Interaction of dental pulp stem cells with bacterial products modulates the protein expression of Cathepsin B
Creators: name: Obe, Olajide
Publisher: name: University of Iowa
Year: 2026
Subjects: Cathepsin B
Dental Pulp Stem Cells
Lactobacillus rhamnosus
Lipopolysaccharide
Lipoteichoic acid
Streptococcus mutans
public abstract

description: Title: Interaction of Dental Pulp Stem Cells with Bacterial Products modulates the Protein Expression of Cathepsin B.Objective: Endogenous enzymes, such as cysteine cathepsins, have been showed to be the key proteases driving dentin degradation in caries progression. While acid-activation is the currently accepted mechanism for the activation of endogenous proteases from the dentin, odontoblasts-derived enzymes might be released by pulp in response to bacterial infiltration. The aim of this study was to characterize the effect of stimulation of human dental pulp stem cells (DPSC) with bacterial products on the in vitro protein expression of cathepsin B. More specifically, DPSC response to purified bacterial products as well as spent-culture filtrates of Streptococcus mutans (SM) and Lactobacillus rhamnosus (LR) was investigated. The specific hypotheses were: 1. purified molecules of lipopolysaccharide (LPS) and/or lipoteichoic acid (LTA) would modulate the protein expression of cathepsin B by human DPSC; and 2. the spent-culture filtrates from pure colonies of SM and/or LR would modulate the protein expression of cathepsin B by human DPSC.
description: Methods: The first part of the in vitro study addressed the first hypothesis and has three experimental groups: 1) ⍺-MEM (control); 2) ⍺-MEM + LPS; and 3) ⍺-MEM + LTA. The second part addressed the second hypothesis and has three experimental groups: 1) ⍺-MEM + D-MEM (control); 2) ⍺-MEM + D-MEM + SM; and 3) ⍺-MEM + D-MEM + LR. The study was conducted using immortalized human DPSC, LPS from Escherichia coli O111:B4, LTA from Bacillus subtilis, Streptococcus mutans (ATCC 25175), and Lactobacillus rhamnosus (ATCC 53103). Initially, cell viability assays were performed to determine the ideal concentrations and incubation time for DPSC stimulation with the bacterial products. Then, DPSC supernatants and lysates were collected from DPSC following the stimulation of the DPSC with LPS, LTA, SM, or LR filtrates for 24 h. DPSC supernatants and lysates were analyzed for the quantitative detection of total protein and expression of cysteine cathepsin B. Data analysis was performed using Shapiro-Wilk’s test, two-way ANOVA and Tukey HSD post hoc tests (α=0.05).
description: Results: The cell viability results for different concentrations of LTA and LPS revealed that DPSC incubated with 10 µg/mL LPS showed the highest viability amongst the LPS groups, while 2.5 µg/mL LTA showed the highest viability amongst the LTA groups. The cell viability results for the LTA, LPS, SM and LR groups showed an overall decrease in DPSC viability from 24 h to the 48 h of stimulation, with statistically significant difference for LPS (p = 0.037) and LTA (p &lt; 0.001) groups. The cell viability results for DPSC stimulated with bacterial filtrates showed an increase in the viability of the DPSC from the 24 h to the 48 h incubation, however, there was no statistically significant differences among the groups (p &gt; 0.05). The DPSC stimulation with LTA resulted in the highest total protein for the supernatants, but the lowest for lysates when compared to LPS and control. However, the ANOVA tests revealed no significant difference in the total protein concentration among the groups for the supernatants and lysates for both LPS, LTA, and culture filtrates (p &gt; 0.05). The results for cathepsin B expression for the DPSC supernatants after 24 h of stimulation with purified products and culture filtrates showed a significant reduction in the cathepsin B expression by the LTA group (p = 0.036) and the LR (p = 0.008) group compared to their controls.
description: Conclusion: The purified molecules of LTA and spent-culture filtrates from pure colonies of Lactobacillus rhamnosus modulated the protein expression of cathepsin B by human DPSC and resulted in a significant decrease in the levels of this enzyme.