Immunocytochemical Distribution of Human PMN Elastase and Cathepsin-G in Dental Pulp

Abstract

Components of primary (azurophilic) granules of polymorphonuclear leukocytes (PMNs) have been implicated as important mediators in pulpal inflammation. This anatomical study used ultracryoimmunocytochemical techniques and characterized and contrasted the subcellular distributions of human PMN elastase (PMN-E), PMN cathepsin-G (PMN-CG), and alpha-2 macroglobulin (alpha-2M) in healthy and inflamed dental pulps. Inflamed pulpal tissue sections revealed an intense distribution of PMN-E in the extracellular domain throughout the collagen matrix. PMN-E was also localized in the perinuclear cytoplasm of PMNs and distributed in a random fashion. PMN-CG was localized intensely in the intracellular granules of PMNs and observed moderately within the extracellular matrix. Healthy pulpal tissues exposed to PMN-E and PMN-CG antibodies revealed no evidence of PMN infiltration and no specific labeling. alpha-2M, a natural serum inhibitor of PMN-E and PMN-CG, was distributed in an intense fashion within the intravascular compartments of both inflamed and healthy pulpal samples. Immunogold-labeling for alpha-2M was observed in moderate amounts within the extravascular domain of inflamed pulpal samples but only in mild amounts within the same area of healthy tissues. These results suggest that PMN-E and PMN-CG are released to the extracellular matrix of irreversibly inflamed teeth, enabling them to facilitate pulpal connective tissue destruction. Conversely, moderate extravascular labeling for alpha-2M within inflamed samples suggests a physiological attempt at inhibiting the pulpal connective tissue destruction mediated by human PMN-E and PMN-CG.

Role of Polymorphonuclear Neutrophils in the Clearance of Enterococcus faecalis Derived from Saliva and Infected Root Canals

“…Increased levels of several proteolytic enzymes such as elastase, cathepsin G, and MMP-8 released by PMNs in pulpitis and chronic apical periodontitis have been reported (9,10). In this study, TNF-a, IL-1a, and MMP-8 were clearly up-regulated when PMNs were incubated with E. faecalis in vitro (Fig.…”

“…Polymorphonuclear neutrophils (PMNs) are in general regarded as the most efficient first line of defense cells against invading microorganisms. PMNs play an important role in the early control of acute bacterial infections by killing bacterial pathogens through powerful oxidative and nonoxidative mechanisms and through the production of inflammatory and immunoregulatory cytokines and chemokines, such as tumor necrosis factor a (TNF-a), interleukin-1 (IL-1), and proteolytic enzyme, such as matrix metalloproteinases-8 (MMP-8, neutrophil collagenase) (8)(9)(10). These molecules lead to the influx and activation of PMNs and macrophages at the site of infection, which are important first steps in the development of inflammation (11).…”

The Expression of Macrophage and Neutrophil Elastases in Rat Periradicular Lesions

“…A positive relationship exists between pulpitis and the increase of neutrophil elastase activity in humans (23). Polymorphonuclear leukocyte elastase was observed in the periapical tissue of patients clinically diagnosed as having irreversible pulpitis (24). Neutrophil elastase is detected in the periodontal ligament of patients with periodontitis (33).…”

“…This protease has wide substrate specificity and has strong competency in degrading a variety of the proteins including elastin (22). There is a possibility that it evokes the severe tissue destruction seen in pulpitis (23) and periradicular lesions (24). In human periapical disease, neutrophil elastase levels of periapical exudates associated with clinical symptoms (25) and there may be a possibility that it serves as a diagnostic marker (26).…”

Molecular diagnostics in endodontics

“…Studies on entire pulp tissue consistently showed that PMN‐related enzymes such as elastase and cathepsin G and MMP‐9 are elevated in clinically inflamed pulps compared to healthy dental pulps. Histologically, the presence of these enzymes or their respective mRNAs is strongly correlated to the inflammatory infiltrate . The same is true for IL‐8, the main neutrophil chemoattractant.…”