Squalene and its uses

Squalene is an organic compound.It is a triterpenoid with the molecular formula C30H50.It is a colorless oil, but impure samples are yellow.It was originally extracted from shark liver oil (hence the name, since dogfish is a genus of sharks).An estimated 12 percent of the squalene in the human body is found in sebum.Squalene has topical skin lubricating and protective effects.Most plants, fungi and animals produce squalene as a biochemical precursor for the biosynthesis of sterols, including cholesterol and steroid hormones in humans.It is also an intermediate in terpenoid biosynthesis in many bacteria.Squalene is an important component of some vaccine adjuvants: Novartis and GlaxoSmithKline’s adjuvants are called MF59 and AS03 respectively.

Uses

As an adjuvant in vaccines: 

Adjuvants are substances used with vaccines to stimulate the immune system and enhance the response to the vaccine.Squalene itself is not an adjuvant,but it has been used in combination with surfactants in some adjuvant formulations. The adjuvant using squalene is Seqirus' proprietary MF59,which is added to flu vaccines to help stimulate the body's immune response by generating CD4 memory cells.It is the first oil-in-water influenza vaccine adjuvant commercialized with a seasonal influenza virus vaccine.It was developed in the 1990s by researchers at Ciba-Geigy and Chiron; both companies were subsequently acquired by Novartis.Novartis was later acquired by CSL Bering and created Seqirus.It comes in the form of an emulsion and when added to make the vaccine more immunogenic.However, the mechanism of action remains unknown.MF59 is able to turn on many genes that partially overlap with those activated by other adjuvants.How these changes are triggered is unclear; to date, no receptors responsive to MF59 have been identified.One possibility is that MF59 affects cellular behavior by altering lipid metabolism, that is, by inducing the accumulation of neutral lipids in target cells.Beginning with the 2016-2017 flu season, an influenza vaccine called FLUAD, which uses MF59 as an adjuvant, has been approved for use in the United States by people 65 and older.

A 2009 meta-analysis evaluated data from 64 clinical trials of influenza vaccines using the squalene-adjuvanted MF59 and compared them to vaccines without the adjuvant.The analysis reported that adjuvanted vaccines were associated with a slightly lower risk of chronic disease,but that neither vaccine modified the incidence of autoimmune disease; the authors concluded that their data "support a favorable safety profile associated with the MF59 adjuvanted influenza vaccine and suggest possible clinical benefit over vaccines that do not contain MF59".