3.2 PB ameliorated CCl4-induced liver injury and
hepatic fibrosis in mice
In order to evaluate whether large doses of PB has any hepatotoxicity,
mice
were intraperitoneal injection of PB 40mg/kg. HE staining, Sirius red
staining and Masson staining showed that PB (40mg/kg) did not cause any
pathological or fibrous damage (Supplementary Fig. 1B). Mice were
intraperitoneal injection with 2% DMSO as the vehicle group. Similarly,
HE staining, Sirius red staining and Masson staining showed that 2%
DMSO did not cause any pathological or fibrous damage (Supplementary
Fig. 1C). Based on these results,
we next evaluated the anti-hepatic fibrosis effect of PB in mouse
fibrosis models in vivo .
Carbon tetrachloride (CCl4) is a hepatotoxin that has
been used extensively to induce liver injury. It induces liver fibrosis
by producing various reactive metabolites and damaging hepatocytes. To
assess the pharmaceutical activities of PB in vivo , we performed
CCl4 challenge in mice. After 4 weeks of
CCl4 injections, the mice exhibited marked increases in
hepatic inflammatory cell infiltration, mild thickening of the central
venous wall and fibrous hyperplasia. However, PB treatment ameliorated
these pathological changes and protected against
CCl4‐induced fibrosis (Figure 2A). Serum ALT and AST
levels were significantly elevated in
the
CCl4-treated mice, while decreased in PB treated group
indicating improved liver injury (Figure 2B). The severity of liver
fibrosis was also biochemically assessed by measuring the hepatic
hydroxyproline content. PB markedly decreased the
CCl4-induced increase of hydroxyproline content (Figure
2C). Sirius red and Masson’s trichrome staining visualizes collagen,
which is used to evaluate the degree and characteristics of fibrosis.
Sirius Red, Masson’s trichrome stained liver sections indicated that
fibrous collagen deposition, fibroplasia, and bridging fibrosis
significantly decreased in PB treated mice (Figure 2D). The expression
of hepatic fibrogenic markers, including αsma , Col1a1 ,Tgfb1 and tissue inhibitor of metalloproteinase 1(Timp1 )
were detected to assess the antifibrotic effects of PB in vivo .
PB treatment significantly decreased the mRNA expression of these
fibrogenic genes. Western blot assays also validated that PB treatment
decreased α‐SMA and COL1A1 expression in the liver tissues (Figure 2E,
F). Accordingly, PB has the potential to inhibit the progression of
CCl4-induced hepatic fibrosis in mice.