肝切除术后肝再生对大鼠结肠癌肝转移灶生长的影响

目的 探讨肝再牛进程触发大鼠结肠痛肝转移残肝内隐性转移灶进展的发生机制.方法 采用肝包膜下种植建立结肠癌肝转移大鼠模型,随机分为假手术组、37%肝切除组和70%肝切除组;采用腹膜后注射建市结肠癌腹膜后转移模型,随机分为假手术组和70%肝切除组.手术后3周处死动物,测定肝内转移瘤量、再生肝重及腹膜后瘤结节重.在含有肝切除后24 h和14 d的门静脉血清培养基中进行结肠癌细胞Lovo体外培养,5.溴脱氧尿核苷(5-BrdU)DNA掺入法检测细胞增殖反应.结果 手术切除明显促进70%肝切除组肝内残留癌牛长(P<0.05),对37%肝切除组肝内残留癌和结肠癌腹膜后转移瘤牛长无促进作用(P>0.05);肝切后24 h门静脉血清组5-BrdU DNA掺人率从第72小时开始增加,至第120小时呈持续增加趋势(P<0.05);肝切后14 d门静脉血清对结肠癌细胞生长无明显刺激作用(P>0.05).结论 结肠癌肝转移切除术后可诱发肝内微小残留灶的进展,并不通过血液循环全身性释放,对肝外转移瘤并不发挥作用.肝切除范围与诱发肿瘤生长有关,只有肝切除达到一定程度时,才足以刺激肿瘤生长.     

Muramyl tripeptide: an effective immunotherapy in the surgical setting for pediatric abdominal neoplasms

A potential complication of intraperitoneal neoplasms is the occurrence of peritoneal metastases. This experiment hypothesizes that resident peritoneal macrophages, activated by muramyl tripeptide (MTP-PE), will destroy peritoneal tumor. MTP-PE is a lipophilic derivative of the mycobacteria cell wall component responsible for induction of cellular immunity and activation of macrophages to a tumoricidal state. A transplantable murine fibrosarcoma, MCA-F was utilized. Murine hosts were challenged intraperitoneally with 5 X 10(3) MCA-F cells. Treatment with MTP-PE micelles or liposome-encapsulated MTP-PE was initiated 48 hours prechallenge and on the day of tumor challenge and continued at 72 hour intervals for the subsequent 21 days. Hosts were observed for survival. At 45 days after tumor challenge, all untreated control animals had succumbed to overwhelming neoplastic disease. In contrast, 30% of the mice treated with liposome-encapsulated MTP-PE (P less than .05) and 50% of the animals treated with MTP-PE micelles (P less than .001) remained alive at 60 days. Followed for 120 days, 20% of MTP-PE micelle treated mice are long-term survivors. These results suggest that control of intraperitoneal seedings may be achieved with MTP-PE when the tumor burden is small.     

High expression of the CD14 gene and interleukin-1beta gene in the liver and lungs of cirrhotic rats after partial hepatectomy

BACKGROUND: A hepatic resection is invasive for cirrhotic patients because postoperative complications, such as hepatic disturbance sometimes resulting in hepatic failure and pulmonary disturbances, are frequent and serious. We investigated here the alteration of the CD14 and inflammatory cytokine genes expressed in the liver and lungs after partial hepatectomy (PH) of a cirrhotic rat model to help elucidate the pathophysiological change occurring during the postoperative course of hepatectomized cirrhotic patients. MATERIALS AND METHODS: Wistar rats were orally administrated carbon tetrachloride once a week for 14 weeks to induce liver cirrhosis. In comparison with cirrhotic and normal rats, we analyzed the expression of the CD14, tumor necrosis factor-alpha, and interleukin (IL)-1beta genes in remnant liver and whole lung tissue during 48 h after 30% partial hepatectomy with Northern blottings and measured asparatate aminotransferase (AST) in serum for evaluation of postoperative hepatic injury. Gadolinium chloride (GdCl3; 7 mg/kg body weight) was intravenously injected 24 h before partial hepatectomy to suppress Kupffer cells (KC) activation. RESULTS: The expression of the CD14 and IL-1beta genes moderately increased at 6 h and peaked at 12 h in parallel with the time course of AST values after PH only in cirrhotic rats. GdCl(3) significantly inhibited the elevation of AST similar to the inhibition of the expression of the CD14 and IL-1beta genes after PH. In addition, the expression of these genes showed marked enhancement in the lungs of the cirrhotic hepatectomy model. CONCLUSIONS: KC activation was responsible for hepatic injury after PH, and the CD14 system appeared to be an early trigger for KC activation followed by induction of inflammatory cytokine IL-1beta synthesis leading to hepatic injury. Furthermore, the CD14 system was suggested to participate in respiratory disturbances after hepatectomy in cirrhosis.     

善宁对大鼠肝部分切除术后种植性肝癌作用的实验研究

目的 探讨生长抑素类似物善宁对肝部分切除术后种植性肝癌的作用及其相关机制。方法 以Wistar大鼠种植性肝癌模型为研究对象,将64只雄性Wistar大鼠随机分为4组,每组16只。A组行单纯右肝叶肿瘤移植,B、C、D组均行左肝叶切除加右肝叶肿瘤种植。C、D组分别为术后12h、72h开始首次善宁治疗组（50ug/kg,腹腔内注射,每日2次）。A、B组为对照组（生理盐水,方法与剂量同上）。结果 术后1周,A组肿瘤体积明显小于B、C、D组（P＜0．01）。C、D组的肿瘤体积明显小于B组（P＜0．01）,而肿瘤细胞的凋亡率则明显高于B组（P＜0．01）。C组与D组的肿瘤体积和细胞凋亡率之间亦存在显著差异（P＜0．01）。结论 善宁可以抑制术后肝肿瘤的生长。     

Hepatic resection but not radiofrequency ablation results in tumor growth and increased growth factor expression

OBJECTIVE: The purpose of this study was to examine the effects of radiofrequency ablation (RFA) on tumor growth and growth factor expression in a murine model. BACKGROUND: Surgical excision remains the only potentially curative therapy for hepatic malignancies. Tumor growth in the remaining liver may be accelerated after resection. The mechanism of this enhanced tumor growth remains unexplained, although growth factors that are released after hepatic resection (which facilitate liver regeneration) may play a role in residual tumor growth. RFA has become a viable alternative for patients who are not candidates for a curative resection. The effect of RFA on tumor growth and growth factor expression has not been studied. METHODS: Hepatic tumors were established by direct injection with CT-26, a murine adenocarcinoma. Tumors were treated by either partial hepatic resection (PH) or RFA. Hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) expression was measured at selected time intervals post-treatment. Tumor growth was measured by reinjection of CT-26 into the residual liver after treatment. Nine days after reinjection, tumor volume was calculated and compared with nontreated controls. RESULTS: HGF and bFGF expression was significantly higher at baseline in the CT-26 tumor-bearing mice when compared with non-tumor-bearing controls (P = 0.00001 and P = 9 x 10, respectively). There was an increase in HGF and bFGF expression at 24 hours (P = 0.005, and P = 0.001) in the PH group. In the RFA group, there was a decrease in HGF and bFGF expression at 24 and 72 hours (P = 0.001 and P = 0.002). Tumor growth comparisons revealed an increase in tumor growth in the hepatectomy group (P = 0.006) but not the RFA group (P = 0.2). CONCLUSIONS: Baseline growth factor expression in tumor-bearing mice is exponentially higher when compared with non-tumor-bearing controls. HGF and bFGF expression are increased posthepatectomy, and decreased post-RFA. Partial hepatectomy results in an increase in tumor growth in the residual liver. RFA did not increase tumor growth after treatment. While hepatectomy is the only curative option for patients with hepatic malignancies, it may accelerate growth of microscopic residual disease.     

Altered Kupffer cell function in biliary obstruction

BACKGROUND: An altered Kupffer cell (KC) response is thought to be responsible for the characteristic phenotype observed after biliary obstruction: a phenotype marked by a defect in the hepatic reticuloendothelial system and a hypersensitivity to endotoxin. Few studies, however, have directly examined KC function. We have sought to define the specific alterations in function and phenotype that occur in the KC after biliary obstruction. METHODS: KCs were isolated from female C57BL/6 mice 4 days after a sham or common bile duct ligation (CBDL) operation. Phagocytosis, oxidative burst potential, and intracellular bacterial killing were measured as markers of reticuloendothelial system function. The KC response to endotoxin was assessed by measuring tumor necrosis factor alpha and interleukin 6 levels in the media after stimulation with lipopolysaccharide (LPS) or with LPS plus LPS-binding protein (LBP). RESULTS: CBDL KCs demonstrated a significant increase in phagocytic ability and significantly decreased baseline oxidative stress, compared with Shams. The oxidative burst potential, however, was equivalent or higher for CBDL KCs. CBDL KCs also demonstrated increased numbers of viable intracellular bacteria after infection; however, it is unclear if this finding represents impaired intracellular bacterial killing or increased phagocytosis of bacteria. With respect to the KC response to endotoxin, CBDL KCs were found to be less sensitive to the stimulatory effects of LPS alone but were exquisitely sensitive to the effects of LBP. LBP levels were found to be significantly elevated in CBDL animals, and CBDL KCs demonstrated a dose-dependent, exaggerated tumor necrosis factor alpha and interleukin 6 response to LPS administered with LBP. CONCLUSIONS: KC function is clearly altered after biliary obstruction. Phagocytic ability is actually increased, although the ability of CBDL KCs to kill bacteria within the phagosome remains ill defined. CBDL KCs are exquisitely sensitive to the effects of LBP, and LBP levels are elevated after biliary obstruction. LBP may be responsible for the increased proinflammatory response observed after endotoxin challenge in animals with biliary obstruction.     

Ischemia-reperfusion of small liver remnant promotes liver tumor growth and metastases--activation of cell invasion and migration pathways.

Elucidating the mechanism of liver tumor growth and metastasis after hepatic ischemia-reperfusion (I/R) injury of a small liver remnant will lay the foundation for the development of therapeutic strategies to target small liver remnant injury, and will reduce the likelihood of tumor recurrence after major hepatectomy or liver transplantation for liver cancer patients. In the current study, we aimed to investigate the effect of hepatic I/R injury of a small liver remnant on liver tumor development and metastases, and to explore the precise molecular mechanisms. A rat liver tumor model that underwent partial hepatic I/R injury with or without major hepatectomy was investigated. Liver tumor growth and metastases were compared among the groups with different surgical stress. An orthotopic liver tumor nude mice model was used to further confirm the invasiveness of the tumor cells from the above rat liver tumor model. Significant tumor growth and intrahepatic metastasis (5 of 6 vs. 0 of 6, P=0.015), and lung metastasis (5 of 6 vs. 0 of 6, P=0.015) were found in rats undergoing I/R and major hepatectomy compared with the control group, and was accompanied by upregulation of mRNA levels for Cdc42, ROCK (Rho kinase), and vascular endothelial growth factor, as well as activation of hepatic stellate cells. Most of the nude mice implanted with liver tumor from rats under I/R injury and major hepatectomy developed intrahepatic and lung metastases. In conclusion, hepatic I/R injury of a small liver remnant exacerbated liver tumor growth and metastasis by marked activation of cell adhesion, invasion, and angiogenesis pathways.     

Deceleration of Regenerative Response Improves the Outcome of Rat with Massive Hepatectomy

Small residual liver volume after massive hepatectomy or partial liver transplantation is a major cause of subsequent liver dysfunction. We hypothesize that the abrupt regenerative response of small remnant liver is responsible for subsequent deleterious outcome. To slow down the regenerative speed, NS‐398 (ERK1/2 inhibitor) or PD98059 (selective MEK inhibitor) was administered after 70% or 90% partial hepatectomy (PH). The effects of regenerative speed on liver morphology, portal pressure and survival were assessed. In the 70% PH model, NS‐398 treatment suppressed the abrupt replicative response of hepatocytes during the early phase of regeneration, although liver volume on day 7 was not significantly different from that of the control group. Immunohistochemical analysis for CD31 (for sinusoids) and AGp110 (for bile canaliculi) revealed that lobular architectural disturbance was alleviated by NS‐398 treatment. In the 90% PH model, administration of NS‐398 or PD98059, but not hepatocyte growth factor, significantly enhanced survival. The abrupt regenerative response of small remnant liver is suggested to be responsible for intensive lobular derangement and subsequent liver dysfunction. The suppression of MEK/ERK signaling pathway during the early phase after hepatectomy makes the regenerative response linear, and improves the prognosis for animals bearing a small remnant liver.     

Glycine attenuates endotoxin-induced liver injury by downregulating TLR4 signaling in Kupffer cells

BACKGROUND: Several experimental studies have observed better outcomes after glycine treatment in patients with endotoxin-induced liver injuries, but its molecular mechanism is not yet fully understood. The purpose of this study was to evaluate the hypothesis that glycine attenuates endotoxin-induced liver injury by affecting endotoxin signal transduction in liver macrophages. METHODS: An animal model of endotoxin-induced liver injury was established by intraperitoneally injecting mice with 10 mg/kg body weight endotoxin fed a pretreatment diet with or without 5% (w/w) glycine. Blood and liver samples were obtained for analysis of liver morphology and to determine concentrations of alanine aminotransferase, endotoxin receptor Toll-like receptor 4 (TLR4), tumor necrosis factor-alpha (TNF-alpha), and interleukin (IL)-10 at various time points after injection. To investigate the effect of glycine on liver macrophages, Kupffer cells (KCs) were isolated and challenged by LPS (100 ng/mL), with or without glycine (4 mmol/l) pretreatment, and the expressions of TLR4, IL-10, and TNF-alpha were assayed at mRNA and protein levels. DNA-binding activity of nuclear factor-kappa B (NF-kappaB) was also analyzed using enzyme-linked immunosorbent assay. RESULTS: Dietary glycine significantly improved the survival rate of endotoxemic mice (P < .05), whereas serum alanine aminotransferase and TNF-alpha levels were significantly decreased at different time points (P < .05); IL-10 levels were increased (P < .05). Concurrently, LPS-induced hepatic tissue injury was attenuated as indicated by morphologic analysis; secretion of IL-10 in liver tissue (P < .05) was enhanced; and expression of TLR4 and TNF-alpha in liver tissue was downregulated (P < .05). Consistent with these in vivo experiments, enhanced secretion of IL-10 and inhibited expression of TLR4 and TNF-alpha caused by glycine pretreatment were also observed in LPS-stimulated KCs. NF-kappaB DNA-binding activity was also significantly inhibited by glycine (P < .05, respectively). CONCLUSIONS: Dietary glycine improved survival rates and liver function in endotoxemic mice by regulating the production of proinflammatory or anti-inflammatory cytokines in liver. It attenuated liver injury by deactivating KCs through inhibiting TNF-alpha secretion and increasing IL-10 production. The downregulative effect of glycine on the endotoxin signaling pathway and TLR4/NF-kappaB/TNF-alpha may be a novel potential mechanism by which glycine inhibits KC activity.     

Efficacy of multiagent herpes simplex virus amplicon-mediated immunotherapy as adjuvant treatment for experimental hepatic cancer

OBJECTIVE: To evaluate the use of herpes simplex viral (HSV) amplicon vectors for production of tumor vaccines and to determine if such vaccines expressing combinations of immunostimulatory agents may be effective in the treatment of experimental liver cancer. METHODS: A hepatic metastatic tumor model using CT-26 colorectal cancer in syngeneic Balb/C mice was utilized. Tumor vaccines were produced by brief (20 minutes) exposure of irradiated tumor cells to herpes amplicon vectors carrying the transgene for RANTES, B7.1, or GM-CSF. The antitumor efficacy of vaccination using tumor cells secreting GM-CSF (single agent) or a combination of RANTES/B7.1/GM-CSF (multiagent) was tested. The effect of 60% hepatectomy or T-cell depletion was also tested in this model. RESULTS: In vitro assays confirmed high-level cytokine or costimulatory molecule production by cells transduced with amplicons. Antitumor efficacy was observed with single-agent or multiagent treatment. Without hepatectomy, immunization with single-agent or multiagent vaccine therapy appears equivalent. When administered in the setting of hepatectomy, multiagent regimens produced a higher cure rate than single-agent therapy (50% vs. 12.5%, =.03). Animals treated with GM-CSF alone had an average nodule count of 40 +/- 19 ( <.006 vs. Hep control 232 +/- 30), while animals treated with multiagent therapy had an average nodule count of 11 +/- 7 ( <.0004 vs. control). CD4 and CD8 lymphocyte blockade abrogated observed efficacy, confirming a lymphocyte-mediated response. CONCLUSIONS: Tumor vaccines produced using HSV amplicon-mediated gene transfer may be useful in the treatment of liver malignancies. In the setting of hepatectomy, multiagent vaccine therapy offers an advantage over single-agent therapy. These data encourage consideration of such HSV-based neoadjuvant immunotherapy for treatment of liver malignancies.     

Liver pathology and cell proliferation after calcineurin inhibitors and antiproliferative drugs following partial hepatectomy in rats

Immunosuppressants are the cornerstones of treatment after solid organ transplantation. This study investigated the pathology and cell proliferation following partial hepatectomy (PH) in rats undergoing immunosuppressive treatment. After 1 day, all rats were subjected to 70% PH. Groups A and B (n = 10) received calcineurin inhibitors subcutaneously: either FK506 or cyclosporine (CyA). Groups C and D (n = 10) received antiproliferative drugs: either mycophenolate mofetil (MMF) or sirolimus (SRL) by gavage. A control group (n = 5) received 1 mL of tap water daily. On postoperative day 2, all rats were sacrificed to obtain liver tissue for pathologic examination. Using immunohistochemistry we separately examined the hepatectomy surface and the liver parenchyma. In the parenchyma, the Ki-67 indices were higher in the CyA and FK506 groups and lower in the SRL and MMF groups compared with controls (P < .01). CyA had the highest and MMF the lowest values. On the hepatectomy surface, Ki-67 indices and TGF-alpha expressions were higher in the CyA group and lower in the SRL and MMF groups compared with the control group (P < .01). Slightly higher values in the FK506 group were not significantly different compared with the control group (P > .05). All groups other than FK506 showed prominent cholangiolar epithelial phenotypes compared with the control group. In the CyA and SRL groups, the number of cholangiolar cells was higher (P < .01), and in the MMF group lower than in the control group (P < .01). Among all groups, SRL had the highest values.     

Effect of hepatectomy on the reticuloendothelial system of septic rats

The purpose of this study was to evaluate the function of the reticuloendothelial system (RES) of sham hepatectomy and 20% and 50% partial hepatectomy (PH 20%, PH 50%), with or without cecal ligation and puncture-induced sepsis. The animals were injected with 51Chromium sheep red blood cells (SRBC) at 72 hours. SRBC half life (T1/2) was measured as an index of RES function and the percentage distribution of SRBC in liver, lung, and spleen was calculated. T1/2 was significantly prolonged in PH 50% rats and was associated with decreased radioactive uptake by the liver. Mortality was nil in the control groups and markedly increased in the presence of sepsis. The results suggest that decreased RES function following hepatectomy is dependent upon the proportion of liver removed and that sepsis further increased the mortality of hepatectomized animals.     

Rapamycin Inhibits Hepatectomy-Induced Stimulation of Metastatic Tumor Growth by Reduction of Angiogenesis, Microvascular Blood Perfusion, and Tumor Cell Proliferation

Background  Liver regeneration after hepatectomy stimulates metastatic tumor growth through the release of potent growth factors. In the signaling cascades of several growth factors, mTOR is a downstream mediator, triggering cell survival and cell cycle progression. The mTOR inhibitor rapamycin (RAPA) has been shown to exhibit potent antitumor activities. However, it is unknown whether RAPA is capable of exerting these effects under the conditions of hepatectomy-associated liver regeneration. We therefore analyzed the effect of RAPA and cyclosporine A (CyA) on tumor growth characteristics after major hepatectomy using a mouse model of colorectal metastasis. Methods  Tumor growth was studied by using GFP-transfected CT26.WT colorectal cancer cells, which were implanted into the dorsal skinfold chambers of BALB/c-mice after 70% hepatectomy. The animals were treated daily with RAPA (1.5 mg/kg) or CyA (10 mg/kg). Tumors were analyzed for angiogenesis, microvascular blood perfusion, cell proliferation, apoptotic cell death, and tumor growth. Results  RAPA significantly inhibited tumor growth compared with CyA and sham treatment. This was associated with a decreased microvascular density within the tumors and a markedly reduced microvascular blood perfusion. CyA only slightly reduced angiogenesis and tumor growth. The effects of RAPA were associated with a significant reduction of tumor cell proliferation, whereas manifestation of apoptotic cell death was not affected by the immunosuppressive treatment regimen. Conclusions  RAPA is capable of inhibiting angiogenesis, microvascular blood perfusion, and tumor growth of colorectal metastasis during hepatectomy-associated liver regeneration. Thus, targeting mTOR might represent an interesting strategy to prevent tumor recurrence after hepatectomy for colorectal metastasis.     

Kupffer cell blockade prevents induction of portal venous tolerance in rat cardiac allograft transplantation

Pretransplant portal venous (pv) administration of donor antigen induces allospecific partial tolerance. Although the involved mechanism has not been defined, antigen presentation by Kupffer cells (KC) in the liver is considered to be critical. We evaluated the effect of KC blockade on this pv tolerance induction in Buffalo (RT1b) rats receiving Lewis (RT1(1] cardiac heterotopic allografts. Control rats received no treatment, while experimental animals received 25 X 10(6) ultraviolet B-irradiated (12,000 J/m2) donor spleen cells via either the iv (systemic intravenous) or the pv routes 7 days before transplantation. Gadolinium chloride (GdCl3), a rare earth metal known to inhibit KC phagocytosis, was given (7 mg/kg) 1 and 2 days before pv preimmunization. Cardiac graft prolongation was obtained by pv (MST = 13.3 +/- 1.9 days, n = 6, vs control = 7.3 +/- 0.5 days, n = 6; P less than 0.001) but not by iv preimmunization (7.7 +/- 0.7 days, n = 6, NS vs control). KC blockade abolished the pv tolerance, as indicated by abrogation of graft prolongation (PV + GdCl3 = 8.0 +/- 0.8 days, n = 6, NS vs control). These findings suggest that effective alloantigen uptake by KC in the liver is essential for the induction of pv tolerance in rat cardiac transplantation.     

Importance of timing and length of administration of angiogenesis inhibitor TNP-470 in the treatment of K12/TRb colorectal hepatic metastases in BD-IX rats.

BACKGROUND: The timing and length of administration of angiogenesis inhibitor TNP-470 was altered to evaluate the effect on disease progression in a rat model of colorectal hepatic metastases. METHODS: Pair-fed BD-IX rats, injected intrasplenically with rat colon adenocarcinoma K12/TRb cells at day 0, were randomized to receive subcutaneous injections of either placebo or 15 mg/kg TNP-470 on alternate days: for 2 weeks beginning 24 hours after tumor inoculation ("Early"), for 4 weeks beginning 24 hours after tumor inoculation ("Prolonged"), or for 2 weeks beginning at day 15 after macroscopic tumor nodules were confirmed ("Delayed"). Response to treatment was evaluated by counting tumor nodules on the surface of the liver at laparotomy on day 14 and 28 after tumor inoculation. The animals were followed for survival and cause of death. RESULTS: Maximal suppression of hepatic metastases at day 28 required 4-week rather than 2-week TNP-470 administration. Prolonged TNP-470 administration resulted in significantly fewer hepatic metastases at day 28 compared to control (P < .05). Early and prolonged TNP-470 improved survival (Wilcoxon test, P < .05) compared with delayed TNP-470 and placebo. Delayed TNP-470 administration did not increase survival or significantly diminish the number of metastases at day 28 compared with placebo. CONCLUSIONS: These data suggest that prolonged adjuvant antiangiogenic therapy may suppress colorectal hepatic micrometastases.     

Autoregulation by eicosanoids of human Kupffer cell secretory products. A study of interleukin-1, interleukin-6, tumor necrosis factor-alpha, transforming growth factor-beta, and nitric oxide.

OBJECTIVE: Methods employed previously to analyze the secretory behavior of rodent Kupffer cells (KC) were used to examine the human KC's secretory response to lipopolysaccharide (LPS). SUMMARY BACKGROUND DATA: As the resident hepatic macrophage, the KC resides at the interface between the portal and systemic circulations. Consequently, this cell may play an integral role in the immune response to antigens and bacteria in the sinusoid. Study of cytokine production by the KC has relied predominantly on the rat as the source of these cells. Whether human KCs respond similarly to rat KCs after LPS stimulation has been a matter of speculation. METHODS: Kupffer cells obtained from seven human livers were tested under conditions identical to those used to study rat KCs. Kupffer cells rested for 12 hours after isolation were stimulated with LPS (2.5 micrograms/mL). Arginine concentration in the culture medium varied from 0.01 to 1.2 mM. To examine the role of eicosanoids, parallel culture wells received indomethacin (10 microM). Culture supernatants were assayed for interleukin-1 (IL-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), prostaglandin E2 (PGE2), and nitric oxide. RESULTS: Similar to the rat KC, LPS-stimulated human KCs released IL-1, IL-6, TNF-alpha, TGF-beta, and PGE2. However, unlike rat KCs, nitric oxide could not be detected, regardless of whether the human KCs were exposed to LPS, interferon-gamma (INF-gamma), or LPS + IFN-gamma. Similar to rat KCs, indomethacin prevented PGE2 release while significantly upregulating TNF-alpha, IL-1, and IL-6, but not TGF-beta, consistent with an autoregulatory control of eicosanoids over proinflammatory cytokines. As has been shown in the rat, physiologic levels of L-arginine (0.01 mM) significantly enhanced LPS-induced PGE2 secretion relative to the response in medium containing standard L-arginine concentration (1.2 mM); however, unlike the rat KC, the human's cytokine response to LPS was not downregulated by this enhanced PGE2 release. CONCLUSIONS: Although many functional features are shared by rat and human KCs, significant differences do exist. Such discrepancies reinforce the need to proceed with caution when generalizing from the results obtained in other species to human physiology.     

Functional heterogeneity of the kupffer cell population is involved in the mechanism of gadolinium chloride in rats administered endotoxin

BACKGROUND: The purpose of this study was to determine if evidence of functional heterogeneity between subtypes of the Kupffer cell (KC) may be involved in the mechanism of the protective effect of gadolinium chloride (GdCl3) in endotoxemia. METHODS: Rats pretreated with or without GdCl3 were administered lipopolysaccharide (LPS) or vehicle. Serum and liver tissues were collected after LPS administration for cytokine measurements and pathological and immunohistochemical evaluation. RESULTS: After LPS administration, increases in expression of TNF-alpha and IL-6 mRNA in the liver were blunted significantly by GdCl3. In control liver tissue, ED2-positive cells were a predominant fraction, with a few ED1-positive cells, and GdCl3 eliminated only ED2-positive cells. Further, ED2-positive cells were larger in size than ED1-positive ones. Importantly, the number of ED1-positive cells in the liver was increased about threefold in the control group but not in the GdCl3 group after LPS injection. Intermediate or large KCs isolated by counterflow centrifugal elutriation showed greater capacity for phagocytosis and production of superoxide and TNF-alpha than small ones. In contrast, IL-6 production was increased to a greater extent in small than in intermediate or large cells. GdCl3 eliminated the intermediate or large KC subpopulation predominantly. CONCLUSION: Collectively, functional heterogeneity of the KC population was involved in the mechanism of the protective effects of GdCl3 in endotoxemia. TNF-alpha derived from activated intermediate or large KCs may activate small KCs and the latter may be recruited to other organs, such as lungs and kidneys, and produce a large amount of IL-6, leading to multiple organ failure.     

Liver regeneration stimulates tumor metastases

BACKGROUND: Partial hepatectomy for patients with colorectal liver metastases is associated with a tumor recurrence rate approaching 80% post-resection. Different factors and phases associated with regeneration of the liver are implicated in tumor recurrence. This study investigates the effects of the early and late phases of liver regeneration and the impact of the degree of liver resection on stimulating tumor growth and metastasis. MATERIALS AND METHODS: Groups of mice underwent partial hepatectomy (37% or 70%) and were then challenged with colorectal liver carcinoma (CRC) tumors immediately after liver resection (early and late phase effect) or 6 days post liver resection (late phase effect). Tumor growth, degree of proliferation, tumor morphology, and the presence of extrahepatic metastases were investigated 21 days post-tumor induction. RESULTS: The late phase of liver regeneration plays a significant role in tumor stimulation and metastasis. The degree of hepatectomy also appears to be an important factor. The degree of hepatic resection significantly influences tumor growth and the extent of extrahepatic metastases, particularly in the lungs. CONCLUSIONS: Elucidation of the processes involved in the late phase of liver regeneration may assist in the development and timing of adjuvant agents to minimize tumor recurrence during this phase.