Abstract
Oral ulcerations often arise as a side effect from chemo- and radiation therapy. In a previous clinical study, Porphyromonas gingivalis was identified as a positive predictor for oral ulcerations after hematopoetic stem cell transplantation, possibly incriminating P. gingivalis in delayed healing of the ulcerations. Therefore, it was tested whether P. gingivalis and its secreted products could inhibit the migration of oral epithelial cells in an in vitro scratch assay. To compare, the oral bacteria Prevotella nigrescens, Prevotella intermedia, Tannerella forsythia, and Streptococcus mitis were included. A standardized scratch was made in a confluent layer of human oral epithelial cells. The epithelial cells were challenged with bacterial cells and with medium containing secretions of these bacteria. Closure of the scratch was measured after 17 h using a phase contrast microscope. P. gingivalis, P. nigrescens, and secretions of P. gingivalis strongly inhibited cell migration. A challenge with 1000 heat-killed bacteria versus 1 epithelial cell resulted in a relative closure of the scratch of 25% for P. gingivalis and 20% for P. nigrescens. Weaker inhibitory effects were found for the other bacteria. The results confirmed our hypothesis that the oral bacteria may be involved in delayed wound healing.
Highlights
The oral mucosa serves as a physical barrier to protect the underlying tissues from the entry of microorganisms from the oral cavity
In a previous prospective clinical study, we studied the relationship between bacteria that are associated with periodontitis and oral ulcerations in hematopoietic stem cell transplant (HSCT) recipients [10]
The inhibition of oral epithelial cell migration by P. gingivalis is shown in Figures 1(a) and 2
Summary
The oral mucosa serves as a physical barrier to protect the underlying tissues from the entry of microorganisms from the oral cavity. The outer layer of the oral mucosa consists of epithelial cells [1] that are in constant contact with these oral microorganisms. Ulcerations of the oral mucosa often occur as a side effect of chemo- and radiation therapy for cancer treatment [5, 6]. These ulcerations are very painful and cause the patient substantial discomfort. Healing consists of three phases that overlap in time, inflammation, cell proliferation and reepithelialisation, and remodeling of the tissue [7]. In vitro scratch assays are commonly used with the scratched area before and after migration as the main outcome parameter [8]
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