Dietary long-chain polyunsaturated fatty acids influence the recovery of thioacetamide-induced liver cirrhosis in rats

AdhMMP8 Vector Administration in Muscle: An Alternate Strategy to Regress Hepatic Fibrosis

The development of several vaccines against the SARS-CoV2 virus and their application in millions of people have shown efficacy and safety in the transfer of genes to muscle turning this tissue into a protein-producing factory. Established advanced liver fibrosis, is characterized by replacement of hepatic parenchyma by tissue scar, mostly collagen type I, with increased profibrogenic and proinflammatory molecules gene expression. Matrix metalloproteinase 8 (MMP-8) is an interstitial collagen-degrading proenzyme acting preferentially on collagen type I when activated. This study was carried out to elucidate the effect of an intramuscularly delivered adenoviral vector containing proMMP-8 gene cDNA (AdhMMP8) in male Wistar rats with experimental advanced liver fibrosis induced by thioacetamide. Therapeutic effects were monitored after 1, 2, or 3 weeks of a single dose (3 × 1011 vp/kg) of AdhMMP8. Circulating and liver concentration of MMP-8 protein remained constant; hepatic fibrosis decreased up to 48%; proinflammatory and profibrogenic genes expression diminished: TNF-α 2.28-fold, IL-1 1.95-fold, Col 1A1 4-fold, TGF-β1 3-fold and CTGF 2-fold; and antifibrogenic genes expression raised, MMP-9 2.8-fold and MMP-1 10-fold. Our data proposes that the administration of AdhMMP8 in muscle is safe and effective in achieving liver fibrosis regression at a comparable extent as when the adenoviral vector is delivered systemically to reach the liver, using a minimally invasive procedure.

Docosahexaenoic acid attenuates carbon tetrachloride-induced hepatic fibrosis in rats

Fish oil containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) has been reported to exert beneficial health effects, including hepatoprotection. However, the effect of DHA alone has not been well studied, and the mechanism is not fully understood. In the present study, we reported the protective effect of DHA on carbon tetrachloride (CCl₄) induced hepatic fibrosis. Compared with the control group, the CCl₄ group showed hepatic damage as evidenced by histological changes and elevation in serum transaminase activity, fibrosis, inflammation and oxidative stress levels. These pathophysiological changes were attenuated by chronic DHA supplementation. The anti-fibrotic effect of DHA was accompanied by reductions in gene and protein expression of α-smooth muscle actin (α-SMA), fibronectin, and collagen in the liver tissue. DHA also attenuated CCl₄-induced elevation of lipid peroxidation (LPO) and decrease of glutathione (GSH)/oxidized GSH (GSSG) ratio. The upregulated inflammatory cytokines tumor necrosis factor (TNF)-α, interferon (IFN)-γ and interleukin (IL)-6 by CCl₄ were also ameliorated by DHA. Peroxisome proliferator-activated receptor (PPAR)-γ upregulation and type I and II receptors for transforming growth factor (TGF)-β (Tβ-RI and Tβ-RII) and platelet-derived growth factor (PDGF)-β receptor (PDGF-βR) downregulation on both mRNA and protein levels were observed by DHA treatment compared to CCl₄ group. Moreover, in vitro study showed that DHA inhibited HSC activation, being associated with elevating PPARγ level and reducing the phosphorylation levels of Smad2/3 and ERKs, which are downstream intermediates of TGFβ and PDGF receptors, respectively. Taken together, the hepatoprotective, anti-inflammatory and anti-fibrotic effects of DHA appeared to be multifactorial. Further, one of the mechanisms of the anti-fibrotic effect of chronic DHA supplementation is probably through PPARγ signaling to interrupt TGFβ/Smad and PDGF/ERK pathways in HSCs.

Dietary supplementation with monounsaturated and long-chain polyunsaturated fatty acids influences the liver structural recovery and hepatocyte binuclearity in female Wistar rats in experimental cirrhosis induced by thioacetamide

Oral administration of 300 mg/l thioacetamide (TAA) for 4 months causes hepatic lesions comparable to those described in alcoholic liver cirrhosis in humans and associated protein-energy malnutrition. In this sense, direct supplementation with monounsaturated fatty acids (MUFAs) and/or polyunsaturated fatty acids (PUFAs) might provide an advantage in the correction of the fatty acid deficiency in these patients. PUFAs are essential components of cell membranes maintaining its fluidity and function, important energy sources, and precursors of eicosanoids. Moreover, these fatty acids also modulate gene transcription, mRNA stability, and cellular differentiation.

METHODS

Fifty-four female Wistar rats (Interfauna Ibérica, Barcelona, Spain) weighing 110-120 g were used in this study. The animals were divided into two groups: one group was treated with 300 mg/l TAA dissolved in drinking water during 4 months, and the other group, which served as a control, was given water without TAA. To evaluate the changes induced by the administration of TAA for 4 months, TAA-treated (n = 7) and control animals (n = 5) were killed. Then, the TAA treatment was stopped and the rest of the animals in both TAA and control groups were divided into three experimental groups and three control groups which received for 2 weeks different type of diets. Using the TAA-induced liver cirrhosis model in rats, we analysed the effects of dietary supplementation with MUFAs and PUFAs on binuclearity and ultrastructure of hepatocytes. After TAA-induced cirrhosis, we analysed whether dietary supplementation with fatty acids may restore the normal percentage of binucleated cells, as well as the ultrastructure, nuclear area, and nuclear/cytoplasm index of hepatocytes.

RESULTS

Treatment with TAA causes cirrhosis characterized by the appearance of parenchyma nodules and fibrous septae, as well as qualitative and quantitative alterations in liver and plasma lipids. Our results indicate that dietary MUFAs support hepatocyte recovery regarding its ultrastructural and morphometric values. However, PUFAs-enriched diets (n-3 and n-3 + n-6) do not correct hepatomegaly, fibrosis or lipid accumulation. Thus, dietary PUFAs do not enhance hepatocyte recovery from morphological and ultrastructural alterations.

CONCLUSIONS

In our experimental model of cirrhosis, dietary supplementation with a high proportion of long-chain PUFAs (n-3 or n-6) negatively influences liver recovery. This negative effect was likely due to the increased susceptibility of cell membranes to lipid peroxidation, together with an alteration in lipid metabolism.

Steatosis and collagen content in experimental liver cirrhosis are affected by dietary monounsaturated and polyunsaturated fatty acids

BACKGROUND AND METHODS

We used thioacetamide administered orally to induce cirrhosis in rats, and after these had recovered for 1 and 2 weeks we examined the effects of dietary supplementation with monounsaturated and n-3 polyunsaturated fatty acids, or with a combination of n-3 and n-6 polyunsaturated fatty acids, on the extent of steatosis and collagen content in the liver.

RESULTS

Nodular cirrhosis, increased collagen content, and lipid accumulation were established after 4 months of treatment with thioacetamide. When the animals were fed a diet rich in oleic acid for 2 weeks, the steatosis and fibrosis decreased. Supplementation with n-3 polyunsaturated fatty acids favored reductions in collagen content but did not reduce the fat accumulation. With a diet supplemented with a mixture of n-3 and n-6 fatty acids we found no reduction in either lipid accumulation or collagen content.

CONCLUSIONS

Fibrosis and steatosis may be influenced by dietary fat, and monounsaturated fat appears to influence favorably the histologic recovery of the damaged liver.

Serum amino acid changes in rats with thioacetamide-induced liver cirrhosis

To date, no attempt has been made to study alterations occurring in the amino acid profile in chronic models of thioacetamide-induced liver cirrhosis. In this work, changes in serum amino acids and proteins in rats with thioacetamide-induced liver cirrhosis are reported, together with changes in enzyme activities in the liver and serum. Seventeen female Wistar rats were used. Eight rats were given 300 mg thioacetamide/l in drinking water for 4 months and nine rats were given water ad libitum during the same time-period. Significant increases in glycine, alanine, serine, methionine, glutamate, ornithine, phenylalanine, tyrosine, histidine and proline were observed in rats with the resulting experimental liver cirrhosis. Threonine, taurine, glutamine, lysine and citrulline tended to increase while isoleucine, leucine, aspartate, arginine and tryptophan tended to decrease. Total and nonessential amino acids increased significantly in cirrhotic animals. Total essential and aromatic amino acids tended to increase in the thioacetamide-treated group, whereas branched chain amino acids tended to decrease in the same group. Regarding serum proteins, a decrease in albumin concentration in the thioacetamide-treated animals was the only change detected. The liver enzyme activities under observation (aspartate and alanine aminotransferases, glutamate dehydrogenase and threonine deaminase) were lower in the thioacetamide group. Decreases were significant for both transaminases and threonine deaminase. Results for serum activities showed that transaminases did not change in thioacetamide-treated rats in comparison with controls. In contrast, alkaline phosphatase rose dramatically in cirrhotic rats. We conclude that the serum amino acid pattern in this chronic model of liver cirrhosis resembles in part that of the corresponding human disease.