Transcription factor NFAT5 promotes macrophage survival in rheumatoid arthritis
Susanna Choi, … , Chul-Soo Cho, Wan-Uk Kim
Susanna Choi, … , Chul-Soo Cho, Wan-Uk Kim
Published February 13, 2017
Citation Information: J Clin Invest. 2017;127(3):954-969. https://doi.org/10.1172/JCI87880.
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Research Article Immunology Inflammation

Transcription factor NFAT5 promotes macrophage survival in rheumatoid arthritis

Abstract

Defective apoptotic death of activated macrophages has been implicated in the pathogenesis of rheumatoid arthritis (RA). However, the molecular signatures defining apoptotic resistance of RA macrophages are not fully understood. Here, global transcriptome profiling of RA macrophages revealed that the osmoprotective transcription factor nuclear factor of activated T cells 5 (NFAT5) critically regulates diverse pathologic processes in synovial macrophages including the cell cycle, apoptosis, and proliferation. Transcriptomic analysis of NFAT5-deficient macrophages revealed the molecular networks defining cell survival and proliferation. Proinflammatory M1-polarizing stimuli and hypoxic conditions were responsible for enhanced NFAT5 expression in RA macrophages. An in vitro functional study demonstrated that NFAT5-deficient macrophages were more susceptible to apoptotic death. Specifically, CCL2 secretion in an NFAT5-dependent fashion bestowed apoptotic resistance to RA macrophages in vitro. Injection of recombinant CCL2 into one of the affected joints of Nfat5+/– mice increased joint destruction and macrophage infiltration, demonstrating the essential role of the NFAT5/CCL2 axis in arthritis progression in vivo. Moreover, after intra-articular injection, NFAT5-deficient macrophages were more susceptible to apoptosis and less efficient at promoting joint destruction than were NFAT5-sufficient macrophages. Thus, NFAT5 regulates macrophage survival by inducing CCL2 secretion. Our results provide evidence that NFAT5 expression in macrophages enhances chronic arthritis by conferring apoptotic resistance to activated macrophages.

Authors

Susanna Choi, Sungyong You, Donghyun Kim, Soo Youn Choi, H. Moo Kwon, Hyun-Sook Kim, Daehee Hwang, Yune-Jung Park, Chul-Soo Cho, Wan-Uk Kim

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Figure 10

Direct in vivo effect of NFAT5 in macrophages on the progression of arthritis.

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Direct in vivo effect of NFAT5 in macrophages on the progression of arth...
(A and B) Increase in arthritis severity by intra-articular injection of NFAT5-sufficient macrophages. Activated macrophages (5 × 105 cells per mouse) stimulated with LPS (10 mg/kg) in vivo for 24 hours were isolated from the spleens of Nfat5+/+ mice and then injected intra-articularly into the knee joints of Nfat5+/+ mice prior to injection of mBSA/IL-1β. The joint sections were stained with safranin O and macrophage marker Ab on day 7 to assess histological severity (A) and the degree of macrophage infiltration (B), respectively. Bar graphs show the mean ± SD of the histological grades and M scores (n = 5 per group). The rectangular areas in A are shown at higher magnification in B. *P < 0.01 and **P < 0.001, by Mann-Whitney U test. Scale bars: 200 μm (A) and 100 μm (B). (C and D) Increased apoptosis of macrophages in vivo due to NFAT5 deficiency. Activated splenic macrophages (5 × 105 cells) from Nfat5+/+ and Nfat5+/– mice were injected into the knee joints of Nfat5+/– mice before the injection of mBSA/IL-1β (n = 6 per group). Arthritic joints were stained with macrophage marker Ab (left panel in C), anti–active caspase 3 Ab (right panel in C), or safranin O (D) on day 7. Active caspase 3 staining was performed on 4-μm tissue sections next to those stained with macrophage marker Ab from the same joint. Bar graphs show the mean ± SD of histological grades assessed by safranin O staining (for the safranin O score, see the Supplemental Methods) and apoptosis scores. The apoptosis score was calculated as the staining frequency (percentage) with anti–active caspase 3 Ab multiplied by the intensity. *P < 0.05 and **P < 0.005, by Mann-Whitney U test. Scale bars: 200 μm (C) and 100 μm (D).