Liposomes-In-Hydrogel Delivery System Enhances the Potential of Resveratrol in Combating Vaginal Chlamydia Infection

Abstract

Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections and causes serious reproductive tract complications among women. The limitations of existing oral antibiotics and treatment of antimicrobial resistance require alternative treatment options. We are proposing, for the first time, the natural polyphenol resveratrol (RES) in an advanced delivery system comprising liposomes incorporated in chitosan hydrogel, for the localized treatment of C. trachomatis infection. Both free RES and RES liposomes-in-hydrogel inhibited the propagation of C. trachomatis in a concentration-dependent manner, assessed by the commonly used in vitro model comprising McCoy cells. However, for lower concentrations, the anti-chlamydial effect of RES was enhanced when incorporated into a liposomes-in-hydrogel delivery system, with inhibition of 78% and 94% for 1.5 and 3 µg/mL RES, respectively for RES liposomes-in-hydrogel, compared to 43% and 72%, respectively, for free RES. Furthermore, RES liposomes-in-hydrogel exhibited strong anti-inflammatory activity in vitro, in a concentration-dependent inhibition of nitric oxide production in the LPS-induced macrophages (RAW 264.7). The combination of a natural substance exhibiting multi-targeted pharmacological properties, and a delivery system that provides enhanced activity as well as applicability for vaginal administration, could be a promising option for the localized treatment of C. trachomatis infection.

Keywords: Chlamydia trachomatis; antimicrobial; chitosan; hydrogel; liposomes; resveratrol; vaginal therapy.

Figure 1

Sustained in vitro resveratrol (RES) release (n = 3). RES release from liposomes and liposomes-in-hydrogel compared to the respective controls, assessed by a spiral release system for 8 h. Results are expressed as percentage mean ± SD. * RES in propylene glycol.

Figure 2

RES formulations reduce the number of C. trachomatis-infected cells. Two hours after McCoy cells were infected, the cells were left untreated or added treatment (RES concentrations of 1.5, 3 or 6 µg/mL for (A–C), respectively). The effect on bacterial survival was evaluated by staining of inclusions. The figure shows representative pictures of the antimicrobial effect of azithromycin (AZT) (2), free RES (control; RES in propylene glycol) (3), RES in hydrogel (4), RES liposomes (5) and RES liposomes-in-hydrogel (6), compared to the negative control (1) where no treatment was added. All pictures were taken with same magnification (10×).

Figure 3

Effect of RES formulations on C. trachomatis in vitro (n = 4). The values are based on images presented in Figure 2. Number of inclusions for the treated and the non-treated cells were compared. * RES in propylene glycol, a,b,c p < 0.05, d,e,f p < 0.005, g,h,i p < 0.001.