Fragile TIM-4–expressing tissue resident macrophages are migratory and immunoregulatory
Thomas B. Thornley, … , Vijay K. Kuchroo, Terry B. Strom
Thomas B. Thornley, … , Vijay K. Kuchroo, Terry B. Strom
Published July 1, 2014
Citation Information: J Clin Invest. 2014;124(8):3443-3454. https://doi.org/10.1172/JCI73527.
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Research Article Immunology

Fragile TIM-4–expressing tissue resident macrophages are migratory and immunoregulatory

Abstract

Macrophages characterized as M2 and M2-like regulate immune responses associated with immune suppression and healing; however, the relationship of this macrophage subset to CD169+ tissue-resident macrophages and their contribution to shaping alloimmune responses is unknown. Here we identified a population of M2-like tissue-resident macrophages that express high levels of the phosphatidylserine receptor TIM-4 and CD169 (TIM-4hiCD169+). Labeling and tracking of TIM-4hiCD169+ macrophages in mice revealed that this population is a major subset of tissue-resident macrophages, homes to draining LNs following oxidative stress, exhibits an immunoregulatory and hypostimulatory phenotype that is maintained after migration to secondary lymphoid organs, favors preferential induction of antigen-stimulated Tregs, and is highly susceptible to apoptosis. Moreover, CD169+ tissue-resident macrophages were resistant to oxidative stress–induced apoptosis in mice lacking TIM-4. Compared with heart allografts from WT mice, Tim4–/– heart allografts survived much longer and were more easily tolerized by non-immunosuppressed recipients. Furthermore, Tim4–/– allograft survival was associated with the infiltration of Tregs into the graft. Together, our data provide evidence that M2-like TIM-4hiCD169+ tissue-resident macrophages are immunoregulatory and promote engraftment of cardiac allografts, but their influence is diminished by TIM-4–dependent programmed cell death.

Authors

Thomas B. Thornley, Zemin Fang, Savithri Balasubramanian, Rafael A. Larocca, Weihua Gong, Shipra Gupta, Eva Csizmadia, Nicolas Degauque, Beom Seok Kim, Maria Koulmanda, Vijay K. Kuchroo, Terry B. Strom

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Figure 1

A subpopulation of skin-resident CD11b+F4/80+CD169+ tissue-resident macrophages with an immunoregulatory phenotype coexpresses TIM-4.

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A subpopulation of skin-resident CD11b+F4/80+CD169+ tissue-resident macr...
Intradermal leukocytes were obtained from the skin of untreated C57BL/6 mice following collagenase digestion. Cells were stained with DAPI, anti-CD45, anti-F4/80, anti-CD11b, anti-CD169, and anti-Ly6C. (A) Using a sequential gating strategy, we gated on live (DAPI–) CD45+ cells (not shown) and then identified F4/80+CD11b+ cells that were then subdivided into Ly6C– subpopulations that were CD169+ and CD169–. (B) DAPI– CD11b+F4/80+Ly6C–CD169+ and DAPI– CD11b+F4/80+Ly6C–CD169– subsets of intradermal leukocytes were selected and assessed for the expression of TIM-4, CD39, CD73, and galectin-9 using the gating scheme shown in A. Shaded histograms represent fluorescence minus one (FMO) controls or anti–TIM-4–stained Tim4–/– skin macrophages. MFIs are noted parenthetically. (C) The CD169–, TIM-4–/loCD169+, and TIM-4hiCD169+ subsets of the CD11b+F4/80+Ly6C– population from A and B were cell sorted and analyzed by real-time PCR using the listed Taqman probes and primers. As expected, Tim4 mRNA was expressed at high levels only in the TIM-4hiCD169+ subpopulation (P < 0.01 among the 3 groups, 1-way repeated-measures ANOVA). Tgfb mRNA significantly differed between the TIM-4hiCD169+ subpopulation and both TIM-4–/lo subsets. **P < 0.01, 1-way repeated-measures ANOVA (P < 0.01) with Bonferroni post-test. Graphs represent mean ± SD from 7 unique animals from 3 independent experiments.