Hepatic stellate cells express thymosin Beta 4 in chronically damaged liver

Targeted Deletion of Thymosin Beta 4 in Hepatic Stellate Cells Ameliorates Liver Fibrosis in a Transgenic Mouse Model

Liver fibrosis is the most common feature of liver disease, and activated hepatic stellate cells (HSCs) are the main contributors to liver fibrosis. Thus, finding key targets that modulate HSC activation is important to prevent liver fibrosis. Previously, we showed that thymosin β4 (Tβ4) influenced HSC activation by interacting with the Hedgehog pathway in vitro. Herein, we generated Tβ4 conditional knockout (Tβ4-flox) mice to investigate in vivo functions of Tβ4 in liver fibrosis. To selectively delete Tβ4 in activated HSCs, double-transgenic (DTG) mice were generated by mating Tβ4-flox mice with α-smooth muscle actin (α-Sma)-Cre-ER^T2 mice, and these mice were administered carbon tetrachloride (CCl₄) or underwent bile duct ligation to induce liver fibrosis. Tβ4 was selectively suppressed in the activated HSCs of DTG mouse liver, and this reduction attenuated liver injury, including fibrosis, in both fibrotic models by repressing Hedgehog (Hh) signaling. In addition, the re-expression of Tβ4 by an adeno-associated virus reversed the effect of HSC-specific Tβ4 deletion and led to liver fibrosis with Hh activation in CCl₄-exposed mice treated with tamoxifen. In conclusion, our results demonstrate that Tβ4 is a crucial regulator of HSC activation, suggesting it as a novel therapeutic target for curing liver fibrosis.

Thymus transplantation regulates blood pressure and alleviates hypertension-associated heart and kidney damage via transcription factors FoxN1 pathway

Previous studies have found that thymus is involved in the process of hypertension. However, whether thymus transplantation alleviates target organ damage in hypertensive mice remains unknown. The aim of this study was to evaluate the effects of thymus transplantation on blood pressure and target organ changes in mice with hypertension. Mice were randomly divided into normal control group (Con), hypertensive group (HTN) and thymus transplantation group (HTN + Trans). Thymus of neonatal mice was transplanted into the renal capsule of the transplantation group. After transplantation, the mouse tail noninvasive pressure was measured and heart function was evaluated weekly. Then mice were euthanized and organs or tissues were harvested at 4 weeks post-transplantation. The blood pressure of HTN + Trans group was lower than that in the HTN group. The expression of FoxN1, Aire, ATRAP, thymosin β4 and the content of sjTREC in thymus of HTN group was decreased and the number of naïve T cells in HTN group was lower compared with other two groups. The ratio of cTEC/mTEC in HTN group was higher than that in Con group and lower than that in HTN + Trans group. Cardiac pathology showed cardiac hypertrophy and fibrosis in HTN group whereas thymus transplantation improved heart function and structure. Altogether, our findings demonstrated thymus transplantation could improve thymus function of hypertensive mice, which increased the expression of thymus transcription factor FoxN1, affected the proportion of T cell subsets, and increased thymosin β4 thereby reducing blood pressure and reversing the progression of target organ damage.

Thymosin Beta 4 Inhibits LPS and ATP-Induced Hepatic Stellate Cells via the Regulation of Multiple Signaling Pathways

Risk signals are characteristic of many common inflammatory diseases and can function to activate nucleotide-binding oligomerization (NLR) family pyrin domain-containing 3 (NLRP3), the innate immune signal receptor in cytoplasm. The NLRP3 inflammasome plays an important role in the development of liver fibrosis. Activated NLRP3 nucleates the assembly of inflammasomes, leading to the secretion of interleukin (IL)-1β and IL-18, the activation of caspase-1, and the initiation of the inflammatory process. Therefore, it is essential to inhibit the activation of the NLRP3 inflammasome, which plays a vital role in the immune response and in initiating inflammation. RAW 264.7 and LX-2 cells were primed with lipopolysaccharide (LPS) for 4 h and subsequently stimulated for 30 min with 5 mM of adenosine 5'-triphosphate (ATP) to activate the NLRP3 inflammasome. Thymosin beta 4 (Tβ4) was supplemented to RAW264.7 and LX-2 cells 30 min before ATP was added. As a result, we investigated the effects of Tβ4 on the NLRP3 inflammasome. Tβ4 prevented LPS-induced NLRP3 priming by inhibiting NF-kB and JNK/p38 MAPK expression and the LPS and ATP-induced production of reactive oxygen species. Moreover, Tβ4 induced autophagy by controlling autophagy markers (LC3A/B and p62) through the inhibition of the PI3K/AKT/mTOR pathway. LPS combined with ATP significantly increased thee protein expression of inflammatory mediators and NLRP3 inflammasome markers. These events were remarkably suppressed by Tβ4. In conclusion, Tβ4 attenuated NLRP3 inflammasomes by inhibiting NLRP3 inflammasome-related proteins (NLRP3, ASC, IL-1β, and caspase-1). Our results indicate that Tβ4 attenuated the NLRP3 inflammasome through multiple signaling pathway regulations in macrophage and hepatic stellate cells. Therefore, based on the above findings, it is hypothesized that Tβ4 could be a potential inflammatory therapeutic agent targeting the NLRP3 inflammasome in hepatic fibrosis regulation.

Comparative proteomic analysis of mustard lung as a complicated disease using systems biology approach

During Iraq-Iran conflict, chemical weapons, particularly SM gas, were used numerous times, whose aftereffects are still present. This study aimed to compare serum proteome in the chronic ML (n = 10) and HC (n = 10). TMT label-based quantitative proteomics was used to examine serums from two groups. Among total significant proteins, 14 proteins were upregulated (log₂ ≥ FC 0.5, p 0.05), and 6 proteins were downregulated (log₂ ≤ FC - 0.5, p 0.05). By helping PPI network, and EA, 11 main pathways connected to significantly different protein expression levels were discovered, including inflammatory and cell adhesion signaling pathways. It may be deduced that the wounded organs of exposed individuals experience poor repair cycles of cell degeneration and regeneration because certain repair signals were elevated while other structural and adhesion molecules were downregulated. The systems biology approach can help enhance our basic knowledge of biological processes, and contribute to a deeper understanding of pathophysiological mechanisms, as well as the identification of potential biomarkers of disease.

A novel monoacylglycerol lipase-targeted 18F-labeled probe for positron emission tomography imaging of brown adipose tissue in the energy network

Monoacylglycerol lipase (MAGL) constitutes a serine hydrolase that orchestrates endocannabinoid homeostasis and exerts its function by catalyzing the degradation of 2-arachidonoylglycerol (2-AG) to arachidonic acid (AA). As such, selective inhibition of MAGL represents a potential therapeutic and diagnostic approach to various pathologies including neurodegenerative disorders, metabolic diseases and cancers. Based on a unique 4-piperidinyl azetidine diamide scaffold, we developed a reversible and peripheral-specific radiofluorinated MAGL PET ligand [18F]FEPAD. Pharmacokinetics and binding studies on [18F]FEPAD revealed its outstanding specificity and selectivity towards MAGL in brown adipose tissue (BAT) - a tissue that is known to be metabolically active. We employed [18F]FEPAD in PET studies to assess the abundancy of MAGL in BAT deposits of mice and found a remarkable degree of specific tracer binding in the BAT, which was confirmed by post-mortem tissue analysis. Given the negative regulation of endocannabinoids on the metabolic BAT activity, our study supports the concept that dysregulation of MAGL is likely linked to metabolic disorders. Further, we now provide a suitable imaging tool that allows non-invasive assessment of MAGL in BAT deposits, thereby paving the way for detailed mechanistic studies on the role of BAT in endocannabinoid system (ECS)-related pathologies.

The Role of Tβ4-POP-Ac-SDKP Axis in Organ Fibrosis

Fibrosis is a pathological process in which parenchymal cells are necrotic and excess extracellular matrix (ECM) is accumulated due to dysregulation of tissue injury repair. Thymosin β4 (Tβ4) is a 43 amino acid multifunctional polypeptide that is involved in wound healing. Prolyl oligopeptidase (POP) is the main enzyme that hydrolyzes Tβ4 to produce its derivative N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) which is found to play a role in the regulation of fibrosis. Accumulating evidence suggests that the Tβ4-POP-Ac-SDKP axis widely exists in various tissues and organs including the liver, kidney, heart, and lung, and participates in the process of fibrogenesis. Herein, we aim to elucidate the role of Tβ4-POP-Ac-SDKP axis in hepatic fibrosis, renal fibrosis, cardiac fibrosis, and pulmonary fibrosis, as well as the underlying mechanisms. Based on this, we attempted to provide novel therapeutic strategies for the regulation of tissue damage repair and anti-fibrosis therapy. The Tβ4-POP-Ac-SDKP axis exerts protective effects against organ fibrosis. It is promising that appropriate dosing regimens that rely on this axis could serve as a new therapeutic strategy for alleviating organ fibrosis in the early and late stages.

Glycogen synthase kinase-3β: a promising candidate in the fight against fibrosis

Fibrosis exists in almost all organs/tissues of the human body, plays an important role in the occurrence and development of diseases and is also a hallmark of the aging process. However, there is no effective prevention or therapeutic method for fibrogenesis. As a serine/threonine (Ser/Thr)-protein kinase, glycogen synthase kinase-3β (GSK-3β) is a vital signaling mediator that participates in a variety of biological events and can inhibit extracellular matrix (ECM) accumulation and the epithelial-mesenchymal transition (EMT) process, thereby exerting its protective role against the fibrosis of various organs/tissues, including the heart, lung, liver, and kidney. Moreover, we further present the upstream regulators and downstream effectors of the GSK-3β pathway during fibrosis and comprehensively summarize the roles of GSK-3β in the regulation of fibrosis and provide several potential targets for research. Collectively, the information reviewed here highlights recent advances vital for experimental research and clinical development, illuminating the possibility of GSK-3β as a novel therapeutic target for the management of tissue fibrosis in the future.

Thymosin β4 inhibits PDGF-BB induced activation, proliferation, and migration of human hepatic stellate cells via its actin-binding domain

OBJECTIVES

Hepatic stellate cells (HSC) trans-differentiation is central to the development of liver fibrosis, marked by the expression of pro-fibrogenic genes and the proliferation and migration of activated HSC. Therefore, preventing and/or reverting the activation, proliferation, and migration of HSC may lead to new therapies for treating fibrosis/cirrhosis. Thymosin β4 (Tβ4) inhibits PDGF-BB-induced fibrogenesis, proliferation and migration of HSC by blocking Akt phosphorylation. Here, we utilized Tβ4-derived peptides: amino-terminal-Ac-SDKPDMAEIEKFDKS (1-15aa) and actin-binding-LKKTETQ (17-23aa) to investigate the molecular mechanisms in the anti-fibrogenic actions of Tβ4.

METHODS

We used RT-PCR, Western blot, and proliferation and migration assays in early passages of human HSC cultures treated with PDGF-BB and/or Tβ4 peptides.

RESULTS

We showed that 17-23aa but not 1-15aa inhibited PDGF-BB-dependent up-regulation of PDGFβ receptor, α-SMA, and collagen 1. It also blunted the phosphorylation of Akt at T 308 and S473, resulting in the inhibition of phosphorylation of PRAS40, and HSC proliferation and migration. Interestingly, 1-15aa blocked Akt phosphorylation at S473, but not T308 by inhibiting mTOR phosphorylation, thus, it did not have any effect on HSC proliferation and migration.

CONCLUSION

These findings suggest that while 1-15aa has a minor effect on Akt phosphorylation, the anti-fibrogenic actions of Tβ4 are exerted via 17-23aa.

Thymosin β4 Prevents Oxidative Stress, Inflammation, and Fibrosis in Ethanol- and LPS-Induced Liver Injury in Mice

Thymosin beta 4 (Tβ4), an actin-sequestering protein, is involved in tissue development and regeneration. It prevents inflammation and fibrosis in several tissues. We investigated the role of Tβ4 in chronic ethanol- and acute lipopolysaccharide- (LPS-) induced mouse liver injury. C57BL/6 mice were fed 5% ethanol in liquid diet for 4 weeks plus binge ethanol (5 g/kg, gavage) with or without LPS (2 mg/kg, intraperitoneal) for 6 hours. Tβ4 (1 mg/kg, intraperitoneal) was administered for 1 week. We demonstrated that Tβ4 prevented ethanol- and LPS-mediated increase in liver injury markers as well as changes in liver pathology. It also prevented ethanol- and LPS-mediated increase in oxidative stress by decreasing ROS and lipid peroxidation and increasing the antioxidants, reduced glutathione and manganese-dependent superoxide dismutase. It also prevented the activation of nuclear factor kappa B by blocking the phosphorylation of the inhibitory protein, IκB, thereby prevented proinflammatory cytokine production. Moreover, Tβ4 prevented fibrogenesis by suppressing the epigenetic repressor, methyl-CpG-binding protein 2, that coordinately reversed the expression of peroxisome proliferator-activated receptor-γ and downregulated fibrogenic genes, platelet-derived growth factor-β receptor, α-smooth muscle actin, collagen 1, and fibronectin, resulting in reduced fibrosis. Our data suggest that Tβ4 has antioxidant, anti-inflammatory, and antifibrotic potential during alcoholic liver injury.

Mechanisms in hypertension and target organ damage: Is the role of the thymus key? (Review)

A variety of cells and cytokines have been shown to be involved in the whole process of hypertension. Data from experimental and clinical studies on hypertension have confirmed the key roles of immune cells and inflammation in the process. Dysfunction of the thymus, which modulates the development and maturation of lymphocytes, has been shown to be associated with the severity of hypertension. Furthermore, gradual atrophy, functional decline or loss of the thymus has been revealed to be associated with aging. The restoration or enhancement of thymus function via upregulation in the expression of thymus transcription factors forkhead box N1 or thymus transplantation may provide an option to halt or reverse the pathological process of hypertension. Therefore, the thymus may be key in hypertension and associated target organ damage, and may provide a novel treatment strategy for the clinical management of patients with hypertension in addition to different commercial drugs. The purpose of this review is to summarize and discuss the advances in our understanding of the impact of thymus function on hypertension from data from animal and human studies, and the potential mechanisms.

MALDI MS imaging investigation of the host response to visceral leishmaniasis

Mass spectrometry imaging (MSI) of animal tissues has become an important tool for in situ molecular analyses and biomarker studies in several clinical areas, but there are few applications in parasitological studies. Leishmaniasis is a neglected tropical disease, and experimental mouse models have been essential to evaluate pathological and immunological processes and to develop diagnostic methods. Herein we have employed MALDI MSI to examine peptides and low molecular weight proteins (2 to 20 kDa) differentially expressed in the liver during visceral leishmaniasis in mice models. We analyzed liver sections of Balb/c mice infected with Leishmania infantum using the SCiLS Lab software for statistical analysis, which facilitated data interpretation and thus highlighted several key proteins and/or peptides. We proposed a decision tree classification for visceral leishmaniasis with distinct phases of the disease, which are named here as healthy, acute infection and chronic infection. Among others, the ion of m/z 4963 was the most important to identify acute infection and was tentatively identified as Thymosin β4. This peptide was previously established as a recovery factor in the human liver and might participate in the response of mice to Leishmania infection. This preliminary investigation shows the potential of MALDI MSI to complement classical compound selective imaging techniques and to explore new features not yet recognized by these approaches.

Inhibition of acetaminophen-induced hepatotoxicity in mice by exogenous thymosinβ4 treatment

OBJECTIVE

To study the effects of exogenous thymosinβ4 (Tβ4) treatment in acetaminophen (APAP)-induced hepatotoxicity.

METHODS

Liver injury was induced in mice by a single intraperitoneal injection of APAP (500 mg/kg). Exogenous Tβ4 was intraperitoneally administrated at 0 h, 2 h and 4 h after APAP injection. Chloroquine (CQ) (60 mg/kg) was intraperitoneally injected 2 h before APAP administration to inhibit autophagy. Six hours after APAP injection liver injury was evaluated by histological examinations, biochemical measurements and enzyme linked immunosorbent assay (ELISAs). Western blots were performed to detect proteins expression.

RESULTS

Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly increased 6 h after APAP administration, but were significantly reduced by co-administration of Tβ4. Histological examinations demonstrated that Tβ4 reduced necrosis and inflammation induced by APAP. Immunofluorescence showed that Tβ4 suppressed APAP-induced translocation of high mobility group box-1 protein (HMGB1) from the nucleus to cytosol and intercellular space. Hepatic glutathione (GSH) depletion, malondialdehyde (MDA) formation and decreased superoxide dismutase (SOD) activities induced by APAP were all attenuated by Tβ4. APAP-induced increases in hepatic nuclear factor-κB (NF-κB) p65 protein expression and inflammatory cytokines production including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were reduced by Tβ4 treatment. Increased LC3 and p62 proteins in the liver tissues of APAP-treated mice were decreased by Tβ4 treatment, which indicated the enhancement of autophagy flux by Tβ4. Furthermore, inhibiting autophagy by CQ abrogated the protective effects of Tβ4 against APAP hepatotoxicity.

CONCLUSION

Exogenous Tβ4 treatment exerts protective effects against APAP-induced hepatotoxicity in mice. The underneath molecular mechanisms may involve autophagy enhancement and inhibition of oxidative stress by Tβ4.

Thymosin β4 alleviates renal fibrosis and tubular cell apoptosis through TGF-β pathway inhibition in UUO rat models

BACKGROUND

Thymosin β4 (Tβ4) is closely associated with the cytoskeleton, inflammation, wound healing, angiogenesis, apoptosis, and myocardial regeneration, but the effects of Tβ4 treatment on chronic renal tubular interstitial fibrosis (CRTIF) are poorly known. This study aimed to examine the effects of Tβ4 on the renal apoptosis and the expression of transforming growth factor (TGF-β), E-cadherin, and α-smooth muscle actin (α-SMA) in CRTIF rat models.

METHODS

Male SD rats were randomized into four groups (sham group, unilateral ureteral obstruction (UUO) group, UUO + low-dose Tβ4 group, and UUO + high-dose Tβ4 group). The pathological changes of kidney tissue and its function were assessed two weeks after UUO. In renal interstitial tissue,TGF-β, E-cadherin and α-SMA expression was detected by western blot. In tubular epithelial cells, E-cadherin and α-SMA expression was detected using Real-time qPCR and western blot. Cell apoptosis of rat renal interstitial tissue and tubular epithelial cells was evaluated by immunofluorescence and western blot.

RESULTS

Two weeks after UUO, no differences in blood urea nitrogen and creatinine were observed between the four groups (P > 0.05). Compared to the UUO group, Tβ4 treatment decreased the 24-h proteinuria (P < 0.001) and reduced the area of pathological change (P < 0.01); this effect was more apparent in the UUO + high-dose Tβ4 group. Compared to the UUO group, a significant decrease in TGF-β and α-SMA protein expression was observed in the high-dose Tβ4 group. The level of E-cadherin protein was lower in the UUO group than the Tβ4 groups, and high-dose Tβ4 treatment further increased E-cadherin expression and improved cell apoptosis in the renal interstitial tissue. Analysis of in vitro tubular epithelial cells showed that α-SMA mRNA and protein expression decreased, while E-cadherin mRNA and protein expression increased by Tβ4 treatment. Similarly, these changes were more significant in the UUO + high-dose Tβ4 group. Tβ4 treatment improved the apoptosis of In vitro tubular epithelial cells compared with pure TGF-β stimulation, and equally, the decrease of apoptosis was more apparent in the TGF-β + high-dose Tβ4 group.

CONCLUSIONS

Tβ4 treatment might alleviate the renal fibrosis and apoptosis of tubular epithelial cells through TGF-β pathway inhibition in UUO rats with CRTIF.

Effects of exogenous thymosin β4 on carbon tetrachloride-induced liver injury and fibrosis

The present study investigated the effects of exogenous thymosin β4 (TB4) on carbon tetrachloride (CCl₄)-induced acute liver injury and fibrosis in rodent animals. Results showed that both in mice and rats CCl₄ rendered significant increases in serum alanine aminotransferase and aspartate aminotransferase, hepatic malondialdehyde formation, decreases in antioxidants including superoxide dismutase and glutathione, and up-regulated expressions of transforming growth factor-β1, α-smooth muscle actin, tumor necrosis factor-α and interleukin-1β in the liver tissues. Hydroxyproline contents in the rat livers were increased by CCl₄. Histopathological examinations indicated that CCl₄ induced extensive necrosis in mice livers and pseudo-lobule formations, collagen deposition in rats livers. However, all these changes in mice and rats were significantly attenuated by exogenous TB4 treatment. Furthermore, up-regulations of nuclear factor-κB p65 protein expression by CCl₄ treatment in mice and rats livers were also remarkably reduced by exogenous TB4 administration. Taken together, findings in this study suggested that exogenous TB4 might prevent CCl₄-induced acute liver injury and subsequent fibrosis through alleviating oxidative stress and inflammation.

Thymosin-β4 inhibits proliferation and induces apoptosis of hepatic stellate cells through PI3K/AKT pathway

Liver fibrosis is a necessary stage for chronic liver diseases, and serious threat to human health. Hepatic fibrosis is a necessary stage for chronic liver diseases. Hepatic stellate cells (HSCs) are the primary cell type responsible for fibrosis. Thymosin beta 4 (Tβ4) has a potential role in the pathogenesis of liver fibrosis and that it is especially associated with the activation of HSCs, however, the underlying mechanisms are not fully elucidated. Herein, we investigated the potential role of Tβ4 in liver fibrosis by describing the effects of Tβ4, and we discuss the possible signaling pathway regulated by Tβ4. The expression of Tβ4 was significantly decreased in human HSC cell line LX-2 and CCl4-treated mouse liver. The depletion of Tβ4 significantly associated with the activation of HSCs via the enhanced expression of α-SMA and vimentin. Tβ4 significantly suppressed the viability and migration of HSCs. Understanding the potential effects and regulatory mechanism of Tβ4 in liver fibrosis might help to provide a novel treatment for patients with liver fibrosis.

Thymosin beta-4 regulates activation of hepatic stellate cells via hedgehog signaling

The molecular mechanisms of thymosin beta-4 (TB4) involved in regulating hepatic stellate cell (HSC) functions remain unclear. Therefore, we hypothesize that TB4 influences HSC activation through hedgehog (Hh) pathway. HSC functions declined in a TB4 siRNA-treated LX-2. TB4 suppression down-regulated both integrin linked kinase (ILK), an activator of smoothened, and phosphorylated glycogen synthase kinase 3 beta (pGSK-3B), an inactive form of GSK-3B degrading glioblastoma 2 (GLI2), followed by the decreased expression of both smoothened and GLI2. A TB4 CRISPR also blocked the activation of primary HSCs, with decreased expression of smoothened, GLI2 and ILK compared with cells transfected with nontargeting control CRISPR. Double immunostaining and an immunoprecipitation assay revealed that TB4 interacted with either smoothened at the cytoplasm or GLI2 at the nucleus in LX-2. Smoothened suppression in primary HSCs using a Hh antagonist or adenovirus transduction decreased TB4 expression with the reduced activation of HSCs. Tb4-overexpressing transgenic mice treated with CCl₄ were susceptible to the development hepatic fibrosis with higher levels of ILK, pGSK3b, and Hh activity, as compared with wild-type mice. These findings demonstrate that TB4 regulates HSC activation by influencing the activity of Smoothened and GLI2, suggesting TB4 as a novel therapeutic target in liver disease.

miR-200c Accelerates Hepatic Stellate Cell-Induced Liver Fibrosis via Targeting the FOG2/PI3K Pathway

BACKGROUND

Although expression of miR-200s is aberrant in liver fibrosis, its role in liver fibrogenesis still remains unknown. Here, we investigated the role of miR-200c in the activation of human hepatic stellate cells (HSCs) and induction of liver fibrosis.

METHODS

We engineered human HSCs (LX2 cell line) to stably express miR-200c (LX2-200c) or empty vector control (LX2-nc).

RESULTS

miR-200c expression upregulated α-smooth muscle actin (SMA) and vimentin, enhanced HSCs growth and migration, increased expression of collagen type I (a main component of ECM) gene and secretion of epidermal growth factor (EGF), and upregulated the phosphorylation of Akt, a downstream effector of the PI3K pathway. As a target of miR-200s and inhibitor of PI3K pathway, FOG2 protein expression was significantly suppressed in LX2-200c cells. Moreover, LY294002, a highly selective inhibitor of PI3K, blocked phosphorylation of Akt and the effects of miR-200c.

CONCLUSIONS

These data suggest that miR-200c activates HSCs in liver fibrosis possibly by downregulating FOG2 protein expression and upregulating PI3K/Akt signaling. Autocrine activation of EGF signaling may also be a mechanism of miR-200c-mediated HSCs activation. So miR-200c can be a potential marker for HSCs activation and liver fibrosis progression, as well as a potential target to attenuate liver fibrosis.

Thymosin β4 inhibits microglia activation through microRNA 146a in neonatal rats following hypoxia injury

Neuroinflammation mediated by activated microglia plays a pivotal role in the pathogenesis of neurological disorders, including hypoxic injury of the developing brain. Thymosin β4 (Tβ4), the major G-actin-sequestering molecule, has an anti-inflammatory effect and has been used to treat various neurological diseases. However, the effect of Tβ4 on hypoxia-induced microglia activation in the developing brain remains unclear. We investigate here the effect of Tβ4 on microglia activation of neonatal rats after hypoxia exposure. Tβ4 treatment was carried out on 1-day-old rats and BV-2 cells. Tβ4 expression in microglia was determined by quantitative real time-PCR, western blotting, and immunofluorescence staining. Secretion of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and nitric oxide (NO) was assessed by enzyme-linked immunosorbent assay and colorimetric assay. mRNA expression of TNF-α and IL-1β, and microRNA 146a expression was determined by quantitative real time-PCR. We showed that Tβ4 treatment significantly inhibited secretion of inflammatory mediators in the cerebellum of neonatal rats following hypoxia injury. Increased expression of endogenous Tβ4 in microglia was observed both in hypoxic rats and in BV-2 cells. Tβ4 treatment significantly inhibited the expression and secretion of hypoxia-induced TNF-α, IL-1β, and NO. Remarkably, microRNA 146a expression was found to have increased in Tβ4-treated BV-2 cells. We demonstrated the anti-inflammatory effect of Tβ4 in neonatal rats following hypoxic brain injury. More importantly, our data reveal, for the first time, that Tβ4 inhibits microglia activation in vitro. Therefore, this study contributes to understanding the role and mechanism of Tβ4 function in central nervous system diseases.

MicroRNA Expression Profiling in CCl₄-Induced Liver Fibrosis of Mus musculus

Liver fibrosis is a major pathological feature of chronic liver diseases, including liver cancer. MicroRNAs (miRNAs), small noncoding RNAs, regulate gene expression posttranscriptionally and play important roles in various kinds of diseases; however, miRNA-associated hepatic fibrogenesis and its acting mechanisms are poorly investigated. Therefore, we performed an miRNA microarray in the fibrotic livers of Mus musculus treated with carbon-tetrachloride (CCl₄) and analyzed the biological functions engaged by the target genes of differentially-expressed miRNAs through gene ontology (GO) and in-depth pathway enrichment analysis. Herein, we found that four miRNAs were upregulated and four miRNAs were downregulated more than two-fold in CCl₄-treated livers compared to a control liver. Eight miRNAs were predicted to target a total of 4079 genes. GO analysis revealed that those target genes were located in various cellular compartments, including cytoplasm, nucleolus and cell surface, and they were involved in protein-protein or protein-DNA bindings, which influence the signal transductions and gene transcription. Furthermore, pathway enrichment analysis demonstrated that the 72 subspecialized signaling pathways were associated with CCl₄-induced liver fibrosis and were mostly classified into metabolic function-related pathways. These results suggest that CCl₄ induces liver fibrosis by disrupting the metabolic pathways. In conclusion, we presented several miRNAs and their biological processes that might be important in the progression of liver fibrosis; these findings help increase the understanding of liver fibrogenesis and provide novel ideas for further studies of the role of miRNAs in liver fibrosis.

Thymosin Beta 4 Is a Potential Regulator of Hepatic Stellate Cells

Liver fibrosis, a major characteristic of chronic liver disease, is inappropriate tissue remodeling caused by prolonged parenchymal cell injury and inflammation. During liver injury, hepatic stellate cells (HSCs) undergo transdifferentiation from quiescent HSCs into activated HSCs, which promote the deposition of extracellular matrix proteins, leading to liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is the most abundant member of the highly conserved β-thymosin family and controls cell morphogenesis and motility by regulating the dynamics of the actin cytoskeleton. Tβ4 is known to be involved in various cellular responses, including antiinflammation, wound healing, angiogenesis, and cancer progression. Emerging evidence suggests that Tβ4 is expressed in the liver; however, its biological roles are poorly understood. Herein, we introduce liver fibrogenesis and recent findings regarding the function of Tβ4 in various tissues and discuss the potential role of Tβ4 in liver fibrosis with a special focus on the effects of exogenous and endogenous Tβ4. Recent studies have revealed that activated HSCs express Tβ4 in vivo and in vitro. Treatment with the exogenous Tβ4 peptide inhibits the proliferation and migration of activated HSCs and reduces liver fibrosis, indicating it has an antifibrotic action. Meanwhile, the endogenously expressed Tβ4 in activated HSCs is shown to promote HSCs activation. Although the role of Tβ4 has not been elucidated, it is apparent that Tβ4 is associated with HSC activation. Therefore, understanding the potential roles and regulatory mechanisms of Tβ4 in liver fibrosis may provide a novel treatment for patients.

Potential role of thymosin Beta 4 in liver fibrosis

Liver fibrosis, the main characteristic of chronic liver diseases, is strongly associated with the activation of hepatic stellate cells (HSCs), which are responsible for extracellular matrix production. As such, investigating the effective regulators controlling HSC activation provides important clues for developing therapeutics to inhibit liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is known to be involved in various cellular responses. A growing body of evidence suggests that Tβ4 has a potential role in the pathogenesis of liver fibrosis and that it is especially associated with the activation of HSCs. However, it remains unclear whether Tβ4 promotes or suppresses the activation of HSCs. Herein, we review the potential role of Tβ4 in liver fibrosis by describing the effects of exogenous and endogenous Tβ4, and we discuss the possible signaling pathway regulated by Tβ4. Exogenous Tβ4 reduces liver fibrosis by inhibiting the proliferation and migration of HSCs. Tβ4 is expressed endogenously in the activated HSCs, but this endogenous Tβ4 displays opposite effects in HSC activation, either as an activator or an inhibitor. Although the role of Tβ4 has not been established, it is apparent that Tβ4 influences HSC activation, suggesting that Tβ4 is a potential therapeutic target for treating liver diseases.