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. 2012:7:3929-38.
doi: 10.2147/IJN.S33835. Epub 2012 Jul 23.

Improved biological properties and hypouricemic effects of uricase from Candida utilis loaded in novel alkaline enzymosomes

Qun-You Tan  1 , Jing-Qing Zhang, Na Wang, Hong Yang, Xiaoling Li, Hua-Rong Xiong, Jian-Yong Wu, Chun-Jing Zhao, Hong Wang, Hua-Feng Yin
Affiliations

Improved biological properties and hypouricemic effects of uricase from Candida utilis loaded in novel alkaline enzymosomes

Qun-You Tan et al. Int J Nanomedicine. 2012.

Abstract

Objective: Previous studies on various enzymosomes (functional lipid vesicles encapsulating an enzyme) have been mostly carried out in vitro and have focused on preserving catalytic activity and improving the stability of the enzyme. Until now, few studies have focused on their in vivo fate. Similarly, although we have previously reported the increased in vitro uricolytic activity (about 2.2 times higher than that of free uricase, or three times higher than that of PEGylated uricase, Puricase(®), under physiological pH and temperature) and improved stability of the novel alkaline enzymosomes (functional lipid vesicles encapsulating uricase from Candida utilis: uricase-containing lipid vesicles, UOXLVs), it is still necessary to study the biological properties and hypouricemic effects of UOXLVs in vivo.

Methods: The enzyme kinetics, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary safety of UOXLVs were evaluated.

Results: The Michaelis constant (K(m)) value of the UOXLVs was slightly lower than that of the free enzyme. The enzyme release from the UOXLVs lasted over 12 hours and their circulation half-life was about sevenfold longer than that of the free uricase. Meanwhile, the UOXLVs had a 22-fold increase in the area under the curve compared with the free uricase. Furthermore, it took less than 3 hours for the UOXLVs to lower the plasma uric acid concentration from a high to a normal level, compared with 6 hours for the free uricase. In addition, the UOXLVs had much less immunogenicity than free uricase and were well tolerated by all animals throughout the observation period.

Conclusion: The UOXLVs markedly improved the biological properties and enhanced the hypouricemic effects of uricase in vivo.

Keywords: alkaline enzymosomes; biological properties; hypouricemic effect; in vivo; uricase.

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Figures

Figure 1
Figure 1
Schematic diagram of uricase-containing lipid vesicles (UOXLVs) catalyzing the transformation of uric acid into allantoin.
Figure 2
Figure 2
Lineweaver–Burk profiles of the uricase-containing lipid vesicles (UOXLVs) and free uricase (n = 3).
Figure 3
Figure 3
Time courses of the remaining activity of the uricase-containing lipid vesicles (UOXLVs) and free uricase in the presence of plasma (closed squares and triangles, respectively).
Figure 4
Figure 4
Plasma uricase activity versus time profiles after intravenous administration of uricase-containing lipid vesicles (UOXLVs) (closed squares) and free uricase (open squares) in rats. Note: Each point represents the mean ± standard deviation (n = 6).
Figure 5
Figure 5
The plasma uric acid concentration versus time profiles after intravenous injection of the solvent (normal group, closed squares), hypoxanthine and oxonic acid (hyperuricemia model group, open squares), free uricase (closed triangles), and uricase-containing lipid vesicles (UOXLVs) (open triangles) in rats. The plasma uric acid concentration was determined by uric acid assay kit. Note: Data are expressed as mean ± standard deviation (n = 6).
Figure 6
Figure 6
Immunogenicity test results. (A) Antisera dilution ratio; (B) antibody titer. Note: The data represent the mean ± standard deviation (n = 6). Abbreviation: UOXLVs, uricase-containing lipid vesicles.
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