Original Article
S-nitrosocaptopril nanoparticles as nitric oxide-liberating and transnitrosylating anti-infective technology

https://doi.org/10.1016/j.nano.2014.09.017Get rights and content

Abstract

Nitric oxide (NO), an essential agent of the innate immune system, exhibits multi-mechanistic antimicrobial activity. Previously, NO-releasing nanoparticles (NO-np) demonstrated increased antimicrobial activity when combined with glutathione (GSH) due to formation of S-nitrosoglutathione (GSNO), a transnitrosylating agent. To capitalize on this finding, we incorporated the thiol-containing ACE-inhibitor, captopril, with NO-np to form SNO-CAP-np, nanoparticles that both release NO and form S-nitrosocaptopril. In the presence of GSH, SNO-CAP-np demonstrated increased transnitrosylation activity compared to NO-np, as exhibited by increased GSNO formation. Escherichia coli and methicillin-resistant Staphylococcus aureus were highly susceptible to SNO-CAP-np in a dose-dependent fashion, with E. coli being most susceptible, and SNO-CAP-np were nontoxic in zebrafish embryos at translatable concentrations. Given SNO-CAP-np’s increased transnitrosylation activity and increased E. coli susceptibility compared to NO-np, transnitrosylation rather than free NO is likely responsible for overcoming E. coli’s resistance mechanisms and ultimately killing the pathogen.

From the Clinical Editor

This team of authors incorporated the thiol-containing ACE-inhibitor, captopril, into a nitric oxide releasing nanoparticle system, generating nanoparticles that both release NO and form S-nitrosocaptopril, with pronounced toxic effects on MRSA and E. coli in the presented model system.

Graphical Abstract

Previously, we demonstrated increased antimicrobial activity against E. coli with nitric oxide releasing nanoparticles (NO-np) + GSH, versus NO-np alone, due to formation of S-nitrosoglutathione (GSNO), a potent transnitrosylating agent. However, a suspension of NO-np + GSH would not be practical. In the current study, we incorporated captopril into a novel nanoparticle which can generate NO as well as S-nitrosocaptopril (SNO-CAP). In addition to sustained release of NO, SNO-CAP-np demonstrated sustained GSNO production in the presence of GSH and killed both E. coli and MRSA in a dose-dependent fashion, with a pronounced effect against E. coli.

  1. Download : Download high-res image (236KB)
  2. Download : Download full-size image

Section snippets

Synthesis of SNO-CAP nanoparticles

A modified tetramethylorthosilicate (TMOS)-based sol–gel method was used to prepare SNO-CAP-np as previously described.17 Briefly, TMOS (3 mL) was hydrolyzed with 1 mM HCl (0.6 mL) by sonication on an ice-bath. The hydrolyzed TMOS (3 mL) was added to a buffer mixture of 1.5 mL of 0.5% chitosan, 1.5 mL of polyethylene glycol (PEG) 400, and 24 mL of 50 mM phosphate (pH 7.4) containing 0.225 M nitrite and 0.28 M captopril. The mixture was left at room temperature overnight in the dark for polymerization. A

SNO-CAP-np size characterization

SNO-CAP-np size determined by scanning electron microscopy (SEM) is congruent with previous data in which our similarly designed NO-np was measured via transmission electron microscopy (TEM).17 While previous TEM preparations were imaged to show individual nanoparticles of 10 nm in diameter,17 our current SEM preparations yielded nanoaggregates of 60-80 nm in diameter (measured from 100 nanoaggregates). However, individual nanoparticles could be visualized within many of the nanoaggregates which

Discussion

Due to the continued threat of antibiotic resistance, it is necessary to pursue technologies that employ innovative, multi-mechanistic methods to kill bacteria and limit the chance for adverse events associated with their use. In the current study, SNO-CAP-np demonstrated sustained nitrosylation activity via production of GSNO in the presence of GSH, which was maintained at a steady concentration over an extended period of time. In addition, SNO-CAP-np released and maintained significant levels

References (29)

  • N.M. van Sorge et al.

    Methicillin-resistant Staphylococcus aureus bacterial nitric-oxide synthase affects antibiotic sensitivity and skin abscess development

    J Biol Chem

    (2013)
  • M.A. De Groote et al.

    NO inhibitions: antimicrobial properties of nitric oxide

    Clin Infect Dis

    (1995)
  • C. Bogdan

    Nitric oxide and the immune response

    Nat Immunol

    (2001)
  • A. Diefenbach et al.

    Requirement for type 2 NO synthase for IL-12 signaling in innate immunity

    Science

    (1999)
  • Cited by (12)

    • Roles and current applications of S-nitrosoglutathione in anti-infective biomaterials

      2022, Materials Today Bio
      Citation Excerpt :

      In addition, NO-np plus GSH completely inhibited P. aeruginosa within one day and accelerated healing of the infected wounds [107]. To take advantage of this finding, researchers incorporated thiol-containing captopril into NO-np to form SNO-CAP-np, which could release NO with S-nitrosocaptopril providing thiol to facilitate transnitrosylation (Fig. 5b) [108]. Upon exposure to GSH, SNO-CAP-np exhibited stronger transnitrosylation activity and increased GSNO formation compared to that of NO-np, and showed potent antimicrobial properties against E. coli and MRSA in a dose-dependent manner.

    • Challenging development of storable particles for oral delivery of a physiological nitric oxide donor

      2020, Nitric Oxide - Biology and Chemistry
      Citation Excerpt :

      An attractive alternative strategy mimicking the physiology could be to encapsulate high molecular weight S-nitrosothiols, which will generate GSNO in situ by transnitrosation of physiological GSH. Previous studies with encapsulation of S-nitroso-N-acetylcysteine [43] and S-nitroso-captopril [44] proved the effectiveness of this transnitrosation approach to elicit vasodilation or anti-infectious effects after parenteral or local administration, respectively. However, despite the lower encapsulation and duration of drug release with our Eudragit® particles, the release rate itself, around 150 pmol.

    • Free radical-releasing systems for targeting biofilms

      2020, Journal of Controlled Release
      Citation Excerpt :

      One of the modes of action of free radicals includes mediating host defense mechanisms [82] that stimulate the natural elimination of microbes. This process involves the high production of reactive oxygen species which leads to increased sensitivity of the immune cells to oxidative stress [83]. The major mechanisms of bacterial cell death initiated by reactive nitrogen and reactive oxygen species are nitrosative and oxidative stress, respectively.

    View all citing articles on Scopus

    Funding and Conflict of Interest: SLH acknowledges NIH grants ES017552-01A2, ES016896-01, P30 ES03850, T32 ES0007060, and AFRL FA8650-05-1-5041.

    JDN acknowledges National Institutes of Health/National Institute of Allergy and Infectious Diseases grant 1RC2A1087612-01.

    AJF acknowledges Dermatology Foundation Career Development Award and Janssen Biotech Research Grant.

    JMF, PN, and AJF are co-inventors of the technology described; however no financial conflict currently exists.

    View full text