CONFERENCE REPORT

The resolution of inflammation: Is thereanything nutrients can do for it?

A. J. SinclairDeakin University, Melbourne, Australia

The International Union of NutritionSocieties (IUNS) 20th InternationalCongress of Nutrition (ICN), Granada,Spain, 15–20 September 2013

During the 2013 IUNS ICN conference, there were fourdaily plenary lectures, the first of which by ProfessorCharles Serhan covered the topic of diet and inflamma-tion. Dr Serhan, Professor of Oral Biology at Harvard,who has a strong interest in periodontal disease and theresolution of inflammation gave a presentation entitled‘The resolution of inflammation. Is there anything nutri-ents can do for it?’ In this talk he discussed how nutri-tion may have a role in reducing inflammation.

Inflammation is an innate response that occurs inresponse to injury or invading organisms. This is usuallya temporary response, initiated as a protective mecha-nism; however, in some cases, the inflammatory responsepersists and becomes detrimental. This can lead to tissuedamage, as seen in a number of inflammatory diseases,including arthritis (Kohli & Levy 2009). Dr Serhanexplained how the process of inflammation can be linkedto nutrition through the involvement of metabolites ofcell membrane-derived polyunsaturated fatty acids(PUFAs) of both the omega 6 (n-6) and omega 3 (n-3)series; namely arachidonic acid (n-6 fatty acid) andthe n-3 fatty acids, eicosapentaenoic acid (EPA),docosapentaenoic acid (DPA) and docosahexaenoic acid(DHA). These fatty acids are the precursors to a numberof local mediators including lipoxins, resolvins,protectins and maresins, all of which are importantcompounds involved in the resolution of inflammation.

During the process of inflammation, fatty acids arecleaved from the cell membrane phospholipids byphospholipases (enzymes that break down phospholipidsinto fatty acids and other lipophilic substances) followingthe cell receiving a stimulus. The liberated PUFAs arethen capable of acting as substrates for cyclooxygenase(the enzymes responsible for the formation ofprostanoids, including prostaglandins, prostacyclin andthromboxane) or lipoxygenase enzymes (the enzymesresponsible for the dioxygenation of PUFAs) located inthe cell. These enzymes convert each of the differentPUFAs into specific products with either pro-inflammatory actions (such as leukotriene B4 and pros-taglandin E2 from arachidonic acid) or anti-inflammatory actions (such as prostaglandin E3 fromEPA). These metabolites are broadly referred to as pros-taglandins, leukotrienes and related eicosanoids [20carbon fatty acid compounds typically containinghydroxyl (-OH) groups].

Moving on to talk specifically about resolvins, DrSerhan described the chemistry of two categories ofresolvins: those derived from EPA (E-series resolvins) andthose from DPA and DHA (D-series resolvins). Heexplained how DHA also serves as a precursor toother anti-inflammatory compounds, specifically theprotectins and maresins. These bioactive compounds arepotent mediators produced during the resolution phaseof acute inflammation. They were first identified in self-resolving inflammatory exudates and are now recognisedfor their important role(s) in modulating leucocyte (whiteblood cell) responses in the resolution of inflammation.

Dr Serhan then described the temporal processesinvolved in inflammation, including oedema (fluid reten-tion) followed by white blood cell (polymorphonuclearcell) infiltration and then infiltration of other white bloodcells (monocytes/macrophages) (defence mechanisms),and discussed how the E-series resolvins produced bymacrophages stop polymorphonuclear cell infiltrationand coordinate the resolution phase of the inflammation.

Correspondence: Professor Andrew Sinclair, Professor of NutritionScience, Deakin University, Waurn Ponds, Melbourne, Victoria3217, Australia.E-mail: andrew.sinclair@deakin.edu.au

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DOI: 10.1111/nbu.12080

© 2014 British Nutrition Foundation Nutrition Bulletin, 39, 141–142 141

Resolvins are active in the 100 ng range compared withthe drugs dexamethasone and aspirin, in the range of10 μg and 1 mg range, respectively (1 μg = 1000 ng;1 μg = 0.001 mg), suggesting that resolution of inflam-mation may be an active process rather than a passiveone. Further information on the resolution process andresolvin involvement has been provided in a recentreview (Dalli et al. 2013).

Serhan then described recent data that revealed thatpro- and anti-inflammatory lipid mediators are presentin high quantities in human milk, and how this may beindicative of their involvement in neonatal immunity(Weiss et al. 2013). The authors thought that the pres-ence of these anti-inflammatory lipid mediators inhuman milk may indicate a role for them in neonatalimmunity. The final matter of interest discussed in DrSerhan’s presentation was the discovery that infectionmay differentially regulate pro-resolving mediators tohelp restrict the spread of infection, thus lowering anti-biotic requirements for bacterial clearance. This is basedon findings from a recent study using leukocytes frommice and isolated human cells (Chiang et al. 2012). Theauthors suggested that these findings might lead to newopportunities to address antibiotic resistance by lower-ing antibiotic use through the targeting of the host’spro-resolving mediators.

Overall, Dr Serhan provided a thoroughly interest-ing presentation that was densely packed with detailsof the many interesting properties of these novel lipidmediators, which are derived from long-chain n-3 fattyacids.

Conflict of interest

The author has no conflict of interest to declare.

References

Chiang N, Fredman G, Backhed F et al. (2012) Infection regulatespro-resolving mediators that lower antibiotic requirements.Nature 484: 524–8.

Dalli J, Winkler JW, Colas RA et al. (2013) Resolvin D3 andaspirin-triggered resolving D3 are potent immunoresolvents.Chemistry and Biology 20: 188–201.

Kohli P & Levy BD (2009) Themed section: mediators and recep-tors in the resolution of inflammation, resolvins and protectins:mediating solutions to inflammation. British Journal of Pharma-cology 158: 960–71.

Weiss GA, Troxler H, Klinke G et al. (2013) High levels of anti-inflammatory and pro-resolving lipid mediators lipoxins andresolvins and declining docosahexaenoic acid levels in humanmilk during the first month of lactation. Lipids in Health andDisease 12: 89.

142 A. J. Sinclair

© 2014 British Nutrition Foundation Nutrition Bulletin, 39, 141–142