Hepatic fibrogenesis and transforming growth factor/Smad signaling activation in rats chronically exposed to low doses of lead

Low concentrations of lead disturb phenotypical markers of the inflammatory and the anti-inflammatory profile of bone marrow-derived macrophages from BALB/c mice

Lead (Pb) is a ubiquitous toxic metal that decreases resistance to infections, in which the macrophages have an essential role. Pb adverse effects on nitric oxide (NO^-) production and variable effects on inflammatory cytokines in activated macrophages have been reported, but no effects have been reported in anti-inflammatory macrophages. We studied Pb (0.03-6 μg/dL equivalent to 0.014-2.89 μM) effects on the function of bone marrow-derived macrophages (BMDM) induced to either inflammatory or anti-inflammatory phenotypes, with LPS + IFNγ or IL-4+IL-13, respectively, and whether these effects are related. Pb did not induce cytotoxicity at any concentration in both macrophage phenotypes. In inflammatory BMDM, Pb (6 μg/dL) inhibited NO^- production without affecting inducible nitric oxide synthase (iNOS) levels or basal arginase activity. At 3 and 6 μg/dL, Pb enhanced the major histocompatibility complex class II (MHC II) membrane expression but did not modify CD86 expression, TNFα, or IL-1β production and secretion. In anti-inflammatory BMDM, Pb did not alter arginase activity, but at 3 and 6 μg/dL, increased TGF-β1 and mannose receptor expression. Results showed that environmentally relevant concentrations of Pb alter functional outcomes or phenotypic markers of anti-inflammatory for the first time. The Pb effects on the inflammatory macrophages are not dependent on negative feedback resulting from the Pb effect on the anti-inflammatory phenotype. The Pb affected only some molecules or specific pathways related to both phenotypes. These effects could be related to Pb effects on immune defense against intracellular pathogens and allergy susceptibility.

MicroRNA-326 attenuates hepatic stellate cell activation and liver fibrosis by inhibiting TLR4 signaling

Hepatic fibrosis is a chronic inflammatory and reversible repair reaction of the liver under the continuous action of virus or various injuries. In this study, we aimed at identifying the role of miR-326 in the hepatic stellate cell (HSC) activation and liver fibrosis and its potential mechanism. In this study, the liver fibrosis mouse model was developed by injecting CCl₄ . Liver tissue morphology was observed and the expression level of α-smooth muscle actin, collagen1α1 and miR-326 was measured. Target gene identification was performed by loss-of-function and gain-of-function. The effect of miR-326 on the expression level of the cytokines associated with the TLR4/MyD88/nuclear factor-κB (NF-κB) pathway was assessed in vitro and in vivo. We show that miR-326 was downregulated in CCl₄ -induced fibrotic mice and activated HSCs. The target gene of miR-326 is TLR4. Moreover, miR-326 inhibited the activation of HSCs in vitro through TLR4/MyD88/NF-κB signaling. miR-326 attenuated hepatic fibrosis and inflammation of CCl₄ -induced mice in vivo. Our results demonstrate for the first time that miR-326 inhibits HSC activation through TLR4/MyD88/NF-κB signaling. Furthermore, miR-326 plays critical roles in attenuating liver fibrosis and inflammation, suggesting the therapeutic potential of miRNAs.

Compression of morbidity in a progeroid mouse model through the attenuation of myostatin/activin signalling

BACKGROUND

One of the principles underpinning our understanding of ageing is that DNA damage induces a stress response that shifts cellular resources from growth towards maintenance. A contrasting and seemingly irreconcilable view is that prompting growth of, for example, skeletal muscle confers systemic benefit.

METHODS

To investigate the robustness of these axioms, we induced muscle growth in a murine progeroid model through the use of activin receptor IIB ligand trap that dampens myostatin/activin signalling. Progeric mice were then investigated for neurological and muscle function as well as cellular profiling of the muscle, kidney, liver, and bone.

RESULTS

We show that muscle of Ercc1^Δ/- progeroid mice undergoes severe wasting (decreases in hind limb muscle mass of 40-60% compared with normal mass), which is largely protected by attenuating myostatin/activin signalling using soluble activin receptor type IIB (sActRIIB) (increase of 30-62% compared with untreated progeric). sActRIIB-treated progeroid mice maintained muscle activity (distance travel per hour: 5.6 m in untreated mice vs. 13.7 m in treated) and increased specific force (19.3 mN/mg in untreated vs. 24.0 mN/mg in treated). sActRIIb treatment of progeroid mice also improved satellite cell function especially their ability to proliferate on their native substrate (2.5 cells per fibre in untreated progeroids vs. 5.4 in sActRIIB-treated progeroids after 72 h in culture). Besides direct protective effects on muscle, we show systemic improvements to other organs including the structure and function of the kidneys; there was a major decrease in the protein content in urine (albumin/creatinine of 4.9 sActRIIB treated vs. 15.7 in untreated), which is likely to be a result in the normalization of podocyte foot processes, which constitute the filtration apparatus (glomerular basement membrane thickness reduced from 224 to 177 nm following sActRIIB treatment). Treatment of the progeric mice with the activin ligand trap protected against the development of liver abnormalities including polyploidy (18.3% untreated vs. 8.1% treated) and osteoporosis (trabecular bone volume; 0.30 mm³ in treated progeroid mice vs. 0.14 mm³ in untreated mice, cortical bone volume; 0.30 mm³ in treated progeroid mice vs. 0.22 mm³ in untreated mice). The onset of neurological abnormalities was delayed (by ~5 weeks) and their severity reduced, overall sustaining health without affecting lifespan.

CONCLUSIONS

This study questions the notion that tissue growth and maintaining tissue function during ageing are incompatible mechanisms. It highlights the need for future investigations to assess the potential of therapies based on myostatin/activin blockade to compress morbidity and promote healthy ageing.

Therapeutic Effect of Glycyrrhizin Arginine Salt on Rat Cholestatic Cirrhosis and its Mechanism

To investigate the therapeutic effect of glycyrrhizin arginine salt on rat cholestatic cirrhosis, we subjected male Sprague Dawley rats to common bile duct ligation for 14 days and treated them with distilled water (model group), arginine, or a low or high dose of glycyrrhizin arginine salt by gavage. A sham-operated group was used as a control group. Treatment with glycyrrhizin arginine salt substantially improved animal growth rates, reduced the ratio of liver weight to body weight and decreased total bilirubin, aspartate aminotransferase, 8-isoprostane and malondialdehyde compared with the values measured in the model group. The progress of liver fibrosis, as detected by hematoxylin and eosin and Masson’s trichrome staining, was slower in the glycyrrhizin arginine salt groups than in the model group or the arginine group. Reductions of bile salt pool size, hepatic hydroxyproline content and fibrosis score were also seen in the glycyrrhizin arginine salt groups compared with the model group. Furthermore, glycyrrhizin arginine salt significantly reduced the expression of transforming growth factor [Formula: see text]1 (TGF-[Formula: see text]1), [Formula: see text]-smooth muscle actin, tumor necrosis factor-[Formula: see text] and matrix metalloproteinases 2 and 9. Glycyrrhizin arginine salt also inhibited the expression of [Formula: see text]-SMA and matrix metalloproteinases 2 and 9 in response to TGF-[Formula: see text]1 in LX-2 cells and primary rat hepatic stellate cells and mitigated the cytotoxicity induced by rat bile in HepG2 cells and primary rat hepatocytes.

Lentivirus-mediated over-expression of let-7b microRNA suppresses hepatic fibrosis in the mouse infected with Schistosoma japonicum

Transforming growth factor-β (TGF-β) signaling pathway is documented to participate in liver fibrosis via multifactorial mechanisms. microRNA Let-7b (Let-7b) has been proved to alleviate cell fibrosis through regulating TGF-β receptor I (TβRI), but whether it is involved in Schistosomiasis liver fibrosis (SLF) has not been determined. In the present, SLF mice model was used to investigate Let-7b's function and mechanism in SLF. We found that hepatic let-7b expression was continuously declined in SLF, accompanied by the induction of TGF-β pathway molecules (TGF-β1, TβRI), profibrogenic mediators (α-SMA, colla I), and Th1/Th2 cells response factors (IFN-γ, IL-4). When recombinant Lentivirus of let-7b (Lenti-let-7b) was transfected into S. japonicum-infected mice, the mice hepatic fibrosis was distinctly ameliorated, and TGF-β1, TβRI, α-SMA, and colla I expressions were remarkly decreased, mice serum IL-4 and IFN-γ levels were reduced. Similarly, over-expression of let-7b down-regulated the expression of TβRI in THP-1 cells transfected with let-7b mimics, while TβRI was up-regulated after treated with let-7b inhibitor. These findings suggested that let-7b is a negative regulator to SLF through downregulating TβRI, and inhibits Th1 and Th2 type cell immune response. This provides a novel potential therapeutic strategy for SFL prevention.

The Effects of Different Fluences of 1064 nm Q-Switched Nd:YAG Laser on Skin Repair and Skin Barrier Dysfunction in Mice

OBJECTIVE

The purpose of this study was to investigate the effects of different fluences of Q-switched 1064 nm Nd:YAG laser on skin repair and barrier, and clarify its mechanisms.

BACKGROUND DATA

The Q-switched 1064 nm Nd:YAG laser is widely used for rejuvenation, which needs appropriate fluence data to optimize efficacy and minimize side effects, and for elucidation of action mechanism.

MATERIALS AND METHODS

The dorsal skin of BABL/c mice was administered 0, 1, 1.5, and 2 J/cm2 energy level laser, twice a week for 4 weeks. Immediately, 7, 14, 21, and 28 days after last treatment, the skin elasticity, moisture content, and transepidermal water loss (TEWL) were measured; 7, 14, 21, and 28 days after last treatment, the hydroxyproline content, mRNA level of procollagen types I and III, protein level of keratin-10 (K-10), filaggrin, transforming growth factor beta receptor II (TGFβRII), Smad2, and p65 were detected.

RESULTS

Compared with the unirradiated control, the laser treatments decreased skin elasticity immediately, but increased skin moisture content in the 2 J/cm2 group, and then from day 21 to day 28, the skin elasticity, moisture content, hydroxyproline content, and gene expression of types I and III procollagen increased significantly. The TEWL value of the irradiated group significantly increased after irradiation immediately and 7 days after, K-10 and filaggrin were also decreased at 7 days after. The phosphorylation of TGFβRII (p-TGFβRII) increased at days 7 and 21, and phosphorylation of Smad2 (p-Smad2) was induced at 21 days.

CONCLUSIONS

Irradiation of 1064 nm Q-switched Nd:YAG laser was able to markedly promote repair of mouse skin within 28 days through stimulation of collagen synthesis, with less skin barrier dysfunction, especially at the 1.5 J/cm2 fluence, and the activation of TGFβ1-signaling pathways seemed to play an important role in repair.

Interventional effects of Plumbago zeylanica L. decoction on CCl4-induced hepatic fibrosis in rats

AIM: To investigate the intervention effects of Plumbago zeylanica L. decoction (PZL) on carbon tetrachloride (CCl4)-induced hepatic fibrosis in rats.

METHODS: A model of hepatic fibrosis was established by subcutaneous injection of 40% CCl₄ in rats. SD rats were randomly divided into five groups (10 rats in each group): a model group, a positive control group (colchicines 0.25 mg/kg), high-, medium- and low-dose PZL groups. A blank control group was also established. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were tested using a ultraviolet-visible pectrophotometer (UV). Serum levels of total bilirubin (TBIL), direct bilirubin (DBIL) and indirect bilirubin (IBIL) were detected by the method of vanadate oxidation. The contents of hyaluronic acid (HA), laminin (LN), procollagen type Ⅲ (P3NP), and type Ⅳ collagen (CⅣ) were detected by radioimmunoassay. HE staining was used to examine the degree of hepatic fibrosis, and the expression of collagen type Ⅰ and Ⅲ and α-SMA in hepatic tissues was detected by immunohistochemistry.

RESULTS: Compared with the model group, the levels of ALT, AST, TBIL, DBIL and IBIL were significantly decreased in the PZL groups. PZL could also significantly reduce the contents of HA, LN, P3NP, and CⅣ. HE staining showed that PZL could significantly reduce the degree of hepatic fibrosis. Immunohistochemistry showed that the expression of collagen type Ⅰ and Ⅲ and α-SMA in hepatic tissues was decreased by PZL (P < 0.05 or P < 0.01), and the effect was dose-dependent.

CONCLUSION: PZL has a protective effect against CCl₄-induced liver fibrosis in rats possibly by improving the liver function, inhibiting liver cell degeneration and necrosis, reducing secretion of collagen by hepatic stellate cells and promoting extracellular matrix degradation.