Multidimensional visualization of healthy and sensitized rabbit knee tissues by means of confocal microscopy

This study combines several fluorescence detection methods to distinguish structural features of the synovium and cartilage tissues and to visualize the localization of endogenous porphyrins in the sensitized tissues. Specimens of synovium and cartilage tissues obtained from rabbits with antigen-induced monoarthritis after intra-articular 5-aminolevulinic acid methyl ester injection and those from healthy rabbits were investigated ex vivo by means of fluorescence spectroscopy, fluorescence intensity, and lifetime microscopy. The presence of endogenous porphyrins was confirmed with the fluorescence spectra measured on sliced sensitized specimens. Application of the lifetime-gating method on fast fluorescence lifetime imaging microscopy images, allowed separate visualization of tissue structures possessing different average lifetimes. The presence of the structures has been validated by histopathological imaging based on conventional rapid hematoxylin–eosin staining of the specimens. The fluorescence lifetime of endogenous protoporphyrin IX has been assessed and employed for visualization of sensitized tissues.

Induction of protoporphyrin IX in patient-derived synoviocytes, cartilage explants and chondrons after application of 5-aminolevulinic acid or its methyl ester

OBJECTIVE

To compare the accumulation of protoporphyrin IX between synoviocytes of patients with rheumatoid arthritis (RA) or osteoarthritis (OA) and cartilage explants (CE) as well as chondrons of patients with OA after the application of 5-aminolevulinic acid (ALA) or its methyl ester (ALA-Me).

MATERIALS AND METHODS

Samples of synovial and cartilage tissues were obtained from joint replacement surgeries. The accumulation of PpIX was determined by measuring fluorescence spectra from 2 × 10(5) synoviocytes or chondrons suspended in a glass tube or directly from CE surface after 2, 4, 8 and 24h of incubation with ALA or ALA-Me.

RESULTS

No differences were found between the average fluorescence intensity values of PpIX in synoviocytes of patients with RA and OA. These values were non-significantly higher after incubation with ALA in comparison with ALA-Me at almost all time points. The average fluorescence intensity of PpIX in CE and chondrons was about ten times lower than in synoviocytes. The presence of preparation of hyaluronic acid (HA) significantly enhanced PpIX induction in chondrons versus treatment only with ALA.

CONCLUSIONS

A potential for the selective synovial sensitization with endogenous PpIX in comparison with cartilage tissue has been demonstrated in vitro after application of ALA or ALA-Me.

Effect of gold nanoparticles in the treatment of established collagen arthritis in rats

BACKGROUND AND OBJECTIVE

The role of gold nanoparticles (AuNPs) in the treatment of autoimmune diseases remains vague. Therefore, the aim of this study was to determine the effect of AuNPs in the treatment of rats with established collagen-induced arthritis (CIA).

MATERIAL AND METHODS

A total of 24 Wistar male rats with established CIA were used. AuNPs measuring 13-nm and 50-nm were prepared according to standard procedures, and their size was determined using transmission electron microscopy. These gold particles were injected intra-articularly 5 times a week, 12 injections in total. Body and organ weight, arthritic profiles based on paw swelling, histological changes in the joints and internal organs, blood indices, and serum oxidative products were investigated.

RESULTS

An examination of the course of the experimental disease and a subsequent histological analysis as well as hematological studies revealed a nontoxic effect of AuNPs on the vital organs. The treatment of the rats with established CIA by 13-nm and 50-nm gold nanoparticles decreased joint swelling by 49.7% (P<0.002) and 45.03% (P<0.01), respectively. That corresponded to the decrease in statistically significant histological changes in articular tissues. AuNPs showed their antioxidant effect by increasing the level of antioxidant enzyme catalase.

CONCLUSIONS

The continuous intra-articular administration of AuNPs not only reduced the inflammation, joint swelling, and development of polyarthritis, but also reduced histological changes in articular tissues without toxic effects on the internal organs. The results obtained disclose the role of AuNPs as antioxidant agents.