The neutrophil subset defined by CD177 expression is preferentially recruited to gingival crevicular fluid in periodontitis

Abstract

In recent years, the concept of distinct subpopulations of human neutrophils has attracted much attention. One bona fide subset marker, exclusively expressed by a proportion of circulating neutrophils in a given individual, and therefore dividing neutrophils in two distinct subpopulations, is the glycoprotein CD177. CD177 is expressed on the plasma and granule membranes of 0-100% of circulating neutrophils depending on the donor. Several in vitro studies have linked CD177 to neutrophil transmigration, yet very few have looked at the role of CD177 for tissue recruitment in vivo. We investigate whether the CD177 + and CD177neutrophil subsets differ in their propensity to migrate to both aseptic-and microbe-triggered inflamed human tissues. Microbe-triggered neutrophil migration was evaluated in samples of gingival crevicular fluid (GCF) from patients with periodontitis, whereas neutrophil migration to aseptic inflammation was evaluated in synovial fluid from patients with inflammatory arthritis, as well as in exudate from experimental skin chambers applied on healthy donors. We found that the proportion of CD177 + neutrophils was significantly higher in GCF from patients with periodontitis, as compared to blood from the same individuals. Such accumulation of CD177 + neutrophils was not seen in the two models of aseptic inflammation. Moreover, the proportion of CD177 + neutrophils in circulation was significantly higher in the periodontitis patient group, as compared to healthy donors. Our data indicate that the CD177 + neutrophil subset is preferentially recruited to the gingival crevice of periodontitis patients, and may imply that this subtype is of particular importance for situations of microbedriven inflammation.

Letter to the Editor

“…In our own study on CD177 + neutrophil migration in highly acute, mostly bacterial peritonitis, we did not observe a change in CD177 MFI of the CD177‐negative neutrophil subpopulation 6 . Possibly, formation of membrane vesicles that mediate receptor transfer is favored in more chronic inflammatory processes investigated in the present publication and earlier 1,2 …”

“…To the Editor, With great interest we have read the recent article by Dahlstrand Rudin and colleagues addressing CD177 + and CD177 − neutrophilic granulocyte subset accumulation in human periodontitis. 1 We would like to discuss a possible additional explanation of these findings beyond differential recruitment. The flow cytometric histogram in figure 2E appears to depict an upward shift in the CD177mean fluorescence intensity (MFI) of the CD177 negative population.…”

“…6 Possibly, formation of membrane vesicles that mediate receptor transfer is favored in more chronic inflammatory processes investigated in the present publication and earlier. 1,2 Sincerely,…”

“…With great interest we have read the recent article by Dahlstrand Rudin and colleagues addressing CD177 + and CD177 − neutrophilic granulocyte subset accumulation in human periodontitis 1 …”

Reply to Julia Volkmann and Sibylle von Vietinghoff

“…2 This could clearly be seen in samples from skin chambers and also in vitro after TNF-priming. 1 In our GCF samples, we noted that not only was the MFI of the CD177 + population increased, but the entire histograms were often right-shifted with increased MFI of both the CD177 + and CD177populations (Fig. 1A).…”