Ghrelin对心肌梗死后心肌重塑及心脏功能的影响及其机制研究

目的:观察ghrelin对心肌梗死(MI)大鼠心肌重塑和心脏功能的影响,并探讨其可能的机制。方法:应用冠状动脉结扎术创建大鼠MI模型,并设立假手术组作为对照;造模成功后每天2次注射ghrelin(100μg/kg),持续4周,以此作为MI-ghrelin组,并以每天注射生理盐水的MI大鼠作为MI-生理盐水组。检测和比较各组大鼠左心室重塑和血流动力学的改变情况;非梗死心肌中白介素(IL)-1β、肿瘤坏死因子-α(TNF-α)、基质金属蛋白酶(MMP)-2、MMP-9 mRNA和蛋白的表达;梗死边界心肌细胞的凋亡情况。结果:Ghrelin可使心肌梗死后的MI大鼠降低的缩短分数(FS)、左室内压最大变化率均显著下降(dP/dtmax)、疤痕厚度明显升高,增加左室舒张末压(LVEDP)、左室收缩末内径(LVESD)、左室舒张末期内径(LVEDD)、梗死边界心肌细胞的凋亡指数显著降低。此外,ghrelin可抑制心肌梗死后的MI大鼠非梗死心肌中白介素(IL)-1β、肿瘤坏死因子-α(TNF-α)、质金属蛋白酶(MMP)-2和MMP-9的mRNA和蛋白的表达。结论:Ghrelin可缓解MI后大鼠LV功能紊乱及心室重塑,这可能与其抑制炎症反应及基质金属蛋白酶的表达有关。     

Enhancement of endotoxin-induced vascular hyporeactivity to phenylephrine in the thoracic aortas of Mg-deficient rats ex vivo

Since endotoxin lethality is enhanced by Mg deficiency in animals, we determined whether endotoxin-induced vascular hyporeactivity to phenylephrine (PE) is enhanced in Mg-deficient rats. Normal and Mg-deficient adult male Wistar rats were injected with Escherichia coli 011: B4 lipopolysaccharide (1 or 5 mg/kg, i.p.). Six h later, rings prepared from their thoracic aortas showed severe hyporeactivity to PE. This was more pronounced in the Mg-deficient rats, and was reversed by in vitro treatment with a highly selective inducible nitric oxide (NO) synthase inhibitor, 1400 W, or a highly selective soluble guanylyl cyclase inhibitor, ODQ. However, reversal required high doses of both inhibitors in Mg-deficient rats. Endotoxemia for 6 h was associated with elevated serum interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha levels, and strong TNF receptor mRNA expression in the abdominal aortas, which were significantly greater in the Mg-deficient rats. Treatment of the thoracic aortas, isolated from control and Mg-deficient rats before endotoxic challenge, with IL-1beta or TNF-alpha for 6 h in vitro caused hyporeactivity to PE, but its severity did not differ significantly between the two groups. These results suggest that high serum IL-1beta and TNF-alpha levels, and increased TNF receptor production in the vascular tissue, contribute to vascular hyporeactivity to PE in endotoxemia, and to its enhancement in Mg-deficient rats, via NO/cGMP signaling.     

Acute and chronic influence of hemodialysis according to the membrane used on phagocytic function of neutrophils and monocytes and pro-inflammatory cytokines production in chronic renal failure patients

This work evaluated the phagocytic capacity of monocytes and neutrophils, and tumor necrosis factor-alpha, interleukin 6, 1 and 8 serum levels in chronic renal failure patients under peritoneal dialysis and hemodialysis treatment, compared with chronic renal failure patients without dialysis treatment and healthy individuals, in order to contribute to a better understanding of the action of these therapies on the evolution of chronic renal failure patients. All patients with chronic renal failure (under dialysis or not) showed decreased phagocytic capacity of neutrophils and monocytes. All those in hemodialysis (cellulose acetate or polysulfone membranes) showed a decreased phagocytic capacity. The phagocytic index for neutrophil was 13 times lower than that of the control group for both membranes, whereas for monocytes, only those using polysulfone membrane showed a significant decrease of 4.9 times in phagocytic capacity. There was an acute stimulation of the phagocytosis by neutrophils after a single session of dialysis with both types of membrane, while only cellulose acetate membrane decreased the phagocytic index of monocytes after the hemodialysis session. Patients using cellulose acetate showed a chronic increase in tumor necrosis factor-alpha serum levels, while those using polysulfone showed a chronic increase in interleukin 6. After a single hemodialysis procedure, no acute effect of the treatment on tumor necrosis factor-alpha and interleukin 6 levels was identified. The decreased phagocytic function of neutrophils and monocytes may account for the high levels of susceptibility of chronic renal failure patients to infections with pyogenic bacteria and tuberculosis. Furthermore, inflammatory activity may occur with both types of membrane studied, suggesting that it will be useful for these patients to evaluate some anti-inflammatory or anti-cytokine therapies against tumor necrosis factor-alpha and interleukin 6, in order to avoid cardiovascular complication.     

Protein kinases A and C positively regulate G protein-dependent activation of phosphatidylinositol-specific phospholipase C by tumor necrosis factor-alpha in MC3T3-E1 osteoblasts

The role(s) of protein kinases in the regulation of G protein-dependent activation of phosphatidylinositol-specific phospholipase C by tumor necrosis factor-alpha was investigated in the osteoblast cell line MC3T3-E1. We have previously reported the stimulatory effects of tumor necrosis factor-alpha and A1F₄⁻, an activator of G proteins, on this phospholipase pathway documented by a decrease in mass of PI and release of diacylglycerol. In this study, we further explored the mechanism(s) by which the tumor necrosis factor or A1F₄⁻ -promoted breakdown of phosphatidylinositol and the polyphosphoinositides by phospholipase C is regulated. Tumor necrosis factor-alpha was found to elicit a 4–5-fold increase in the formation of [³H]inositol-1,4-phosphate and [³H]inositol-1,4,5-phosphate; and a 36% increase in [³H]inositol-1-phosphate within 5 min in prelabeled cells. [³H]inositol-4-phosphate, a metabolite of [³H]inositol-1,4-phosphate and [³H]inositol-1,4,5-phosphate, was found to be the predominant phosphoinositol product of tumor necrosis factor-alpha and A1F₄⁻ -activated phospholipase C hydrolysis after 30 min. In addition, the preincubation of cells with pertussis toxin decreased the tumor necrosis factor-induced release of inositol phosphates by 53%. Inhibitors of protein kinase C, including Et-18-OMe and H-7, dramatically decreased the formation of [³H]inositol phosphates stimulated by either tumor necrosis factor-alpha or A1F₄⁻ by 90–100% but did not affect basal formation. The activation of cAMP-dependent protein kinase, or protein kinase A, by the treatment of cells with forskolin or 8-BrcAMP augmented basal, tumor necrosis factor-alpha and A1F₄⁻-induced [³H]inositol phosphate formation. Therefore, we report that protein kinases can regulate tumor necrosis factor-alpha-initiated signalling at the cell surface in osteoblasts through effects on the coupling between receptor, G-protein and phosphatidylinositol-specific phospholipase C. J. Cell. Biochem. 65:198–208. © 1997 Wiley-Liss, Inc.     

Uroprotective effect of oleuropein in a rat model of hemorrhagic cystitis

Hemorrhagic cystitis is one of the devastating complications seen after receiving cyclophosphamide chemotherapy. Oleuropein is the most important phenolic compound of olive leaves that mediates most of its beneficial pharmacological properties. Herein, we investigated the possible uroprotective effect of oleuropein against cyclophosphamide induced hemorrhagic cystitis in a rat model. For this purpose, we measured bladder nitric oxide, reduced glutathione, catalase, tumor necrosis factor-alpha and vascular endothelial growth factor levels in addition to the bladder gene expression of intercellular adhesion molecule-1 after induction of hemorrhagic cystitis in the presence or absence of oleuropein. Histopathological examination of bladder tissues was also performed. After cyclophosphamide injection, we demonstrated a significant decrease in bladder reduced glutathione (39%) and catalase (55.4%) levels and a significant increase of nitric oxide (5.6 folds), tumor necrosis factor-alpha (3.3 folds), vascular endothelial growth factor (2 folds) and intercellular adhesion molecule-1 (8 folds) bladder contents when compared to those in normal control rats. Administration of oleuropein induced a marked elevation in bladder reduced glutathione (37.8%), catalase (100.4%) with a prominent reduction of bladder nitric oxide (40%), tumor necrosis factor-alpha (35.9%) and vascular endothelial growth factor (56.2%) levels along with downregulation of intercellular adhesion molecule-1 bladder expression (73.1%) in comparison to cyclophosphamide treated rats levels. Our data demonstrated that oleuropein counteracts the harmful effects of cyclophosphamide on the bladder through its antioxidant and anti-inflammatory activities. Oleuropein exerts a definite uroprotective effect against cyclophosphamide induced hemorrhagic cystitis in rats.     

In vitro and in vivo inhibition of LPS-induced tumor necrosis factor-alpha production by dimeric gallotannin analogues.

Designed dimeric gallotannin analogues featuring two tetragalloylglucopyranose cores connected by various hydrocarbon linkers inhibit tumor necrosis factor-alpha secretion from lipopolysaccharide-stimulated human peripheral blood mononuclear cells by up to 53% (5-24 microM concentration range) compared to control. Comparable suppression of tumor necrosis factor-alpha levels (approximately 50% vs control) was observed in the plasma of rats co-treated with lipopolysaccharide and specific tannin analogues selected for their lack of interleukin 1-beta stimulating activity.     

Enhanced tumor necrosis factor-α production following endotoxin challenge in rats is an early event during magnesium deficiency

Magnesium (Mg) plays an essential role in fundamental cellular reactions and the importance of the immuno-inflammatory processes in the pathology of Mg deficiency has been recently reconsidered. The purpose of the present study was to assess the effect of different stages of Mg deficiency on endotoxin response and tumor necrosis factor-α (TNFα) production. Weaning male Wistar rats were pair fed either a Mg-deficient or a control diet. At day 7, lipopolysaccharide (LPS) induced no lethal effects in control rats but resulted in 70% mortality in Mg-deficient rats within 3 h. The vulnerability of Mg-deficient rats to LPS was associated with higher TNFα plasma values. Mg-deficient animals that received magnesium supplementation before endotoxin challenge had significantly increased survival. At day 2, control and Mg-deficient rats were also subjected to endotoxin challenge with or without magnesium pre-treatment. A significant increase in TNFα plasma level was observed in Mg-deficient rats compared to rats fed the control diet. Mg-deficient rats that received magnesium replacement therapy before endotoxin challenge had significantly lower TNFα plasma values than those receiving saline before endotoxin. Thus, the results of this experiment suggest that the activated or primed state of immune cells is an early event occurring in Mg deficiency.     

不同浓度沙利度胺对大鼠慢性坐骨神经缩窄模型的镇痛效果及机制

目的:比较不同剂量沙利度胺对大鼠慢性坐骨神经缩窄(chronic sciatic nerve constriction,CCI)的镇痛效果及可能机制。方法:将50只大鼠随机分为S组、C组、L组、M组及H组,S组作为假手术组,其余四组建立CCI模型,术后分别用20 mg/kg、50mg/kg、100 mg/kg沙利度胺处理L组、M组、H组。于术后第1、2、3、4周测量和比较各组大鼠机械性痛阈与热痛阈,采用蛋白质印迹法(Western blot)及实时荧光定量PCR(Q-PCR)检测各组大鼠肿瘤坏死因子受体(TNFR)的mRNA和蛋白表达,并分析沙利度胺浓度与TNFR mRNA相对表达的相关性。结果:S组术前术后的机械性痛阈与热痛阈均无明显改变(P0.05),其余四组术后痛阈均较术前明显下降(P0.05);C组术后第4周时机械性痛阈明显升高(P0.05),而术后其他时间点的机械性痛阈与热痛阈无明显差异(P0.05);L组、M组、H组术后机械性痛阈、热痛阈随时间的延长呈上升趋势,差异有统计学意义(P0.05)。术后,C组机械性痛阈与热痛阈对比S组明显降低(P=0.000),亦显著低于L组(P=0.000);而不同剂量组机械性痛阈、热痛阈相比,H组高于M组(P=0.000),M组高于L组(P=0.000)。相对于C组,L组、M组、H组术后第4周TNFR1 mRNA及蛋白相对含量显著下降(P0.05),其中H组下降最为明显,M组次之。Pearson相关性分析结果显示:沙利度胺浓度的增加与TNFR1表达水平的升高呈明显负相关关系(r=-0.497,P=0.036)。结论:沙利度胺可能通过影响TNFR表达水平对大鼠慢性坐骨神经缩窄发挥镇痛效应,其镇痛效应随剂量增加而加强,有望作为神经病理性疼痛的辅助镇痛药物之一。     

Interleukin 1 and Tumor Necrosis Factor-α Stimulate the Production of Colony-Stimulating Factor 1 by Murine Astrocytes

Astrocytes have the ability to secrete colony-stimulating factor 1 (CSF-1), a growth factor known to stimulate the proliferation of brain macrophages. We have studied the effect of cytokines such as interleukin 1 (IL-1), tumor necrosis factor-alpha (TNF alpha), and interleukin 6 (IL-6) on the production of CSF-1 by cultured primary astrocytes and an astrocytic cell line derived from embryonic mouse brain. We observed that both TNF alpha and IL-1 increased CSF-1 mRNA and protein levels in the astrocytic cultures. In contrast, IL-6 was ineffective. The CSF-1 mRNA levels were strongly reduced by incubating immortalized astrocytic cells with staurosporine, a protein kinase C inhibitor, both in the absence and in the presence of cytokines. Conversely, 12-O-tetradecanoylphorbol 13-acetate, a protein kinase C activator, increased CSF-1 mRNA levels. These results suggest a mechanism whereby mononuclear phagocytes could favor their own recruitment in the CNS by producing cytokines.     

Study of the effect of lithium on lymphokine-activated killer cell activity and its antitumor growth.

The in vitro effect of lithium on lymphokine-activated killer cell (LAK) activity and its in vivo antitumor growth were observed. LAK activity was enhanced when LiCl was added during LAK cell induction, and this enhancement was observed both in human peripheral blood mononuclear cell and in mouse splenocytes used as LAK precursors. Cholera toxin, which can increase intracellular levels of cAMP, decreased LAK cell activity. However, lithium partially reversed this inhibitory effect, indicating that lithium increased LAK cell activity by decreasing cAMP levels. D-Sphingosine, an inhibitor of protein kinase C, and EGTA, a calcium chelator, both inhibited the LAK cell activity. However, their inhibitory effects could not be reversed by lithium because lithium was added in the culture in combination with one of these inhibitors during LAK cell induction. By using slot blot analysis, the effect of lithium on the expression of tumor necrosis factor-alpha mRNA of LAK cells was analyzed. Lithium increased the level of tumor necrosis factor-alpha mRNA when both lithium and interleukin 2 were added to induce LAK cells. The in vivo antitumor effect of lithium has also been studied. Using a mouse melanoma experimental model, the effect of lithium on tumor growth was also observed. Both lithium alone and interleukin 2/LAK had an antitumor effect, whereas the treatment of interleukin 2/LAK in combination with lithium had the strongest inhibitory effect on tumor growth, since this treatment resulted in reduction of tumor size and prolongation of survival in tumor-bearing mice. Therefore, it is hopeful that lithium can be used as a new immunomodulator for cancer immunotherapy and immune diseases.     

A novel recombinant snake venom metalloproteinase from Agkistrodon acutus protects against taurocholate-induced severe acute pancreatitis in rats

Severe acute pancreatitis (SAP) remains a challenging disease to manage, with high mortality, limited understanding of pathogenesis and lack of specific therapy. Recombinant fibrinogenase II (rFII) from Agkistrodon acutus venom has been found to degrade tumor necrosis factor-alpha (TNF-α) which is vital in mortality of SAP. Here we investigate the in vivo effects of rFII in rat SAP and confirm the degradation effect of rFII for TNF-α in vitro. The SAP model was prepared by retrograde infusion of 5% sodium taurocholate into the biliopancreatic duct in male Sprague–Dawley rats. Treatment with 1 mg/kg rFII could significantly increase survival rate of SAP rats (P = 0.006) as well as 8 mg/kg Infliximab treatment did. The pancreatic and pulmonary injury and the peritoneal and systemic inflammatory response were also attenuated by rFII as well as Infliximab. Furthermore, rFII inhibited TNF-α secretion by rat peritoneal macrophages in a time- and concentration-dependent manner but didn’t influence interleukin (IL) -1β secretion in vitro. The degradation potency of rFII for human TNF-α was greater than that for rat TNF-α. Our findings suggest that rFII could have protective effect on taurocholate-induced SAP in rats, mainly depending on direct degradation of TNF-α.     

Effect of endothelin antagonism on the production of cytokines in eosinophilic airway inflammation

Endothelin (ET)-1 has been launched as an important mediator in bronchial asthma, which is an eosinophilic airway inflammation. However, the interplay between ET-1 and other proinflammatory mediators during the development of airway inflammation has not been elucidated. We wanted to study 1) whether the production of ET-1 precedes the production of other proinflammatory mediators and 2) whether ET-1 stimulates the production of these mediators within the airways. These hypotheses were studied during the development of an eosinophilic airway inflammation in rats. The increase in ET-1 mRNA level in lung tissue preceded the increase in mRNA levels of tumor necrosis factor-alpha, interleukin (IL)-1beta, and IL-8. Treatment of the animals with the ET receptor antagonist bosentan resulted in a substantial decrease in the concentrations of tumor necrosis factor-alpha, IL-4, IL-1beta, interferon-gamma, and ET-1 in bronchoalveolar lavage fluid. In conclusion, the synthesis of ET-1 as measured by increased mRNA level precedes the synthesis of other proinflammatory cytokines of importance for the development of an eosinophilic airway inflammation, and ET antagonism inhibits the production of these mediators within the airways. Whether treatment with ET antagonists will prove beneficial for patients with eosinophilic airway inflammations like bronchial asthma is not yet known.     

Modulation of sulfur mustard induced cell death in human epidermal keratinocytes using IL-10 and TNF-alpha

We compared the effects of overexpressing a tightly regulated anti-inflammatory cytokine, interleukin 10 (IL-10), and the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) on sulfur mustard induced cytotoxicity in human epidermal keratinocytes. Both cytokines were overexpressed when compared with the cells transfected with the empty vector as determined by quantitative ELISA. Cells overexpressing interleukin 10 suppressed the pro-inflammatory cytokines interleukin 8 and interleukin 6 following exposure to 50-300 microM sulfur mustard. These cells exhibited delayed onset of sulfur mustard induced cell death. On the other hand, cells overexpressing tumor necrosis factor alpha induced a sustained elevation in both interleukin 6 and 8 expression following exposure to 50-300 microM sulfur mustard. These cells were sensitized to the effects of sulfur mustard that resulted in an increased sulfur mustard induced cell death. Normal human epidermal keratinocytes treated with sulfur mustard exhibited elevated levels of tumor necrosis factor alpha expression and increased activity of nuclear factor kappa B. Gene array data indicated that cells overexpressing interleukin 10 induced several genes that are involved in growth promotion and cell-fate determination. We, therefore, identify IL-10 and TNF-alpha signal transduction pathways and their components as possible candidates for early therapeutic intervention against sulfur mustard induced cell injury.     

Inflammatory response following acute magnesium deficiency in the rat

The importance of inflammatory processes in the pathology of Mg deficiency has been recently reconsidered but the sequence of events leading to the inflammatory response remains unclear. Thus, the purpose of the present study was to characterize more precisely the acute phase response following Mg deficiency in the rat. Weaning male Wistar rats were pair-fed either a Mg-deficient or a control diet for either 4 or 8 days. The characteristic allergy-like crisis of Mg-deficient rats was accompanied by a blood leukocyte response and changes in leukocytes subpopulations. A significant increase in interleukin-6 (IL-6) plasma level was observed in Mg-deficient rats compared to rats fed a control diet. The inflammatory process was accompanied by an increase in plasma levels of acute phase proteins. The concentrations of alpha2-macroglobulin and alpha1-acid glycoprotein in the plasma of Mg-deficient rats were higher than in control rats. This was accompanied in the liver by an increase in the level of mRNA coding for these proteins. Moreover, Mg-deficient rats showed a significant increase in plasma fibrinogen and a significant decrease in albumin concentrations. Macrophages found in greater number in the peritoneal cavity of Mg-deficient rats were activated endogenously and appeared to be primed for superoxide production following phorbol myristate acetate stimulation. A high plasma level of IL-6 could be detected as early as day 4 for the Mg-deficient diet. Substance P does not appear to be the initiator of inflammation since IL-6 increase was observed without plasma elevation of this neuropeptide. The fact that the inflammatory response was an early consequence of Mg deficiency suggests that reduced extracellular Mg might be responsible for the activated state of immune cells.     

Disruption of TNF-α signaling improves osteoblastic differentiation of adipose-derived mesenchymal stem cells and bone repair

Adipose tissue is an attractive source of mesenchymal stem cells (at-MSCs), but their low osteogenic potential limits their use in bone regeneration. Adipose tissue plays a role in pro-inflammatory diseases by releasing cytokines with a catabolic effect on bone, such as tumor necrosis factor-alpha (TNF-α). Thus, we hypothesized that endogenous TNF-α could have a negative effect on at-MSC differentiation into osteoblasts. Short interfering RNAs (siRNAs) targeting TNF-α receptors (siR1, siR2, and si1R/R2) were transfected into at-MSCs, and cell differentiation was assessed by measuring the expression of bone markers, ALP activity, and mineralized matrix. Scrambled was used as Control. Knockout at-MSCs (KOR1/R2) was injected in mice calvaria defects, and bone formation was evaluated by microtomography and histological analysis. Data were compared by Kruskal–Wallis or analysis of variance (5%). The expression of bone markers confirmed that at-MSCs differentiate less than bone marrow MSCs. In silenced cells, the expression of Alp, Runx2, and Opn was generally higher compared to Control. ALP, RUNX2, and OPN were expressed at elevated levels in silenced groups, most notably at-MSCs-siR1/R2. ALP was detected at high levels in at-MSCs-siR1/R2 and in-MSCs-siR1, followed by an increase in mineralized nodules in at-MSCs-siR1/R2. As the morphometric parameters increased, the groups treated with KOR1/R2 exhibited slight bone formation near the edges of the defects. Endogenous TNF-α inhibits osteoblast differentiation and activity in at-MSCs, and its disruption increases bone formation. While opening a path of investigation, that may lead to the development of new treatments for bone regeneration using at-MSC-based therapies.     

Cytokine and nitric oxide production by Trypanosoma brucei infection in rats fed polyamine-deficient chow

Feeding polyamine-deficient chow (PDC) to rats decreases blood polyamines, increases the activity of ornithine decarboxylase as an index of polyamine production, and increases resistance to Trypanosoma brucei gambiense (Wellcome strain) (WS) infection. In this study, we investigated the influence on cytokine and nitric oxide (NO) production of feeding PDC to rats infected with WS. At 4 days postinfection with WS, serum concentration of interleukin (IL)-12, tumor necrosis factor-alpha, interferon-gamma, IL-10, and NO increased in PDC-fed rats; however, IL-12 concentration in normal chow (NC)-fed rats did not increase. In spleen cells cocultured with WS, levels of IL-12 and inducible NO synthase (NOS) mRNA expression were higher in PDC-fed rats than in NC-fed rats. Proliferation of WS in coculture with spleen cells from PDC-fed rats was inhibited, but inhibition of WS proliferation was not observed when an NOS inhibitor was added into the culture media. Ornithine decarboxylase (ODC) activity increased in NC-fed rats after WS infection, but decreased in PDC-fed rats. These results show that feeding WS-infected rats PDC influences the production of cytokines such as IL-12 and the regulation of NO and polyamine production, and also leads to an increase in resistance against WS.     

Characterization of the antitumor activities of human tumor necrosis factor-alpha and the comparison with other cytokines: induction of tumor-specific immunity

We have investigated the in vitro and in vivo antitumor activities of recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) against Meth A sarcoma. Meth A sarcoma cells were found to a) be relatively insensitive in vitro to rHuTNF-alpha, and b) express low numbers of TNF-alpha receptors. Intraperitoneally implanted Meth A sarcoma was insensitive to the antitumor effects of rHuTNF-alpha. In contrast, rHuTNF-alpha was highly efficacious against subcutaneously implanted Meth A sarcoma. Biodistribution studies with 125I- or 3H-labeled rHuTNF-alpha demonstrated that, after intravenous administration, the majority of the labeled rHuTNF-alpha localized in the kidney, lungs, and liver. Only low levels of radiolabel were found in subcutaneous Meth A implants. These results support the in vitro data on the low number of TNF-alpha receptors on Meth A sarcoma cells. The ability of rHuTNF-alpha to induce regression of established (7 days) subcutaneous Meth A implants, positively correlated with the degree of both macroscopic and microscopic tumor necrosis. In addition, recombinant human tumor necrosis factor-beta (lymphotoxin) and recombinant murine tumor necrosis factor-alpha induced similar levels of necrosis. Other lymphokines with known antitumor activities, recombinant human interferon-gamma, murine interferon-gamma, and human interleukin 1 alpha, failed to induce detectable necrosis of Meth A sarcoma. Mice which had rejected subcutaneous Meth A sarcoma implants after rHuTNF-alpha treatment and which were later challenged subcutaneously with Meth A sarcoma or other noncross-reacting chemically induced sarcomas were found to be specifically immune to Meth A sarcoma. In addition, low levels of cytotoxic antibodies reactive to Meth A sarcoma were detected in the sera of 21 of 30 Meth A immune mice. Histological evaluation of the hemorrhagic tumor necrosis induced by rHuTNF-alpha suggests that the primary lesion is vascular, possibly directly on the endothelial cells. The mechanisms involved in the generation of specific cell-mediated antitumor immunity in this model are at present unknown.     

Effect of combination of thalidomide and sulfasalazine in experimentally induced inflammatory bowel disease in rats

Thalidomide provided significant protection against tri nitro benzene sulfonic acid induced colitis. Combination therapy also reduced colonic inflammation and all the biochemical parameters (myeloperoxidase assay, malondialdehyde assay and tumor necrosis factor-alpha, estimation) were significant as compared to control as well as thalidomide alone treated group. Combination therapy showed additive effect of thalidomide which restored lipid peroxidation as well as reduced myeloperoxidase and TNF-a towards the normal levels. Morphological and histological scores were significantly reduced in combination groups. In experimental model of colitis, oral administration of thalidomide (150 mg/kg) alone as well as its combination with sulfasalazine (360 mg/kg) significantly reduced the colonic inflammation. The results indicate the additive effect of thalidomide with sulfasalazine in rat colitis model which requires further confirmation in human studies.     

Differential regulation of phospholipase A2 by cytokines inhibiting bone formation and mineralization.

Treatment of fetal rat calvarial cells with interleukin-1 alpha, tumor necrosis factor-alpha, transforming growth factor-beta 1, or group II phospholipase A2 inhibits the number of bone nodules formed in long-term cultures. These same mediators also inhibit the mineralization of fully developed bone nodules in a time and dose-dependent fashion. The pro-inflammatory cytokines interleukin-1 alpha and tumor necrosis factor-alpha cause a dose-dependent induction of rat calvarial cell phospholipase A2-II mRNA levels, suggesting that their effects on bone formation may be mediated indirectly by activation of this enzyme. In contrast, transforming growth factor-beta 1, which has more potent effects on bone formation than interleukin-1 alpha or tumor necrosis factor-alpha, suppresses basal levels of phospholipase A2-II mRNA, indicating a different mechanism of action for this cytokine.