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Morphology of polymorphonuclear neutrophils during periodontal disease in the cynomolgus monkey
Abstract:
The polymorphonuclear neutrophil (PMN) appears to be an important cell in the protection of the host from pathogenic periodontal micro-organisms. The purpose of the present histological studies was to observe the emigration of the PMN from the gingival vessels to the periodontal pocket during gingivitis and ligature-induced periodontitis in the cynomolgus monkey. 2 adult female monkeys were treated by application of a silk ligature around selected posterior teeth. After 9 weeks, the monkeys were perfused and block sections of both ligated (early periodontitis) and non-ligated (gingivitis) sites were obtained, cut into smaller blocks containing a single interdental area (N = 15 for periodontitis, N = 5 for gingivitis) and processed for light and electron microscopic observations. Morphologically, no differences in PMNs between gingivitis and periodontitis were observed and therefore the following description applies to both disease states. In the vessels, the endothelial cells appeared to be actively involved in PMN emigration, maintaining long processes which surrounded the PMNs. Within the connective tissue, the PMNs maintained their typical morphology which included polylobated nuclei and numerous lysosomal granules. Many intact PMNs were observed intercellularly within the connective tissue and the epithelium. Within the periodontal pocket, a multilayer of PMNs surrounded the plaque mass. Cells with numerous bacteria-containing phagolysosomes were observed with increasing frequency as they approached the plaque. Deeper within the bacterial deposit, PMNs were seen in varying stages of degeneration. These histologic studies, when interpreted in the light of reports of severe, rapidly-progressive periodontitis in patients with PMN disorders, suggest that the interaction of PMNs with bacterial plaque may serve to maintain a defensive boundary which protects the host tissues from irreversible destruction.
Insights
Polymorphonuclear neutrophils (PMNs) are crucial for defending against periodontal pathogens. These immune cells migrate to the periodontal pocket, forming a barrier against bacterial plaque to protect host tissues from destruction.
Area of Science:
- Oral biology
- Immunology
- Histology
Background:
- Polymorphonuclear neutrophils (PMNs) are vital for host defense against oral pathogens.
- Periodontal disease involves inflammation and tissue destruction initiated by microbial plaque.
Purpose of the Study:
- To histologically observe polymorphonuclear neutrophil (PMN) emigration from gingival vessels to the periodontal pocket.
- To examine PMN behavior during gingivitis and ligature-induced periodontitis in cynomolgus monkeys.
Main Methods:
- Histological and electron microscopic observation of gingival tissues from cynomolgus monkeys.
- Induction of gingivitis and early periodontitis using silk ligatures around posterior teeth.
- Analysis of PMN morphology and location in gingival vessels, connective tissue, epithelium, and periodontal pockets.
Main Results:
- PMNs exhibited no morphological differences between gingivitis and periodontitis.
- Endothelial cells actively participated in PMN emigration.
- PMNs were observed within connective tissue, epithelium, and surrounding plaque in the periodontal pocket.
- PMNs near plaque contained bacteria-laden phagolysosomes and showed degeneration within deeper plaque layers.
Conclusions:
- PMN emigration and interaction with bacterial plaque are key components of the host defense in periodontitis.
- The PMN's role in forming a defensive boundary may prevent irreversible host tissue destruction.
- Defects in PMN function are linked to severe, rapidly progressive periodontitis.