Acute Inflammation Initiates the Regenerative Response in the Adult Zebrafish Brain
Nikos Kyritsis1,
Caghan Kizil1,
Sara Zocher1,
Volker Kroehne1,
Jan Kaslin1,2,
Dorian Freudenreich1,
Anne Iltzsche1, and
Michael Brand1,*
1 Deutsche Forshungsgemeinschaft–Center for Regenerative Therapies Dresden (CRTD)–Cluster of Excellence, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany.
2 Australian Regenerative Medicine Institute (ARMI), Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
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Fig. 1. Leukocytes infiltrate the brain rapidly after traumatic injury and sterile infection. (A and B) Immunohistochemistry (IHC) for L-plastin in unlesioned and lesioned telencephalons. (C) Quantification of the L-plastin cells in sham-operated, lesioned, and unlesioned telencephalic hemispheres in time course. (D and E) IHC for L-plastin in phosphate-buffered saline (PBS)– and zymosan A–injected brains. (F) Quantification of the L-plastin cells in PBS- and zymosan A–injected brains in time course. ns, not significant; **P < 0.01, ***P < 0.001; scale bars, 100 μm; n = 3 brains for every experiment.
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Fig. 2. Inflammation is sufficient and necessary for the initiation of reactive proliferation and reactive neurogenesis. (A and B) IHC for S100β and PCNA in PBS- or zymosan A–injected zebrafish brains. (C) Quantification of S100β/PCNA-positive cells in PBS and zymosan A–injected brains. (D and E) IHC for HuC/D and BrdU. (F) Quantification of the HuC/D/BrdU double-positive cells between PBS and zymosan A injections. (G and H) IHC for S100β and PCNA. (I) Quantification of proliferating radial glia in both lesioned and unlesioned hemispheres between Dex- and vehicle-treated animals. (J and K) IHC for HuC/D and BrdU. (L) Quantification of the newborn neurons (HuC/D/BrdU double-positive cells). *P < 0.05, **P < 0.01, ***P < 0.001; scale bars, 100 μm; n = 4 brains for every experiment.
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Fig. 3. The CysLT1–LTC4 pathway is required and sufficient for enhanced proliferation and neurogenesis. (A) cysltr1 expression is up-regulated in the lesioned hemisphere at the ventricular zone at 3 days after lesion. (B) IHC shows that CysLT1 is expressed in radial glial cells. (C and D) cysltr1 is up-regulated significantly at the ventricular zone after zymosan A injections. (E and F) IHC for S100β and PCNA. (G) Quantification of S100β/PCNA-positive cells in dimethyl sulfoxide (DMSO)– and Pranlukast-injected brains. (H and I) IHC for HuC/D and BrdU. (J) Quantification of HuC/D/BrdU-positive cells in DMSO- and Pranlukast-injected brains. (K and L) IHC for S100β and PCNA in MetOH- and LTC4-injected brains (M) LTC4 injections initiate the reactive proliferation response. (N and O) IHC for HuC/D and BrdU. (P) LTC4 injections induce reactive neurogenesis. *P < 0.05, **P < 0.01, ***P < 0.001; scale bar in (A), 200 μm; scale bar in (B), 10 μm; scale bars in (C), (D), (K), (L), (N), and (O), 100 μm; dashed circle in (A) indicates the lesion site; n = 3 brains for every experiment.
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Fig. 4. Inflammation is sufficient and necessary for inducing regeneration-specific molecular programs. (A and B) gata3 is induced at the ventricular zone 24 hours after zymosan A injections in comparison to vehicle injections. (C) Relative fold change of gata3 expression between vehicle and zymosan A injections. (D) Relative expression levels of gata3 at 3 days after lesion in immunosuppressed and control animals. (E and F) gata3 is induced significantly in the ventricular region 24 hours after LTC4 injection, in comparison to vehicle-injected brains. (G) Relative expression levels of gata3 in vehicle- and LTC4-injected brains. (H) Quantification graph indicates that gata3 expression reduces significantly after Pranlukast injection, in comparison to vehicle-injected telencephalons. *P < 0.05, **P < 0.01, ***P < 0.001; scale bars, 100 μm; n = 3 brains for every experiment).
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