Safety and Preliminary Efficacy of a Novel Host-Modulatory Therapy for Reducing Gingival Inflammation

Abstract

Background: Periodontal disease is among the sixth most common inflammatory diseases worldwide with high risk to promote complications from other inflammatory diseases including diabetes, cardiovascular disease and Alzheimer's Disease. Failure of active resolution of inflammation pathways is implicated in pathogenesis of periodontal diseases, including gingivitis. Lipoxin A4 (LXA4), a member of the specialized pro-resolving lipid mediators (SPMs) that drive resolution of inflammation via GPC-receptor mediated pathways, offered therapeutic advantages in preclinical models of periodontitis.

Methods: We conducted a randomized, placebo-controlled, parallel-group Phase 1 clinical trial to determine the safety and preliminary efficacy of an LXA4 analog in patients with gingival inflammation. One hundred twenty-seven (127) individuals were randomized to daily use of an oral rinse containing a LXA4 mimetic, methyl ester-benzo-lipoxin A4 (BLXA4), placebo rinse or a no-rinse control group for 28 days. Treatment emergent adverse events (TEAEs) were assessed for safety, the primary outcome. Secondary outcomes included the change in the level of gingival inflammation and periodontal pocket depth (PD). Serum SPMs were monitored using targeted lipid mediator lipidomics to assess potential systemic impact of BLXA4.

Results: The frequency of TEAEs was similar in BLXA4 and placebo-treated groups with no study-related SAEs. Once-daily rinsing with BLXA4 for 28-days resulted in a greater decrease in gingival inflammation compared to placebo rinse and no-rinse control groups (mean change: 0.26 GI unit vs 0.21 and 0.17, respectively). PD reduction was also greater with BLXA4 oral rinse compared to placebo and no-rinse groups (mean reduction: 1.23 mm vs. 0.71 mm and 0.46 mm, respectively). Topical application of BLXA4 increased serum levels of SPMs.

Conclusion: Treatment with BLXA4 reduces local inflammation, and increases abundance of pro-resolution molecules systemically, which may dampen inflammation that can mediate progression and course of inflammatory diseases beyond periodontitis.

Clinical trial registration: ClinicalTrials.gov, identifier (NCT02342691).

Keywords: gingivitis; host modulation; inflammation; lipid mediators; periodontal inflammation; resolution.

Conflict of interest statement

HH and TD are inventors on several granted and pending licensed and unlicensed patents awarded to the Forsyth Institute that are subject to consulting fees and royalty payments. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2021 Hasturk, Schulte, Martins, Sherzai, Floros, Cugini, Chiu, Hardt and Van Dyke.

Figures

Figure 1

CONSORT diagram. CONSORT subject flow diagram shows the number of subjects screened, enrolled/randomized, and included in the primary safety and secondary efficacy analyses. Out of 579 patients screened, 127 individuals were found eligible, agreed to participate, and enrolled in the study. Fifty participants were randomized to BLXA4 rinse, 50 to placebo rinse and 27 participants to no rinse control group. The primary endpoint safety analysis included all subjects treated with at least one dose of BLXA4 or placebo or those who completed at least one follow up visit after baseline. The secondary endpoint efficacy analysis included those subjects who completed at least one follow up visit (starting at Day 14) for efficacy measures (PD, CAL, BOP, PI). Two subjects dropped out before the necessary Day 14 visit completion, thus replaced per protocol. In BLXA4 group, 3 subjects used unallocated rinse up to 3, 4 and 7 days respectively, thus excluded from efficacy analysis. 1 subject in placebo and 1 subject in no-rinse groups did not complete Day 28 visit (lost-to-follow up and withdrew consent, respectively) and excluded from efficacy analysis for that time point.

Figure 2

Change in gingival index: Primary efficacy endpoint. The key clinical endpoint associated with gingival inflammation was measured using the Modified Gingival Index (MGI) scored 0-4 (healthy-localized mild, generalized mild, moderate and severe). Change from baseline at Day 14 and Day 28 was compared between groups. The BLXA4 group demonstrated greater reduction in gingival inflammation compared to placebo and no rinse groups. *Significant difference compared to placebo rinse (p<0.05); †Significant difference compared to placebo rinse and no-rinse (p<0.05); ^Significant difference compared to no-rinse (p<0.05) by repeated measures mixed models analyses. N=123 (BLXA4: 47, Placebo: 49, No rinse: 27 subjects).

Figure 3

Change in bleeding on probing: Secondary efficacy endpoint. Another key clinical endpoint associated with gingival inflammation, bleeding on probing, was measured using a dichotomous measure, as 1=bleeding 0=no bleeding within 15 minutes following probing the site. Change from baseline at Day 14 and Day 28 was compared between groups. The BLXA4 group demonstrated greater reduction in gingival inflammation compared to placebo group at both Day 14 and Day 28 (*p<0.0001; *p=0.0053, respectively); ANOVA for repeated measures followed by Tukey-Kramer test. N=123 (BLXA4: 47, Placebo: 49, No rinse: 27 subjects).

Figure 4

Change in probing depth: Secondary efficacy endpoint. A post-hoc analysis was conducted in a subgroup of subjects exhibiting periodontal disease with pocket depths ≥ 6 mm at baseline. There were 5 subjects in the BLXA4 group, 7 subjects in the placebo group and 5 subjects in the no rinse group. (BLXA4 vs. placebo, p=0.346; BLXA4 vs. no rinse, p=0.199) and (Placebo vs. no rinse p=0.639) by ANCOVA analysis. Note that all subjects had gingivitis with only a limited number of subjects exhibiting periodontal disease.

Figure 5

Overview of pathways of targeted eicosanoids and specialized pro-resolving mediators and resolution of gingival inflammation. Each are derived from three PUFA namely AA, EPA, and DHA with known biological functions of the pro-inflammatory mediators involved in the initiation of inflammation and of those involved in the resolution of inflammation are included. Mediators whose serum levels increased during inflammation (orange arrow and pink boxes) and during resolution of inflammation (blue arrow) following BLXA4 treatment on Day 28 are shown in blue shaded boxes, respectively.

Figure 6

Impact of local BLXA4 treatment on the systemic inflammatory response. Quantitation and recovery of LMs in serum at baseline and at the end of the treatment on Day 28 were determined using the deuterium labeled internal standards (d8-5-HETE, d5-RvD2, d5-LXA4, d4-LTB4, d4-PGE2; d5-MaR2; 500 pg/μL), and a LM-SPM profile was constructed for each sample. Principal component analysis (PCA) was carried out to classify the observations (change in the BLXA4 and placebo groups) on the basis of lipid mediator levels. (A) 3D score plot of SPMs in serum at Day 28. Lipidomics profiles clearly separated the subjects treated with BLXA4 from placebo. (B) 3D loading plot of SPMs in serum at Day 28. Local treatment with BLXA4 significantly increased the abundance of SPMs in serum and distinctly separated the BLXA4-treated group from placebo group in the composition of lipid mediators indicating a shift in systemic inflammatory response toward resolution correlating with clinical findings.

Figure 7

Changes in serum lipid mediator profiles by topical BLXA4-ME treatment. (A) Sum of pro-resolving mediators (n-3 DHA-derived RvD1-6, PD1, MaR1, MaR2, n-3 EPA-derived RvE1, and AA-derived LXA4, LXB4). (B) Sum of proinflammatory eicosanoids (AA-derived LTB4, PGE2 and PGD2). Results are means ± 95% confidence interval for each subject. (C) Log10 ratio of pro-resolving mediators (SPMs) to proinflammatory eicosanoids, PGD2, PGE2 and LTB4 (Resolution Index). The ratio of pro-resolving lipid mediators to proinflammatory eicosanoids at Day 28 was calculated to determine the resolution index after treatment with BLXA4. Results are shown as individual results for each patient, horizontal bars depicting median values. Statistical analysis was conducted using one-way ANOVA followed by Tukey post-hoc test. † p<0.05 compared to no rinse; * p<0.05 compared to placebo; N=47 BLXA4-treated subjects, N=48 placebo and N=26 no rinse.