Highly Efficient Oral Iguratimod/Polyvinyl Alcohol Nanodrugs Fabricated by High-Gravity Nanoprecipitation Technique for Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA), a systemic autoimmune disease, poses a significant human health threat. Iguratimod (IGUR), a novel disease-modifying antirheumatic drug (DMARD), has attracted great attention for RA treatment. Due to IGUR's hydrophobic nature, there's a pressing need for effective pharmaceutical formulations to enhance bioavailability and therapeutic efficacy. The high-gravity nanoprecipitation technique (HGNPT) emerges as a promising approach for formulating poorly water-soluble drugs. In this study, IGUR nanodrugs (NanoIGUR) are synthesized using HGNPT, with a focus on optimizing various operational parameters. The outcomes revealed that HGNPT enabled the continuous production of NanoIGUR with smaller sizes (ranging from 300 to 1000 nm), more uniform shapes, and reduced crystallinity. In vitro drug release tests demonstrated improved dissolution rates with decreasing particle size and crystallinity. Notably, in vitro and in vivo investigations showcased NanoIGUR's efficacy in inhibiting synovial fibroblast proliferation, migration, and invasion, as well as reducing inflammation in collagen-induced arthritis. This study introduces a promising strategy to enhance and broaden the application of poorly water-soluble drugs.

Iguratimod inhibits osteoclastogenesis by modulating the RANKL and TNF-α signaling pathways

BACKGROUND

Iguratimod, a small molecular drug, has been proven to have effective bone protection for treatment of patients with bone loss-related diseases, such as rheumatoid arthritis (RA). However, the exact bone protective mechanism of iguratimod remains to be determined. The purpose of this study was to better explore the underlying mechanism of bone protection of iguratimod.

METHODS

Bone marrow monocytes from C57/BL6 mice were stimulated with either RANKL or TNF-α plus M-CSF. The effects of iguratimod on morphology and function of osteoclasts were confirmed by TRAP staining and bone resorption assay, respectively. The expression of osteoclast related genes was detected by RT-PCR and the activation of signal pathway was detected by Western blotting. We used rodent models of osteoporosis (ovariectomy) and of arthritis (modified TNF-α-induced osteoclastogenesis) to evaluate the osteoprotective effect of iguratimod in vivo.

RESULTS

Iguratimod potently inhibited osteoclast formation in a dose-dependent manner at the early stage of RANKL-induced osteoclastogenesis, whereas iguratimod had no effect on M-CSF-induced proliferation and RANK expression in bone marrow monocytes. Bone resorption was significantly reduced by both early and late addition of iguratimod. Administration of iguratimod prevented bone loss in ovariectomized mice. The blockage of osteoclastogenesis elicited by iguratimod results from abrogation of the p38、ERK and NF-κB pathways induced by RANKL. Importantly, Iguratimod also dampened TNF-α-induced osteoclastogenesis in vitro and attenuated osteoclasts generation in vivo through disrupting NF-κB late nuclear translocation without interfering with IκBα degradation.

CONCLUSIONS

Iguratimod not only suppresses osteoclastogenesis by interfering with RANKL and TNF-α signals, but also inhibits the bone resorption of mature osteoclasts. These results provided promising evidence for the therapeutic application of iguratimod as a unique treatment option against RA and especially in prevention of bone loss.