Siglec-F–expressing neutrophils are essential for creating a profibrotic microenvironment in renal fibrosis
Seungwon Ryu, … , Seung Hee Yang, Hye Young Kim
Seungwon Ryu, … , Seung Hee Yang, Hye Young Kim
Published April 28, 2022
Citation Information: J Clin Invest. 2022;132(12):e156876. https://doi.org/10.1172/JCI156876.
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Research Article Immunology Nephrology

Siglec-F–expressing neutrophils are essential for creating a profibrotic microenvironment in renal fibrosis

Abstract

The roles of neutrophils in renal inflammation are currently unclear. On examining these cells in the unilateral ureteral obstruction murine model of chronic kidney disease, we found that the injured kidney bore a large and rapidly expanding population of neutrophils that expressed the eosinophil marker Siglec-F. We first verified that these cells were neutrophils. Siglec-F+ neutrophils were recently detected in several studies in other disease contexts. We then showed that a) these cells were derived from conventional neutrophils in the renal vasculature by TGF-β1 and GM-CSF; b) they differed from their parent cells by more frequent hypersegmentation, higher expression of profibrotic inflammatory cytokines, and notably, expression of collagen 1; and c) their depletion reduced collagen deposition and disease progression, but adoptive transfer increased renal fibrosis. These findings have thus unveiled a subtype of neutrophils that participate in renal fibrosis and a potentially new therapeutic target in chronic kidney disease.

Authors

Seungwon Ryu, Jae Woo Shin, Soie Kwon, Jiwon Lee, Yong Chul Kim, Yoe-Sik Bae, Yong-Soo Bae, Dong Ki Kim, Yon Su Kim, Seung Hee Yang, Hye Young Kim

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Figure 5

Siglec-F+ neutrophils produce more profibrotic cytokines than conventional neutrophils and are also collagen-producing cells.

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Siglec-F+ neutrophils produce more profibrotic cytokines than convention...
(A and B) Flow cytometric comparison of conventional neutrophils and Siglec-F+ neutrophils in the UUO-injured kidney at day 7 (n = 10 in each group) in terms of their surface (A) and intracellular (B) levels of inflammatory and homeostatic markers. The box plots depict the minimum and maximum values (whiskers), the upper and lower quartiles, and the median. The length of the box represents the interquartile range. (C and D) Depiction of the experiment (n = 6 in each group) where bone marrow–derived neutrophils were induced to convert into Siglec-F+ neutrophils by priming with TGF-β1 or GM-CSF, after which they were cocultured with NIH 3T3 fibroblasts (C). After the neutrophils were washed out, the fibroblasts were subjected to Western blot analysis for COL1A1 and α-SMA, which are fibroblast activation and differentiation markers (D). (E) Flow cytometric analysis of the intracellular levels of COL1A1 in the CD45+ immune cells and CD45– non-immune cells from sham- and UUO-treated kidneys at day 7. (F and G) Sorted conventional and Siglec-F+ neutrophils from UUO-treated kidneys at day 14 (n = 6 in each group) were subjected to immunofluorescence (F) and RT-qPCR (G) analysis of COL1A1 protein expression. Scale bar: 5 μm. All results are shown as mean ± SEM, and statistical analysis was performed using Student’s t test (A, B, and G) or 1-way ANOVA (D). *P < 0.05; **P < 0.01; ****P < 0.0001.