Hyaluronic acid dissolving microneedle patch-assisted acupoint transdermal delivery of triptolide for effective rheumatoid arthritis treatment

Abstract

Triptolide (TP), a major active component of the herb Tripterygium wilfordii Hook F, has been shown excellent pharmacological effects on rheumatoid arthritis. However, TP is prone to causing severe organ toxicity, which limits its clinical application. In recent years, microneedle technology has provided a new option for the treatment of arthritis due to its advantages of efficient local transdermal drug delivery. In this study, we constructed a microneedle platform to deliver TP locally to the joints, thereby enhancing TP penetration and reducing systemic toxicity. Additionally, we investigated whether acupoint drug delivery can produce a synergistic effect of needles and drugs. First, TP was loaded into microneedles using polyvinylpyrrolidone and hyaluronic acid as matrix materials. Next, we established a rat adjuvant-induced arthritis (AIA) model to evaluate the therapeutic effect of TP-loaded microneedles. The experiments showed that TP-loaded microneedles alleviated the AIA rats' inflammatory response, joint swelling, and bone erosion. However, there was no significant difference in the therapeutic effect observed in the acupoint and non-acupoint administration groups. In conclusion, TP-loaded microneedles have the advantages of safety, convenience, and high efficacy over conventional administration routes, laying a foundation for the transdermal drug delivery system-based treatment of rheumatoid arthritis.

Keywords: Hyaluronic acid microneedle; Rheumatoid arthritis; Triptolide.

Fig. 1

Schematic showing the mechanisms outline diagram of a microneedle loaded with Triptolide for treating rheumatoid arthritis. Created with BioRender.com.

Fig. 2

Characterization of TP-MNs. (A) Schematic flow diagram of the preparation of TP-NMs. (B) Photograph of representative TP-MNs patch. (C) Lateral view of TP-MNs under an optical microscope, observation magnification of 10*40X. (D) Scanning electron microscope images of TP-MNs at different magnifications. (E) Side view of the 3D reconstruction of TP-MNs image by CLSM. Created with BioRender.com.

Fig. 3

Investigation of several key properties of TP-MNs. (A) Force-displacement curves show the mechanical properties of microneedles with different formulations. (B) Dissolution of TP-MNs at specified time points after application to rat skin in vivo. Observation magnification of 10*40X. (C) In vitro release profiles of TP-MNs and free TP during 48 h (n = 3). (D) Percentage of holes created and insertion depth of TP-MNs in ParafilmM layers. (E) H&E staining of skin sections to observe the depth of insertion of TP-MNs. (F) Recovery of rat skin at different times after application of TP-MNs. (G) Confocal micrographs of optical parts of rat skin at different depths in vivo insertion, the penetration depth was from the skin surface to a depth of 108 μm. Additionally, the representation of the three-dimensional structure generated by the insertion of FITC-loaded MNs.

Fig. 4

In vivo therapeutic effects of TP-MNs on AIA models. (A) Establishment of dosing intervals by CLSM. (B) Schematic diagram of the establishment and treatment of the AIA rat model. (C–E) Body weight alterations, arthritis scores and right hind paw thickness in AIA rats (*p < 0.05, **p < 0.01, ***p < 0.001). (F) Typical images of swelling in the right hind paws of rats were taken every five days after drug administration.

Fig. 5

Histopathological analysis of rat ankle joints. (A,B) Histopathological changes of the ankle joint and local inflammatory cell infiltration analyzed by H&E staining. (C) The degree of articular cartilage degeneration of the ankle joint was shown by safranin O-fast green staining in each group. (D) Histopathological score of rats (n = 6).

Fig. 6

Expression of inflammatory factors in the rat ankle joint detected by immunohistochemistry. (A) Micrographs of immunohistochemical sections of IL-1β、IL-6、TNF-α. (B) Semi-quantitative statistical analysis of the percentage of immunohistochemical positivity for IL-1β, IL-6, and TNF-α using Image J (n = 6, five areas were sampled for each sample).

Fig. 7

Micro-CT scanning images of rat ankle joints. (A) Three-dimensional scanning analysis images and (B) two-dimensional cross-section image analysis of rat ankle joints.