Nupharidine enhances Aggregatibacter actinomycetemcomitans clearance by priming neutrophils and augmenting their effector functions

Abstract

Objectives Nupharidine (6,6′‐Dihydroxythiobinupharidine), purified from the aquatic plant Nuphar lutea leaves (Water lily) prompts antimicrobial activity of immune cells. The aim of the study was to test the effect of Nupharidine on neutrophil function against Aggregatibacter actinomycetemcomitans, JP2 clone (Aa‐JP2). Methods Neutrophils derived from the human cell line HL60 and human peripheral blood derived from aggressive periodontitis and periodontally healthy subjects were incubated with Nupharidine or vehicle and inoculated with JP2. Bacterial survival was tested using viable counts on blood agar (CFU's). Neutrophils’ necrosis/apoptosis, reactive oxygen species (ROS) production, phagocytosis and neutrophil extracellular traps (NET) production following infection were tested, as well as markers of neutrophil priming. Results Nupharidine had no direct bactericidal effect on JP2, but it enhanced Aa‐JP2 clearance by neutrophils. Nupharidine enhanced neutrophil phagocytosis, ROS production and NET formation during JP2 infection. Furthermore, Nupharidine enhanced the expression of certain markers of neutrophils priming, specifically iCAM1, DECTIN‐2 and intracellular IL‐1β. Conclusion Nupharidine was shown to promote neutrophil effector bactericidal functions, boosting Aa‐JP2 clearance. The results point to the potential of Nupharidine as an adjunctive agent in the treatment of Aa‐JP2 periodontitis, but this should be tested initially using pre‐clinical and clinical studies.

Neutrophil Extracellular Traps in Periodontitis

“…Treatment with Nupharidine, an agent purified from the plant Nuphar lutea, has been shown to increase NET extrusions by neutrophil-like cells by 106%. However, the authors claim that whether the increase in NET extrusion by this compound has a detrimental or protective effect on the periodontal tissues requires further in vivo research [64]. Therefore, NETs can be considered as potential therapeutic targets for periodontitis as well as for other diseases of autoimmune origin.…”

Mast cells exhibit intracellular microbicidal activity against Aggregatibacter actinomycetemcomitans

“…The in vitro microbicidal activity of other phagocytes against A actinomycetemcomitans has also been demonstrated. A recent study using human neutrophils revealed a faster microbicidal action of these cells against A actinomycetemcomitans via intracellular reactive oxygen species, with a challenge time of 1 hour and MOI 10 32 . The ability of MCs to kill E coli was also evidenced by us and other authors 27,28 .…”

Nuphar lutea Extracts Exhibit Anti-Viral Activity against the Measles Virus

“…We have preliminary, unpublished data, showing that both the extract and the purified molecule inhibit cathespsins, which are cysteine proteases, likely by forming a disulfide bond at the enzyme's active site. Lastly, we recently published that the purified molecule primes neutrophils against bacteria present in gum inflammation, enhances phagocytosis, ROS production, and NET formation [30].…”