsinska, S.N.; Severin, M.; Ali, M.; Doodewaerd, B.R. van; Bos, E.; ... ; Nibbering, P.H. 2023
The antimicrobial peptide Ab-Cath, is a promising candidate for development as treatment for antimicrobial resistant (AMR) bacterial infections. Future clinical use is hampered by Ab-Cath's... Show moreThe antimicrobial peptide Ab-Cath, is a promising candidate for development as treatment for antimicrobial resistant (AMR) bacterial infections. Future clinical use is hampered by Ab-Cath's cationic peptidic nature and limited therapeutic window. Here, we evaluated hyaluronic acid-based nanogels for encapsulation of Ab-Cath to circumvent these limitations. Using microfluidics, monodispersed anionic nanogels of 156–232 nm encapsulating >99 % Ab-Cath were prepared. Unprecedented, lyophilization using polyvinyl alcohol and dextran-40 provided Ab-Cath nanogel protection and allowed easy dose adjustment. Lyophilized and redispersed Ab-Cath nanogels were as effective as Ab-Cath solution in killing AMR Staphylococcus aureus, Acinetobacter baumannii and Escherichia coli in biological fluids, and in reducing S. aureus and A. baumanniibiofilms. Importantly, encapsulation of Ab-Cath in nanogels reduced Ab-Cath's cytotoxic effects on human fibroblasts by ≥10-fold. Moreover, cutaneous application of Ab-Cath nanogels eliminated bacteria colonizing 3D human skin. These findings affirm the use of nanogels to increase the selectivity index of antimicrobial peptides. Show less
Cancer vaccines are aimed at raising an immune responses aganist defined tumor antigens. The formulation of a vaccine has a direct impact on the potency of the immune response generated. Cancer... Show moreCancer vaccines are aimed at raising an immune responses aganist defined tumor antigens. The formulation of a vaccine has a direct impact on the potency of the immune response generated. Cancer vaccines require particular effort in their formulation, as the immune system has to overcome immune suppression exerted by the tumor. In this thesis, different formulations to enhance cancer vaccine efficacy were explored. In the first part it is shown how chemical conjugation of antigen and adjuvant in form synthetic Toll-like receptor ligands represent a strategy to enahnce vaccine potency. Next, it is presented how the loading of peptide antigens onto dextran nanogel contributes to increase the breadth of the immune response induced. Lastly, a new DNA vaccine containing multiple tumor neoantigens was explored as a platform for personalized cancer vaccines. Together, these studies display how the formulation of cancer vaccines can be modified and optimized to achieve stronger therapeutic efficacy in the clinic. Show less
