Enhancement of innate immunity in gingival epithelial cells by vitamin D and HDAC inhibitors

Erika L Figgins; Payal Arora; Denny Gao; Emily Porcelli; Rabab Ahmed; Carlo Amorin Daep; Garrett Keele; Lisa K Ryan; Gill Diamond

doi:10.3389/froh.2024.1378566

Enhancement of innate immunity in gingival epithelial cells by vitamin D and HDAC inhibitors

Front Oral Health. 2024 Mar 14:5:1378566. doi: 10.3389/froh.2024.1378566. eCollection 2024.

Authors

Erika L Figgins^{1

2}, Payal Arora³, Denny Gao², Emily Porcelli¹, Rabab Ahmed³, Carlo Amorin Daep³, Garrett Keele², Lisa K Ryan^{2

4

5}, Gill Diamond^{1

2

5}

Affiliations

¹ Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, United States.
² Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, United States.
³ Global Technology Center, Colgate Palmolive Company, Piscataway, NJ, United States.
⁴ Division of Infectious Disease and Global Medicine, Department of Medicine, University of Florida College of Medicine, Gainesville, FL, United States.
⁵ Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, KY, United States.

Abstract

Introduction: The human host defense peptide LL-37 is a component of the innate immune defense mechanisms of the oral cavity against colonization by microbes associated with periodontal disease. We have previously shown that the active form of vitamin D, 1,25(OH)₂D₃, can induce the expression of LL-37 in gingival epithelial cells (GEC), and prevent the invasion and growth of periopathogenic bacteria in these cells. Further, experimental vitamin D deficiency resulted in increased gingival inflammation and alveolar bone loss. Epidemiological studies have shown associations between vitamin D deficiency and periodontal disease in humans, suggesting application of vitamin D could be a useful therapeutic approach. Further, since we have shown the local activation of vitamin D by enzymes expressed in the GEC, we hypothesized that we could observe this enhancement with the stable, and inexpensive inactive form of vitamin D, which could be further increased with epigenetic regulators.

Methods: We treated 3-dimensional primary cultures of GEC topically with the inactive form of vitamin D, in the presence and absence of selected histone deacetylase (HDAC) inhibitors. LL-37 mRNA levels were quantified by quantitative RT-PCR, and inhibition of invasion of bacteria was measured by fluorescence microscopy.

Results: Vitamin D treatment led to an induction of LL-37 mRNA levels, as well as an inhibition of pro-inflammatory cytokine secretion. This effect was further enhanced by HDAC inhibitors, most strongly when the HDAC inhibitor, phenyl butyrate (PBA) was combined with Vitamin D₃. This was observed both in solution and in a prototype gel formulation using sodium butyrate. Finally, this combination treatment led to an increase in the antimicrobial activity against infection by Porphyromonas gingivalis and Filifactor alocis, bacteria associated with periodontal lesions, as well as herpes simplex virus, which has also been shown to be associated with periodontal lesions.

Conclusions: Our results demonstrate that a combination of inactive vitamin D and sodium butyrate could be developed as a safe treatment for periodontal disease.

Keywords: anti-inflammatory; antimicrobial peptide; antiviral; periodontal; vitamin D.

Abstract

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