To study the changes in levels of interleukin (IL)-6, IL-10, tumor necrosis factor-alpha (TNF-α), and alkaline phosphatase (ALP) in the gingival crevicular fluid (GCF) of patients with severe chronic periodontitis before and after nonsurgical periodontal therapy and to explore the relationship among the levels of these four biomarkers in GCF, their periodontal status and their clinical significance to evaluate the effect of nonsurgical periodontal therapy and periodontitis activity.

In total, 30 patients with severe chronic periodontitis were enrolled in a 1-year longitudinal pilot study (Chinese Clinical Trial Registry: ChiCTR-OCH- 13004679). At baseline and 1, 3, 6, and 12 months after nonsurgical therapy, the periodontal clinical indicators plaque index (PLI), probing depth (PD), clinical attachment loss (CAL), sulcus bleeding index (SBI) were recorded. Filter paper strips were used to collect two deep-pocket (probing depth ≥ 6 mm) and two shallow-pocket (probing depth ≤ 4 mm) periodontal sites for each patient and weighed. The levels of interleukin IL-6, IL-10, TNF-α, and ALP in GCF were assessed using enzyme-linked immunosorbent assay. Meanwhile, 30 healthy sites of 15 subjects with healthy periodontium were used as the baseline controls for patients with severe chronic periodontitis.

At the baseline, the TNF-α, ALP and IL-6 levels in GCF of the disease sites of patients with periodontitis were significantly higher than those in healthy periodontal sites of the control group (P < 0.001), and the levels of IL-10 were significantly lower than those in the control group (P < 0.001). In patients with severe chronic periodontitis, the levels of TNF-α, ALP and IL-6 in GCF at deep-pocket sites were significantly higher than those at shallow-pocket sites (P <0.001), and the IL-10 levels were significantly lower than those at shallow-pocket sites (P < 0.001). 1, 3, 6, and 12 months after nonsurgical treatment, the levels of TNF-α and ALP in GCF at the shallow- and deep-pocket sites in patients with chronic periodontitis significantly decreased, the level of IL-10 significantly increased (P < 0.005), and the level of IL-6 in GCF at the deep-pocket sites significantly decreased (P < 0.005). However, there was no significant difference in IL-6 level at shallow-pocket sites (P > 0.05). 1, 3, 6, and 12 months after nonsurgical treatment, the periodontal clinical indicators were improved compared with the baseline. In addition, there was a significant correlation between the levels of these four biomarkers and the periodontal clinical parameters (P < 0.05). During the two follow-up visits after nonsurgical periodontal therapy, the sites with more than 2-mm increase in attachment loss had significant differences in the levels of the four biomarkers in the GCF compared with the previous visit time (P < 0.005).

The detection of the levels of these four biomarkers in GCF has strong clinical significance for assessing the severity of periodontitis and the efficacy of nonsurgical periodontal therapy. Increased levels of TNF-α, ALP, and IL-6 and decreased IL-10 levels in GCF may indicate periodontitis progression at this site.

To examine the effect of intracellular vesicles (IVs) and extracellular vesicles (EVs) that originated from periodontal ligament stem cells (PDLSCs) on the osteogenic differentiation of PDLSCs within a lipopolysaccharide (LPS)-simulated inflammatory microenvironment, and to provide new insights for the application of IVs in the repair and regeneration of periodontal tissue in periodontitis.

Ethical approval was obtained from the institution. Human-origin PDLSCs were extracted, and the IVs and EVs from PDLSCs at the 3rd-6th passages were gathered and identified using transmission electron microscopy, nano flow cytometry (Nano FCM) analysis, and Western Blot. The 3rd-6th generations of PDLSCs were categorized into the following groups: Control group, LPS group, LPS + 100 μg/mL EVs group (LPS+EVs group), and LPS + 100 μg/mL IVs group (LPS+IVs group). The effects of the IVs and EVs on the anti-inflammatory and osteogenic differentiation of PDLSCs in an inflammatory microenvironment were assessed by using a Cell Counting Kit-8 (CCK-8), enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), Western Blot, alkaline phosphatase (ALP) staining, and alizarin red staining (ARS).

Under transmission electron microscopy, the IVs and EVs derived from PDLSCs displayed a double-layer membrane structure. NanoFCM analysis revealed that the average diameters of the IVs and EVs were 79.6 nm and 82.1 nm, respectively. Western Blot analysis indicated that the surface proteins CD9, CD63, and CD81 of the IVs and EVs were positively expressed, while calnexin was negatively expressed, indicating that IVs and EVs were successfully obtained. Compared with the Control group, the proliferation of PDLSCs in the LPS group was reduced, while the levels of inflammatory cytokine interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the cell supernatant were increased, the mRNA expressions of osteogenic differentiation-related genes, including osteoblast-related genes runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OCN) of PDLSCs were reduced, the protein expressions of RUNX2 and osteopontin (OPN) were also decreased (P < 0.05); compared with the LPS group, the proliferation of PDLSCs in the LPS+EVs group and LPS+IVs group were significantly increased, while the levels of IL-6, TNF-α were significantly reduced, and the mRNA expressions of RUNX2, ALP, OCN were significantly increased, the protein expressions of RUNX2 and OPN were also significantly increased (P < 0.05). Further, in the inflammatory microenvironment, Compared with EVs, IVs more significantly promote the proliferation of PDLSCs, inhibit TNF-α expression, enhance the expression of RUNX2 mRNA, upregulate the expression of RUNX2 and OPN proteins, increase ALP activity, and promote the formation of mineralized nodules (P < 0.05).

IVs and EVs derived from PDLSCs can boost the proliferation of PDLSCs in an inflammatory microenvironment, inhibit the expression of inflammatory factors, and advance the osteogenic differentiation of PDLSCs. The anti-inflammatory and osteogenic effects of IVs are superior to those of EVs.