Levels of low-molecular-weight hyaluronan in periodontitis-treated patients and its immunostimulatory effects on CD4+ T lymphocytes

Clin Oral Investig. 2021 Aug;25(8):4987-5000. doi: 10.1007/s00784-021-03808-9. Epub 2021 Feb 5.

Abstract

Objectives: During periodontitis, chronic inflammation triggers soft tissue breakdown, and hyaluronan is degraded into fragments of low molecular weight (LMW-HA). This investigation aimed to elucidate whether LMW-HA fragments with immunogenic potential on T lymphocytes remain in periodontal tissues after periodontal treatment.

Materials and methods: GCF samples were obtained from 15 periodontitis-affected patients and the LMW-HA, RANKL, and OPG levels were analyzed before and after 6 months of periodontal treatment by ELISA. Eight healthy individuals were analyzed as controls. Besides, human T lymphocytes were purified, exposed to infected dendritic cells, and pulsed with LMW-HA. Non-treated T lymphocytes were used as control. The expression levels of the transcription factors and cytokines that determine the Th1, Th17, and Th22 lymphocyte differentiation and function were analyzed by RT-qPCR. Similarly, the expression levels of RANKL and CD44 were analyzed.

Results: In the GCF samples of periodontitis-affected patients, higher levels of LMW-HA were detected when compared with those of healthy individuals (52.1 ± 15.4 vs. 21.4 ± 12.2, p < 0.001), and these increased levels did not decrease after periodontal therapy (52.1 ± 15.4 vs. 45.7 ± 15.9, p = 0.158). Similarly, the RANKL levels and RANKL/OPG ratios did not change after periodontal therapy. Furthermore, in human T lymphocytes, LMW-HA induced higher expression levels of the Th1, Th17, and Th22-related transcription factors and cytokines, as well as CD44 and RANKL, as compared with non-treated cells.

Conclusions: In some patients, increased levels of LMW-HA persist in periodontal tissues after conventional periodontal therapy, and these remaining LMW-HA fragments with immunostimulatory potential could induce the polarization of a pathologic Th1/Th17/Th22-pattern of immune response on T lymphocytes.

Clinical relevance: The persistence of increased levels of LMW-HA in periodontal tissues after periodontal therapy could favor the recurrence of the disease and further breakdown of periodontal supporting tissues.

Keywords: CD44; Cytokines; Hyaluronic acid; LMW-HA; RANKL; T lymphocytes.

MeSH terms

  • Cytokines
  • Humans
  • Hyaluronic Acid*
  • Molecular Weight
  • Periodontitis* / drug therapy
  • RANK Ligand
  • Th17 Cells

Substances

  • Cytokines
  • RANK Ligand
  • Hyaluronic Acid