Determining the presence and origin of collagenase in human periapical lesions

Bioactive chitosan nanoparticles and photodynamic therapy inhibit collagen degradation in vitro

INTRODUCTION

Collagen is the major structural protein of human dentin. Degradation of collagen by bacterial enzymes can facilitate microbial penetration, compromise structural/interfacial integrity, and lower resistance to fracture of dentin. We evaluated the ability of photodynamic therapy (PDT), bioactive chitosan nanoparticles (CSnp), or PDT in combination with CSnp to inhibit bacterial collagenase-mediated degradation of collagen.

METHODS

Rat type 1 fibrillar collagen matrices were untreated or treated with 2.5% glutaraldehyde (GD), 2.5% GD followed by 1% CSnp, 1% CSnp, PDT (rose bengal activated with 540 nm light at 40 J/cm(2)), or 1% CSnp followed by PDT. Samples, except those used as untreated controls, were exposed to Clostridium histolyticum collagenase (125 CDU/mL) for 24 hours. The soluble digestion products were assessed by hydroxyproline assay, and the remaining adherent collagen was quantified by picrosirius red staining. Fourier transform infrared spectroscopy, immunoblotting, and scanning electron microscopy were used to study the interaction between CSnp/PDT with type 1 collagen. The data were analyzed by 1-way analysis of variance and post hoc Tukey test.

RESULTS

As assessed by hydroxyproline release into the medium, collagen treated with CSnp, PDT, or a combination of CSnp and PDT exhibited less degradation than untreated controls (3.6-fold, 1.7-fold, and 7.9-fold reduction, respectively; P < .05). Compared with all other treatments, GD-treated collagen was the most resistant to collagenolytic degradation (239.6-fold reduction, P < .05). The abundance of post-treatment residual collagen, as measured by picrosirius red staining, was inversely related to the extent of collagen degradation. Analysis of collagen cross-links with Fourier transform infrared spectroscopy showed that PDT or GD treatments enhanced collagen cross-linking. Immunoblotting of sedimented CSnp indicated that CSnp and collagenase bound with low affinity. However, CSnp-bound collagenase showed a significant reduction in collagenolytic activity compared with controls (P < .05).

CONCLUSIONS

Combined photochemical cross-linking of rat tail collagen by PDT and binding to CSnp inhibit collagenolytic activity.

Effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) on the healing of rat periapical lesions

To investigate the effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) in the root canal treatment of apical periodontitis, we studied the healing process of experimentally induced periapical lesions in rats by using immunohistochemical methods. With a topical application of a combination of ofloxacin and FN-439 following experimentally induced periapical lesions, both neutrophils and macrophages became significantly decreased in number, while active cementogenesis and extensive bone formation were seen in the periapical region. However, the use of ofloxacin alone also demonstrated a beneficial effect on periapical inflammation and healing. Therefore, it is suggested that ofloxacin is powerful against bacterial infection whether FN-439 is added. The only observed effect of a combination of ofloxacin and FN-439 is that it may more effectively inhibit osteoclastic bone resorption and activate the remodeling of the apical periodontal tissue if this combined medicament is used in a stage of active bone destruction characterized by high production of tissue collagenase.

Biochemical and histochemical analysis of the enzyme arylsulfatase in human lesions of endodontic origin

Lesions of endodontic origin are areas of inflammatory response which occur as a result of untreated disease process within the root canal system. Lysosomal hydrolytic arylsulfatase A and B have been identified as major enzymes initiating and propagating bone loss by degrading chondroitin-4-sulfate. The purpose of this investigation was to examine human lesions of endodontic origin for the presence of arylsulfatase A and B. Fifteen periapical lesions were obtained at the time of periapical surgery. The lesions were analyzed for the presence of arylsulfatases using the spectrophotometer by monitoring the liberated 4-nitrocatechol at 515-nm wavelength. The same lesions were examined histochemically using the electron microscope. Five control samples from healthy periodontal ligament were evaluated in a similar manner. The results showed higher levels of arylsulfatase A in lesions than in control tissues, and marked activity of arylsulfatase B in lesions, whereas no activity of this enzyme was detected in the control specimen. Histochemically, all lesions showed positive staining for enzyme activity, whereas the controls were negative. These findings indicate that arylsulfatase A and B play a role in the pathogenesis of human lesions of endodontic origin.