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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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CCL2 deficiency does not affect aminotransferase levels and inflammation following administration of an MCD diet in C57Bl/6 miceWT or CCL2-KO mice were fed for 8 weeks on the control diet or the MCD diet. Groups are as in the legend to Figure 1. (A) Serum ALT was assayed as described in Materials and methods section. (B) Individual necro-inflammatory scores in the four groups of mice. (C) RNA was isolated from liver tissue, and expression of CD11b was measured by RT-PCR. U, units.
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Figure 5: CCL2 deficiency does not affect aminotransferase levels and inflammation following administration of an MCD diet in C57Bl/6 miceWT or CCL2-KO mice were fed for 8 weeks on the control diet or the MCD diet. Groups are as in the legend to Figure 1. (A) Serum ALT was assayed as described in Materials and methods section. (B) Individual necro-inflammatory scores in the four groups of mice. (C) RNA was isolated from liver tissue, and expression of CD11b was measured by RT-PCR. U, units.

Mentions: Recently, Kassel et al. [15] investigated the development of MCD-induced steatohepatitis in CCL2-KO mice raised on a C57Bl/6 background, without detecting significant differences in hepatic injury and inflammation compared with WT mice. Since our findings obtained in Balb/C mice demonstrate that CCL2 deficiency protects from necro-inflammation and fibrosis, we also analysed the effects of MCD feeding for 8 weeks and CCL2 deficiency in C57Bl/6 mice. In these mice, ALT levels were elevated to a higher extent than in Balb/C mice (approximately 7-fold). However, CCL2 deficiency did not result in any significant changes in ALT levels (Figure 5A). In agreement with this observation, steatosis (results not shown) and necro-inflammation (Figure 5B) evaluated by histological scoring were not significantly different when comparing the two genotypes. Moreover, intrahepatic expression of the inflammatory marker CD11b was increased to a similar extent in mice fed on the MCD diet irrespective of the absence of CCL2 (Figure 5C).


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)

CCL2 deficiency does not affect aminotransferase levels and inflammation following administration of an MCD diet in C57Bl/6 miceWT or CCL2-KO mice were fed for 8 weeks on the control diet or the MCD diet. Groups are as in the legend to Figure 1. (A) Serum ALT was assayed as described in Materials and methods section. (B) Individual necro-inflammatory scores in the four groups of mice. (C) RNA was isolated from liver tissue, and expression of CD11b was measured by RT-PCR. U, units.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: CCL2 deficiency does not affect aminotransferase levels and inflammation following administration of an MCD diet in C57Bl/6 miceWT or CCL2-KO mice were fed for 8 weeks on the control diet or the MCD diet. Groups are as in the legend to Figure 1. (A) Serum ALT was assayed as described in Materials and methods section. (B) Individual necro-inflammatory scores in the four groups of mice. (C) RNA was isolated from liver tissue, and expression of CD11b was measured by RT-PCR. U, units.
Mentions: Recently, Kassel et al. [15] investigated the development of MCD-induced steatohepatitis in CCL2-KO mice raised on a C57Bl/6 background, without detecting significant differences in hepatic injury and inflammation compared with WT mice. Since our findings obtained in Balb/C mice demonstrate that CCL2 deficiency protects from necro-inflammation and fibrosis, we also analysed the effects of MCD feeding for 8 weeks and CCL2 deficiency in C57Bl/6 mice. In these mice, ALT levels were elevated to a higher extent than in Balb/C mice (approximately 7-fold). However, CCL2 deficiency did not result in any significant changes in ALT levels (Figure 5A). In agreement with this observation, steatosis (results not shown) and necro-inflammation (Figure 5B) evaluated by histological scoring were not significantly different when comparing the two genotypes. Moreover, intrahepatic expression of the inflammatory marker CD11b was increased to a similar extent in mice fed on the MCD diet irrespective of the absence of CCL2 (Figure 5C).

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