Human β-defensins are correlated with the immune infiltration and regulated by vitamin D in periodontitis.

OBJECTIVE

Exploring the correlation between human β-defensins (HBDs) and immune infiltration in periodontitis, and whether it is regulated by vitamin D .

BACKGROUND

The human body produces essential antimicrobial peptides called HBDs, which are associated with periodontitis. There is a strong link between periodontal tissue destruction and the immune cell infiltration. Moreover, vitamin D has been reported to regulate the expression of immune cell chemokines. However, the relationship between vitamin D , HBDs, and immune infiltration in periodontitis remains to be investigated.

METHODS

The Gene Expression Omnibus database was accessed to obtain transcriptomic information of gingival samples taken from periodontitis patients. The expression value of HBD-2 and HBD-3 was calculated. Additionally, using the online program ImmuCellAl, 10 immune cells were scored for immune infiltration in the high-HBDs-expression group and the low-HBDs-expression group, separately. After that, transcriptome sequencing was done based on human gingival fibroblasts that had received vitamin D treatment. Furthermore, hGFs were treated by vitamin D , tumor necrosis factor-α (TNF-α), and Porphyromonas gingivalis lipopolysaccharide (Pg-LPS). The expressions of HBD-2, HBD-3, interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) were detected. To seek the potential mechanism, CYP27A1 siRNA was employed to reduce the expression of CYP27A1, and nuclear factor-gene binding protein 65 (NF-κB p65) was examined.

RESULTS

In GSE10334, the expressions of HBD-2 and HBD-3 were down-regulated in periodontitis group. Meanwhile, monocyte, macrophage, and CD4_T cell were less infiltrated in low-HBD-2-expression group, while less Gamma-delta T-cell infiltration was found in low-HBD-3-expression group. Transcriptome sequencing found that 21 genes were significantly expressed, of which the function was enriched in response to bacterial origin and TNF signal pathway. Vitamin D could significantly up-regulate the expression of HBD-2 and HBD-3, which could be controlled by knocking down CYP27A1 mRNA expression. With prolonged vitamin D stimulation, the expression of HBD-2 and HBD-3 increased. TNF-α/Pg-LPS could significantly increase the expression of HBD-2, HBD-3, IL-8, MCP-1, and p65, all of which were reduced by vitamin D .

CONCLUSION

HBDs are correlated with immune infiltration in periodontitis. Vitamin D inhibits the expression of HBDs and chemokines induced by TNF-α/Pg-LPS, possibly through NF-κB pathway, in human gingival fibroblasts.