Taurine ameliorates cellular senescence associated with an increased hydrogen sulfide and a decreased hepatokine, IGFBP-1, in CCl4-induced hepatotoxicity in mice

Abstract

This study investigated the protective effects of taurine against cellular senescence and hepatokine secretion in a mouse model of carbon tetrachloride (CCl4)-induced chronic liver injury. Oral taurine administration by tap water containing 3 % taurine significantly attenuated liver damage, as evidenced by reduced serum AST, ALT level and hepatic lipid peroxidation. Importantly, hepatic taurine level is reduced in CCl4-induced injury model, while taurine administration recovered it. Moreover, taurine administration decreased the numbers of p21-positive senescent cells in liver tissue of CCl4-treated mice. Taurine increases hydrogen sulfide (H₂S) in liver of normal mice, suggesting anti-oxidative role through H₂S production by taurine. Furthermore, inhibition of CTH, which is an enzyme responsible for H₂S production from cysteine, by propagylglycine attenuated malondialdehyde-lowering effect of taurine in liver of CCl4-treated mice. Moreover, we found taurine treatment lowers insulin-like growth factor binding protein-1 (IGFBP-1) in liver of normal mice. Importantly, while chronic CCl4 injection caused an induction of IGFBP-1, taurine administration blocked it. These findings suggest that taurine exerts its protective effects by attenuating cellular senescence, which is associated with enhancing H₂S production and inhibiting IGFBP-1 expression. This study highlights the potential of taurine as a therapeutic strategy for mitigating chronic liver injury by producing H₂S and targeting IGFBP1.

Keywords: Hepatokines; Hydrogen sulfide; IGFBP-1; Liver injury; Senescence; Taurine.

Graphical abstract

Fig. 1

Effect of Taurine on the toxicity induced by chronic CCl4 injection. (A) Flowchart of treatment group. (B)The changes in body weight after CCl4 injection with taurine drinking. Body weight was monitored after CCl4 injection. Taurine treatment by drinking water was started from 4th week of CCl4 administration indicated by arrow. n = 4. (C,D) Hepatic MDA level (C) and taurine concentration (D) were measured. Values shown represent means ± SD. n = 4. ∗∗p < 0.01 (post-hoc Bonferroni test). Similar results were observed in another independent experiment as shown in supplemental material.

Fig. 2

Effect of taurine on the cellular senescence induced by chronic CCl4 injection. (A) p21 expression was measured in the liver by qPCR. The expression level was normalized by the expression level of 28S ribosomal RNA. Values are shown fold of Control. n = 6–8. ∗p < 0.05 (post-hoc Bonferroni test). (B) Frozen section of livers was immunostained with anti-p21and anti-p16 antibodies. Arrowheads indicate positive cells. Positive cells per microscopic images were calculated from 5 images per samples for 4 samples for each group. ∗p < 0.05 (Student's t-test).

Fig. 3

Effect of taurine on cysteine metabolism in liver. (A) Heat maps showing the differentially expressed genes (p < 0.05) which are related to cysteine metabolism in the liver between taurine-treated and control mice, as assessed by microarray previously performed. (B) CSAD and CTH were analyzed by Western blot and band intensity was calculated. The intensity was normalized by the GAPDH level. n = 4. ∗p < 0.05 (student's t-test). (C–F) Hepatic taurine, cystine, H₂S and sulfane sulfur were measured. Values were normalized by tissue weight (g). n = 8 (taurine, cysteine, H₂S), 4 (sulfane sulfur). ∗p < 0.05 (student's t-test). (G) Pathway of cysteine metabolism was shown. Red (increase) and blue (decrease) arrows indicate the effect.

Fig. 4

Effect of taurine on cysteine metabolism changes induced by CCl4 injection in liver. (A–C) Hepatic cystine, H₂S and GSH were measured. Values were normalized by tissue weight (g). n = 4 (cystine), 4 (H₂S, GSH). ∗p < 0.05, ∗∗p < 0.01 (post-hoc Bonferroni test). Similar results were observed for cysteine measurement in another independent experiment as shown in supplemental material.

Fig. 5

Effect of taurine and PPG on the liver damage induced by CCl4 injection. (A) Time course of CCl4, taurine and PPG injection. (B) Hepatic MDA level were measured. Values shown represent means ± SD. n = 4. ∗p < 0.05, ∗∗p < 0.01 (post-hoc Tukey-HSD test). (C–D) Serum ALT and AST level were measured. n = 4. ∗p < 0.05, ∗∗p < 0.01 (post-hoc Tukey-HSD test). Additionally, data from CCl4+taurine (CCl4+T) and CCl4+taurine + PPG (CCl4+T + P)-treated group were picked up into the accompanied scattered graph.

Fig. 6

Effect of taurine on TGF−β1 and IGFBP-1 expression in liver. (A) mRNA of TGF−β1 was measured by qPCR. The expression level was normalized by the expression level of 28S ribosomal RNA. Values are shown fold of Control. n = 6–8. (B) Igfbp-1 mRNA expression was measured by qPCR. The expression level was normalized by the expression level of 28S ribosomal RNA. Values are shown fold of Control. ∗p < 0.05 (Student's t-test). (C–E) The effect of CCl4 and taurine on Igfbp-1 mRNA (C), protein (D) in liver and serum IGFBP-1 protein (E) were analyzed. n = 4–8. ∗p < 0.05, ∗∗p < 0.01 (post-hoc Tukey-HSD test).

Fig. 7

Potential mechanisms underlying anti-senescent role of taurine.

Fig. S1

Effect of Taurine on the toxicity induced by chronic CCl4 injection in second CCl4 experiment. (A) Hepatic MDA level (B) taurine and (C) cysteine concentration. Values shown represent means ± SD. n = 2–4.

Fig. S2

Effect of taurine on SASP factor expression induced by chronic CCl4 injection. Cytokine expressions were measured in the liver by qPCR. The expression level was normalized by the expression level of 28S ribosomal RNA. Values are shown fold of Control. n = 4.

Fig. S3

Effect of taurine on fibrosis induced by chronic CCl4 injection. (A) Representative image from Picrosirius red stain. (B) Collagen gene expressions were measured in the liver by qPCR. The expression level was normalized by the expression level of 28S ribosomal RNA. Values are shown fold of Control. n = 4.

Fig. S4

Raw IHC images for p21 in liver sections.

Fig. S5

Rraw western blot images.