Although hepatic stellate cells, which are liver specific pericytes, have been recognized within the vasculature of the sinusoid for more than one hundred years, the biology and function of these cells is unclear. Recent studies have highlighted the key role of stellate cells in a number of fundamental processes that include wound healing/fibrosis, vasoregulation, and vascular remodeling/angiogenesis. In the liver, these processes are particularly important in the development of cirrhosis, portal hypertension and cancer. This article highlights the recent advances in our understanding of the biology of hepatic stellate cells and discusses some of the recently-ascribed functions that are relevant to liver fibrosis, portal hypertension and cancer angiogenesis.
Cell Communication/physiology ; Humans ; Hypertension, Portal/*etiology ; Kupffer Cells/*physiology ; Liver Cirrhosis/*etiology ; Liver Neoplasms/blood supply/*etiology ; Neovascularization, Pathologic/etiology ; Pericytes/*physiology

OBJECTIVESTo investigate the relationship between the apoptosis of sinusoidal endothelial cells (SEC) and the hepatocyte injury of the livers after their transplantation into rats.

METHODSMale SD rats were divided into three groups randomly: sham group, UW1h group and UW12 h group. Orthotopic liver transplantations were performed using the technique described by Kamada with a modification. A survival rate curve was made using the Kaplan-Meier method. Liver tissue specimens and blood samples were collected at different time points after the surgeries. Six animals were sacrificed at each time-point. The liver injury was evaluated by serum ALT and HA levels. The incidence of apoptosis in SECs was measured using the Tunel method. Additionally, the typical morphology indication of apoptosis was observed by transmission electron microscopy.

RESULTSThe survival rate at 168 h in the UW12 h group was significantly lower than that in the UW1h group (F = 6.39, P<0.05). The levels of serum ALT and HA were significantly higher in UW12 h group than those in UW1h group (F = 3.99, P<0.05; F = 12.43, P<0.05). The serum ALT level reached its peak at 6 h after transplantation in both groups. The AI of SEC was significantly higher in the UW12 h group than those in the UW1h group and sham group (F = 63.58, P<0.01; F = 86.58, P<0.01). The apoptosis index (AI) in the UW1h group and in the UW12 h group both reached their peak at 6 h postoperatively and the AI of SEC of each group was positively correlated with their serum ALT levels significantly (r = 1.0, P,0.01; r = 0.962, P<0.05).

CONCLUSIONThe increase of apoptosis of SEC is significantly correlated with the dysfunction of the livers after transplantation in rats, and the dysfunction was mainly caused by the process of cold preservation/reperfusion injury.

Animals ; Apoptosis ; physiology ; Cryopreservation ; Endothelial Cells ; pathology ; Hepatocytes ; pathology ; Kupffer Cells ; pathology ; Liver ; pathology ; Liver Transplantation ; adverse effects ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; pathology

OBJECTIVETo explore the inhibitory effects on the activation of endotoxin-induced Kupffer cells (KCs) through short hairpin RNA (shRNA) targeting interleukin-1 receptor associated kinase-4 (IRAK-4) gene.

METHODSTwo effective transfection shRNA plasmid (pSIIRAK-4-A, pSIIRAK-4-B) and one invalidated plasmids (pSIIRAK-4-C) targeting IRAK-4 gene were constructed. The isolated mouse KCs were divided into three groups: the normal control group, the RNAi control group (pSIIRAK-4-C) and the RNAi effective group (pSIIRAK-4-A, pSIIRAK-4-B). Then KCs were stimulated with 0.1 microg/ml lipopolysaccharide (LPS) after 24 h transfection with the constructed plasmid. The expression of IRAK-4 gene and protein level were determined by RT-PCR and Western blot at 6 h after LPS stimulation, and the activities of NF-kappaB in KCs and the TNFalpha level were estimated by ELISA at 0 h, 1 h, 3 h, 6 h and 12 h.

RESULTSThe level of IRAK-4, the activities of NF-kappaB and the TNF-alpha level in the RNAi effective group were evidently lower than those in normal and RNAi control groups (P < 0.01) at 1 h, 3 h, and 6 h. Especially, the pSIIRAK-4-A group in which the changes of the above indices were of no difference (P > 0.05), had better inhibited effects than that of the pSIIRAK-4-B group (P < 0.01).

CONCLUSIONThe shRNA targeting IRAK-4 gene could effectively inhibit the activation of endotoxin-induced KCs.

Animals ; Endotoxins ; Interleukin-1 Receptor-Associated Kinases ; genetics ; metabolism ; Kupffer Cells ; metabolism ; Male ; Mice ; Mice, Inbred BALB C ; RNA Interference ; RNA, Small Interfering ; genetics ; Signal Transduction ; physiology

Hepatic fibrosis results from iterative hepatic injury with sustained inflammation, formation of scar tissue, loss of tissue architecture and organ failure. There is no doubt, from both human and animal studies, that too much or too protracted inflammation in the liver leads to excess scarring. During liver injury, Kupffer cells can quickly flood the hepatic milieu with soluble mediators, including oxidants, cytokines, and proteinases, which can affect stellate cell proliferation, migration, and differentiation. On the other hand, the contribution of Kupffer cells to regression of hepatic fibrosis has been demonstrated. These findings underscore the potential importance of hepatic macrophages in regulating both stellate cell biology and extracellular material degradation during regression of hepatic fibrosis. Therefore, biological characterization of Kupffer cells, their interactions with stellate cells in the cytokine environment are essential to understand the mechanisms underlying the progressive development of excessive scarring in the liver as well as the ability of the liver for tissue repair and recovery.
Animals ; Apoptosis ; Hepatic Stellate Cells ; physiology ; secretion ; Hepatocytes ; pathology ; Humans ; Kupffer Cells ; physiology ; secretion ; Liver Cirrhosis ; etiology ; metabolism ; pathology ; Liver Regeneration ; physiology ; Matrix Metalloproteinases, Secreted ; metabolism ; Transforming Growth Factor beta ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

BACKGROUND AND OBJECTIVE: Acute liver failure (ALF) is a type of disease with high mortality and rapid progression with no specific treatment methods currently available. Glucocorticoids exert beneficial clinical effects on therapy for ALF. However, the mechanism of this effect remains unclear and when to use glucocorticoids in patients with ALF is difficult to determine. The purpose of this study was to investigate the specific immunological mechanism of dexamethasone (Dex) on treatment of ALF induced by lipopolysaccharide (LPS)/D-galactosamine (D-GaIN) in mice. METHODS: Male C57BL/6 mice were given LPS and D-GaIN by intraperitoneal injection to establish an animal model of ALF. Dex was administrated to these mice and its therapeutic effect was observed. Hematoxylin and eosin (H&E) staining was used to determine liver pathology. Multicolor flow cytometry, cytometric bead array (CBA) method, and next-generation sequencing were performed to detect changes of messenger RNA (mRNA) in immune cells, cytokines, and Kupffer cells, respectively. RESULTS: A mouse model of ALF can be constructed successfully using LPS/D-GaIN, which causes a cytokine storm in early disease progression. Innate immune cells change markedly with progression of liver failure. Earlier use of Dex, at 0 h rather than 1 h, could significantly improve the progression of ALF induced by LPS/D-GaIN in mice. Numbers of innate immune cells, especially Kupffer cells and neutrophils, increased significantly in the Dex-treated group. In vivo experiments indicated that the therapeutic effect of Dex is exerted mainly via the glucocorticoid receptor (Gr). Sequencing of Kupffer cells revealed that Dex could increase mRNA transcription level of nuclear receptor subfamily 4 group A member 1 (Nr4a1), and that this effect disappeared after Gr inhibition. CONCLUSIONS In LPS/D-GaIN-induced ALF mice, early administration of Dex improved ALF by increasing the numbers of innate immune cells, especially Kupffer cells and neutrophils. Gr-dependent Nr4a1 upregulation in Kupffer cells may be an important ALF effect regulated by Dex in this process.
Animals ; Dexamethasone/therapeutic use* ; Disease Models, Animal ; Kupffer Cells/physiology* ; Liver Failure, Acute/pathology* ; Male ; Mice ; Mice, Inbred C57BL ; Nuclear Receptor Subfamily 4, Group A, Member 1/physiology* ; Receptors, Glucocorticoid/physiology*

Animals ; Colonic Neoplasms ; pathology ; Disease Models, Animal ; Humans ; Kupffer Cells ; cytology ; metabolism ; physiology ; Liver Neoplasms ; prevention & control ; secondary ; Mice ; Mice, Nude ; Neoplasm Metastasis ; Phagocytosis ; physiology ; Reactive Oxygen Species ; metabolism ; Splenectomy ; methods

OBJECTIVETo explore the possible mechanism of the inhibitory effect of liver X receptor alpha (LXRalpha) on lipopolysaccharide (LPS)-induced inflammation in mouse Kupffer cells (KCs).

METHODSThe KCs isolated from the liver of male KM mice and cultured in RPMI 1640 containing 20% FBS for 24 h were divided into control, LPS, T0901317, and LPS+T0901317 groups with corresponding treatments. The expressions of LXRalpha, interferon regulatory factor 3 (IRF3) and glucocorticoid receptor interacting protein 1 (GRIP1) in the KCs were detected by Western blotting. The levels of interferon beta (IFNbeta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the supernatant were detected by enzyme-linked immunosorbent assay (ELISA).

RESULTSThe level of LXRalpha protein was highest in T0901317 group and lowest in LPS group, and was significantly higher in LPS+T0901317 group than in LPS group but lower than in T0901317 group (P<0.05). The levels of IRF3 and GRIP1 protein were the highest in LPS group, and significantly lowered by T0901317 treatment (P<0.05). The expression of IRF3 and GRIP1 proteins in LPS group and LPS+ T0901317 group were significantly higher than those in the control and T0901317 groups (P<0.05). The concentration of IFN-beta was significantly higher in LPS group than in the control and T0901317 group (P<0.05), and decreased in LPS+T0901317 group in comparison with that in LPS group (P<0.05). IFN-beta was the lowest in T0901317 group. The levels of TNF-alpha and IL-1beta were the highest in LPS group (P<0.05), and comparable between the other 3 groups (P>0.05).

CONCLUSIONPre-treatment with T0901317 before LPS stimulation can suppress the expressions of IRF3 and GRIP1 to inhibit the inflammation and hence Kupffer cell activation.

Animals ; Cells, Cultured ; Hydrocarbons, Fluorinated ; pharmacology ; Inflammation ; chemically induced ; Interferon Regulatory Factor-3 ; metabolism ; Kupffer Cells ; cytology ; metabolism ; Lipopolysaccharides ; pharmacology ; Liver X Receptors ; Male ; Mice ; Nuclear Receptor Coactivator 2 ; metabolism ; Orphan Nuclear Receptors ; physiology ; Sulfonamides ; pharmacology

OBJECTIVETo investigate the role of p38 mitogen-activated protein kinase (MAPK) signal transduction pathway in the Kupffer cells production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in severely burns rats.

METHODSMale health adult Sprague-Dawley rats were randomized into four groups: sham burn rats given vehicle, sham burn rats given the p38 MAP kinase inhibitor SB203580, rats given a 30% total body surface area (TBSA) full-thickness burn and fluid resuscitation plus vehicle, and burn rats given injury and fluid resuscitation plus SB203580. Rats from each group were killed at 24 h after burn or sham burn and Kupffer cells (KCs) were isolated. After 18 h incubation, KCs next were stimulated with 50 ng/ml of LPS for 18 h. After stimulation, supernatants were removed for analysis of TNF-alpha and IL-1beta levels by ELISA. The TNF-alpha and IL-1beta mRNA expressions (by quantitative real-time RT-PCR) and the activities of p38 MAPK and JNK (by Western blot analysis) in KCs were examined.

RESULTSEighteen hours after 50 ng/ml LPS stimulation, KCs from burn rats released significantly higher levels of TNF-alpha and IL-1beta than did shams. The mRNA levels of TNF-alpha and IL-1beta in KCs increased significantly postburn. Western blot analysis suggested that expression of phosphorylated p38 MAPK and JNK were increased in KCs harvested from burn group after stimulation with LPS compared with those from sham group. In vivo administration of SB203580 markedly suppressed both the release of TNF-alpha and IL-1beta and the mRNA expressions of TNF-alpha and IL-1beta in KCs from both sham and burn rats. p38 MAPK activity in KCs was abolished by administration with SB203580, whereas JNK was not.

CONCLUSIONSp38 MAPK signal transduction pathway mediates KCs production of proinflammatory cytokines TNF-alpha and IL-1beta in severely burned rats.

Animals ; Blotting, Western ; Burns ; enzymology ; physiopathology ; Disease Models, Animal ; Enzyme-Linked Immunosorbent Assay ; Interleukin-1 ; genetics ; metabolism ; Kupffer Cells ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Tumor Necrosis Factor-alpha ; genetics ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism ; physiology

OBJECTIVETo observe the role of Kupffer cells in the postburn production of TNFalpha, IL-1beta and IL-6 in severely scalded rats.

METHODS(1) The production of TNFalpha, IL-1beta and IL-6 from rat Kupffer cells stimulated by burn serum was observed. (2) The postburn change in the expression of cytokine mRNA from rat Kupffer cells was monitored. (3) The change in the plasma cytokine contents in scalded rats was determined after the application of gadolinium chloride, a specific inhibitor of Kupffer cells.

RESULTSKupffer cells could be stimulated by burn serum to release cytokines TNFalpha, IL-1beta and IL-6. The mRNA expression of TNFalpha, IL-1beta and IL-6 from rat Kupffer cells increased significantly after injury. But the postburn plasma levels of TNFalpha, IL-1beta and IL-6 decreased obviously to 34.71%, 36.99% and 33.7% of those in scalding group, respectively, after the Kupffer cell activity was inhibited.

CONCLUSIONThe plasma cytokines, i.e. TNFalpha, IL-1beta and IL-6, were primarily produced from Kupffer cells after injury in scalded rats, initiated by TNFalpha, IL-1beta and IL-6 mRNA transcription.

Animals ; Burns ; immunology ; metabolism ; Gadolinium ; pharmacology ; Interleukin-1 ; biosynthesis ; genetics ; Interleukin-6 ; biosynthesis ; genetics ; Kupffer Cells ; physiology ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; biosynthesis ; genetics

OBJECTIVESTo observe the synthesis of Toll-like receptor (TLR) 4 protein and its mRNA expression in Kupffer cells (KCs) and evaluate the role of TLR 4 in liver injury to rats through alcohol-induced liver disease.

METHODSTwenty-eight Wistar rats were divided into two groups: ethanol-fed (group E) and control (group C). Group E rats were given ethanol at a dose of 5 - 12 g x kg(-1) x d(-1), while group C received dextrose. Animals from both groups were killed at 4 and 8 weeks. The KCs were isolated and synthesis of TLR 4 protein was determined by laser scanning confocal microscopy. TLR 4 mRNA expression in KCs was determined by reverse transcription polymerase chain reaction (RT-PCR) analysis. The levels of endotoxin, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in plasma were determined. Changes in liver pathology were observed.

RESULTSLaser scanning confocal microscopy showed that the intensity of fluorescence of TLR 4 protein in group E was stronger than group C. Ethanol administration led to a significant increase in TLR 4 mRNA expression in group E compared with group C (P < 0.05). The concentrations of plasma endotoxin, TNF-alpha and IL-6 were higher in group E than in group C (P < 0.05). Liver sections from rats in group E demonstrated marked pathological changes.

CONCLUSIONEthanol administration can lead to the synthesis of TLR 4 protein and its gene expression in KCs, indicating that TLR 4 may play a major role in the development of alcohol-induced liver injury.

Animals ; Drosophila Proteins ; Female ; Interleukin-6 ; blood ; Kupffer Cells ; physiology ; Lipopolysaccharide Receptors ; physiology ; Liver Diseases, Alcoholic ; etiology ; pathology ; Membrane Glycoproteins ; genetics ; physiology ; RNA, Messenger ; analysis ; Rats ; Rats, Wistar ; Receptors, Cell Surface ; genetics ; physiology ; Toll-Like Receptor 4 ; Toll-Like Receptors ; Tumor Necrosis Factor-alpha ; analysis