The anti-TNF-α antibody infliximab inhibits the expression of fat-transporter-protein FAT/CD36 in a selective hepatic-radiation mouse model.
Previously, we reported a radiation-induced inflammation triggering fat-accumulation through fatty-acid-translocase/cluster of differentiation protein 36 (FAT/CD36) in rat liver. Furthermore, inhibition of radiation-induced FAT/CD36-expression by anti-tumor necrosis factor-α (anti-TNF-α) (infliximab) was shown in vitro. The current study investigates fat-accumulation in a mouse-model of single-dose liver-irradiation (25-Gray) and the effect of anti-TNF-α-therapy on FAT/CD36 gene-expression. Mice livers were selectively irradiated in vivo in presence or absence of infliximab. Serum- and hepatic-triglycerides, mRNA, and protein were analyzed by colorimetric assays, RT-PCR, Immunofluorescence and Western-Blot, respectively. Sudan-staining was used demonstrating fat-accumulation in tissue. In mice livers, early (1-3 h) induction of TNF-α-expression, a pro-inflammatory cytokine, was observed. It was followed by elevated hepatic-triglyceride level (6-12 h), compared to sham-irradiated controls. In contrast, serum-triglyceride level was decreased at these time points. Similar to triglyceride level in mice livers, Sudan staining of liver cryosections showed a quick (6-12 h) increase of fat-droplets after irradiation. Furthermore, expression of fat-transporter-protein FAT/CD36 was increased at protein level caused by radiation or TNF-α. TNF-α-blockage by anti-TNF-α showed an early inhibition of radiation-induced FAT/CD36 expression in mice livers. Immunohistochemistry showed basolateral and cytoplasmic expression of FAT/CD36 in hepatocytes. Moreover, co-localization of FAT/CD36 was detected with α-smooth muscle actin (α-SMA+) cells and F4/80+ macrophages. In summary, hepatic-radiation triggers fat-accumulation in mice livers, involving acute-phase-processes. Accordingly, anti-TNF-α-therapy prevented early radiation-induced expression of FAT/CD36 in vivo.
Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Robert-Koch-Strasse 40, Goettingen 37075, Niedersachsen, Germany. gesa.martius@med.uni-goettingen.de.
Gesa
G
Martius
Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Robert-Koch-Strasse 40, Goettingen 37075, Niedersachsen, Germany. silke.cameron@med.uni-goettingen.de.
Silke
S
Cameron
Department of Radiotherapy and Radiooncology, University Medical Center Goettingen, Robert-Koch-Strasse 40, Goettingen 37075, Niedersachsen, Germany. mfraenk@med.uni-goettingen.de.
Margret
M
Rave-Fränk
Department of Radiotherapy and Radiooncology, University Medical Center Goettingen, Robert-Koch-Strasse 40, Goettingen 37075, Niedersachsen, Germany. cfhess@med.uni-goettingen.de.
Clemens F
CF
Hess
Department of Radiotherapy and Radiooncology, University Medical Center Goettingen, Robert-Koch-Strasse 40, Goettingen 37075, Niedersachsen, Germany. hendrik.wolff@med.uni-goettingen.de.
Hendrik A
HA
Wolff
Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Robert-Koch-Strasse 40, Goettingen 37075, Niedersachsen, Germany. i.malik@med.uni-goettingen.de.
Ihtzaz A
IA
Malik
D000818:Animals; D015153:Blotting, Western; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism*; D005223:Fats / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000528:radiation effects; D000069285:Infliximab / Q000276:immunology / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D023421:Models, Animal; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000097:blood / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D018955:CD36 Antigens; D005223:Fats; D014280:Triglycerides; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab