FROM JOURNAL OF INVESTIGATIVE DERMATOLOGY

Nitric oxide–releasing nanoparticles prevent Propionibacterium acnes–induced inflammation by clearing the organism and inhibiting microbial stimulation of the innate immune response, new data suggest.

The researchers investigated whether a nitric oxide nanoparticulate system (NO-np), which allowed for the generation and release of NO over time, inhibited bacterial growth in P. acnes strains, and inhibited inflammatory cytokine production from a P. acnes–challenged human keratinocyte cell line and peripheral blood mononuclear cells (PBMCs). The study followed the recent highlighting of P. acnes’ induction of IL-1 cytokines through the NLRP3 inflammasome “as a dominant etiological factor for acne vulgaris,” according to Min Qin, Ph.D., of the University of California, Los Angeles, and his colleagues.

“To demonstrate the bactericidal activity against P. acnes, bacteria were incubated with varying doses of NO-np” for 4 hours, the researchers noted. NO-np was “effective at significantly killing P. acnes, resulting in only 8.9% and 4.6% survival” for two concentrations of NO-np.

While P. acnes were “highly sensitive to all concentrations of NO-np tested,” no cytotoxicities were found in a human keratinocyte, monocyte, and embryonic fish studied.

“We demonstrated that the NO-nps effectively decreased P. acnes viability and inhibited [interleukin]-1B, TNF-alpha, IL-8, and IL-6 secretion from [human monocytes] and IL-8 and IL-6 from keratinocytes, while neither having in vitro nor in vivo cytotoxicity,” according to the researchers. “While NO-np was found to impact components of the NLRP3 inflammasome pathway, its anti-inflammatory effects were not specific to NLRP3, and NLRP3 knockout did not impair NO-np’s anti-inflammatory properties.”

Read the full study in the Journal of Investigative Dermatology ( doi: 10.1038/jid.2015.277 ).

klennon@frontlinemedcom.com

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