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Lack of CC chemokine ligand 2 differentially affects inflammation and fibrosis according to the genetic background in a murine model of steatohepatitis.

Galastri S, Zamara E, Milani S, Novo E, Provenzano A, Delogu W, Vizzutti F, Sutti S, Locatelli I, Navari N, Vivoli E, Caligiuri A, Pinzani M, Albano E, Parola M, Marra F - Clin. Sci. (2012)

Bottom Line: Sirius Red staining demonstrated pericellular fibrosis in zone 3, and image analysis showed a significantly lower matrix accumulation in CCL2-KO mice.This was associated with reduced hepatic expression of TGF-β (transforming growth factor-β), type I procollagen, TIMP-1 (tissue inhibitor of metalloproteinases-1) and α-smooth muscle actin.We conclude that, in experimental murine steatohepatitis, the effects of CCL2 deficiency are markedly dependent on the genetic background.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Medicina Interna, University of Florence, Florence, Italy.

ABSTRACT
Expression of CCL2 (CC chemokine ligand 2) (or monocyte chemoattractant protein-1) regulates inflammatory cell infiltration in the liver and adipose tissue, favouring steatosis. However, its role in the pathogenesis of steatohepatitis is still uncertain. In the present study, we investigated the development of non-alcoholic steatohepatitis induced by an MCD diet (methionine/choline-deficient diet) in mice lacking the CCL2 gene on two different genetic backgrounds, namely Balb/C and C57/Bl6J. WT (wild-type) and CCL2-KO (knockout) mice were fed on a lipid-enriched MCD diet or a control diet for 8 weeks. In Balb/C mice fed on the MCD diet, a lack of CCL2 was associated with lower ALT (alanine transaminase) levels and reduced infiltration of inflammatory cells, together with a lower generation of oxidative-stress-related products. Sirius Red staining demonstrated pericellular fibrosis in zone 3, and image analysis showed a significantly lower matrix accumulation in CCL2-KO mice. This was associated with reduced hepatic expression of TGF-β (transforming growth factor-β), type I procollagen, TIMP-1 (tissue inhibitor of metalloproteinases-1) and α-smooth muscle actin. In contrast, in mice on a C57Bl/6 background, neither ALT levels nor inflammation or fibrosis were significantly different comparing WT and CCL2-KO animals fed on an MCD diet. In agreement, genes related to fibrogenesis were expressed to comparable levels in the two groups of animals. Comparison of the expression of several genes involved in inflammation and repair demonstrated that IL (interleukin)-4 and the M2 marker MGL-1 (macrophage galactose-type C-type lectin 1) were differentially expressed in Balb/C and C57Bl/6 mice. No significant differences in the degree of steatosis were observed in all groups of mice fed on the MCD diet. We conclude that, in experimental murine steatohepatitis, the effects of CCL2 deficiency are markedly dependent on the genetic background.

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Differential expression of genes involved in inflammation and immune response in mice with a different genetic background fed on the MCD dietWT or CCL2-KO mice on a Balb/C (A, C, E, G, I) or C57Bl/6 (B, D, F, H, J) genetic background were fed for 8 weeks on the control diet or on the MCD diet. At the end of the study protocol, RNA was isolated from liver tissue and the expression of IFN-γ (A,B), IL-4 (C,D), CCL5 (E,F), iNOS (G,H) or MGL1 (I,J) was assayed by RT-PCR. *P<0.01 compared with WT animals fed on the control diet; **P<0.01 compared with WT animals fed on the MCD diet.
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Figure 7: Differential expression of genes involved in inflammation and immune response in mice with a different genetic background fed on the MCD dietWT or CCL2-KO mice on a Balb/C (A, C, E, G, I) or C57Bl/6 (B, D, F, H, J) genetic background were fed for 8 weeks on the control diet or on the MCD diet. At the end of the study protocol, RNA was isolated from liver tissue and the expression of IFN-γ (A,B), IL-4 (C,D), CCL5 (E,F), iNOS (G,H) or MGL1 (I,J) was assayed by RT-PCR. *P<0.01 compared with WT animals fed on the control diet; **P<0.01 compared with WT animals fed on the MCD diet.

Mentions: To investigate the mechanisms underlying the different inflammatory and fibrogenic response observed in the two strains of mice upon CCL2 deletion, we first investigated a group of cytokines involved in immune response and inflammation. The levels of IFN-γ (interferon-γ), which promotes inflammation and is associated with a lower fibrogenic response, were reduced by the MCD diet in both Balb/C and C57Bl/6 mice, and no effects of CCL2 deletion were observed (Figures 7A and 7B). In contrast, the expression of IL (interleukin)-4, a cytokine related to Th2 polarization, was reduced in Balb/C mice fed on the MCD diet, and the reduction was more evident in the absence of CCL2 (Figure 7C). In contrast, in C57Bl/6 mice, the levels of IL-4 were higher in animals lacking CCL2 when fed on the MCD diet (Figure 7D).


Lack of CC chemokine ligand 2 differentially affects inflammation and fibrosis according to the genetic background in a murine model of steatohepatitis.

Galastri S, Zamara E, Milani S, Novo E, Provenzano A, Delogu W, Vizzutti F, Sutti S, Locatelli I, Navari N, Vivoli E, Caligiuri A, Pinzani M, Albano E, Parola M, Marra F - Clin. Sci. (2012)

Differential expression of genes involved in inflammation and immune response in mice with a different genetic background fed on the MCD dietWT or CCL2-KO mice on a Balb/C (A, C, E, G, I) or C57Bl/6 (B, D, F, H, J) genetic background were fed for 8 weeks on the control diet or on the MCD diet. At the end of the study protocol, RNA was isolated from liver tissue and the expression of IFN-γ (A,B), IL-4 (C,D), CCL5 (E,F), iNOS (G,H) or MGL1 (I,J) was assayed by RT-PCR. *P<0.01 compared with WT animals fed on the control diet; **P<0.01 compared with WT animals fed on the MCD diet.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369401&req=5

Figure 7: Differential expression of genes involved in inflammation and immune response in mice with a different genetic background fed on the MCD dietWT or CCL2-KO mice on a Balb/C (A, C, E, G, I) or C57Bl/6 (B, D, F, H, J) genetic background were fed for 8 weeks on the control diet or on the MCD diet. At the end of the study protocol, RNA was isolated from liver tissue and the expression of IFN-γ (A,B), IL-4 (C,D), CCL5 (E,F), iNOS (G,H) or MGL1 (I,J) was assayed by RT-PCR. *P<0.01 compared with WT animals fed on the control diet; **P<0.01 compared with WT animals fed on the MCD diet.
Mentions: To investigate the mechanisms underlying the different inflammatory and fibrogenic response observed in the two strains of mice upon CCL2 deletion, we first investigated a group of cytokines involved in immune response and inflammation. The levels of IFN-γ (interferon-γ), which promotes inflammation and is associated with a lower fibrogenic response, were reduced by the MCD diet in both Balb/C and C57Bl/6 mice, and no effects of CCL2 deletion were observed (Figures 7A and 7B). In contrast, the expression of IL (interleukin)-4, a cytokine related to Th2 polarization, was reduced in Balb/C mice fed on the MCD diet, and the reduction was more evident in the absence of CCL2 (Figure 7C). In contrast, in C57Bl/6 mice, the levels of IL-4 were higher in animals lacking CCL2 when fed on the MCD diet (Figure 7D).

Bottom Line: Sirius Red staining demonstrated pericellular fibrosis in zone 3, and image analysis showed a significantly lower matrix accumulation in CCL2-KO mice.This was associated with reduced hepatic expression of TGF-β (transforming growth factor-β), type I procollagen, TIMP-1 (tissue inhibitor of metalloproteinases-1) and α-smooth muscle actin.We conclude that, in experimental murine steatohepatitis, the effects of CCL2 deficiency are markedly dependent on the genetic background.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Medicina Interna, University of Florence, Florence, Italy.

ABSTRACT
Expression of CCL2 (CC chemokine ligand 2) (or monocyte chemoattractant protein-1) regulates inflammatory cell infiltration in the liver and adipose tissue, favouring steatosis. However, its role in the pathogenesis of steatohepatitis is still uncertain. In the present study, we investigated the development of non-alcoholic steatohepatitis induced by an MCD diet (methionine/choline-deficient diet) in mice lacking the CCL2 gene on two different genetic backgrounds, namely Balb/C and C57/Bl6J. WT (wild-type) and CCL2-KO (knockout) mice were fed on a lipid-enriched MCD diet or a control diet for 8 weeks. In Balb/C mice fed on the MCD diet, a lack of CCL2 was associated with lower ALT (alanine transaminase) levels and reduced infiltration of inflammatory cells, together with a lower generation of oxidative-stress-related products. Sirius Red staining demonstrated pericellular fibrosis in zone 3, and image analysis showed a significantly lower matrix accumulation in CCL2-KO mice. This was associated with reduced hepatic expression of TGF-β (transforming growth factor-β), type I procollagen, TIMP-1 (tissue inhibitor of metalloproteinases-1) and α-smooth muscle actin. In contrast, in mice on a C57Bl/6 background, neither ALT levels nor inflammation or fibrosis were significantly different comparing WT and CCL2-KO animals fed on an MCD diet. In agreement, genes related to fibrogenesis were expressed to comparable levels in the two groups of animals. Comparison of the expression of several genes involved in inflammation and repair demonstrated that IL (interleukin)-4 and the M2 marker MGL-1 (macrophage galactose-type C-type lectin 1) were differentially expressed in Balb/C and C57Bl/6 mice. No significant differences in the degree of steatosis were observed in all groups of mice fed on the MCD diet. We conclude that, in experimental murine steatohepatitis, the effects of CCL2 deficiency are markedly dependent on the genetic background.

Show MeSH
Related in: MedlinePlus