Tumor necrosis factor alpha stimulates invasion of Src-activated intestinal cells

BACKGROUND & AIMS: Src activation is correlated with progression of colorectal cancer (CRC). CRCs accompanied by ulcerative colitis, chronic inflammation in the colon, often have elevated Src activity, and ulcerative colitis-related CRCs are more likely to become invasive, whereas Ras activation is rarely associated with this disease. The aim of this study was to investigate the effects of a proinflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), on the invasive properties of epithelial cells constitutively expressing activated Ras or Src. METHODS: A cell line derived from intestinal epithelia was transfected with a v-src- or v-H-ras-expressing vector. The effect of TNF-alpha on morphologic changes in colonies cultured in soft agar was determined. Src protein kinase activity, peroxide production, E-cadherin expression levels, and the phosphorylation status of beta-catenin and E-cadherin were determined. The invasive potential of these cells was determined by measuring cell motility and using an in vitro invasion assay. RESULTS: TNF-alpha altered the colony morphology of src-, but not ras-expressing cells. TNF-alpha increased peroxide production, leading to Src protein expression as well as Src activity in src transfectants. Activation of Src by TNF-alpha led to reduced E-cadherin levels and enhanced invasion of src transfectants. Pyrrolidine dithiocarbamate and herbimycin A inhibited these effects. CONCLUSION: These results indicate that Src kinase activation enhances the response of epithelial cells to TNF-alpha leading to increased invasion through mechanisms that involve production of reactive oxygen intermediates.     

Tumor necrosis factor alpha acts on cultured human vascular endothelial cells to increase the adhesion of pancreatic cancer cells

We studied the effect of tumor necrosis factor alpha (TNFalpha), one of the major inflammatory cytokines, on the adhesive reaction of pancreatic cancer cells to human umbilical vein endothelial cells (HUVECs) and on the hepatic metastasis of cancer cells in vivo. After TNFalpha stimulation, the expression of E-selectin, an adhesion molecule to neutrophils on HUVECs, increased. In addition, the adhesion of pancreatic cancer cells to HUVECs increased after TNFalpha stimulation, as was observed with neutrophils. The TNFalpha-induced adhesive response depended on the extent of sialyl Lewis(a) expression on cancer cells. The hepatic metastasis in vivo was often observed when cancer cells expressing a high amount of sialyl Lewis(a) were inoculated intrasplenically after increase in plasma TNFalpha concentration by lipopolysaccharide administration. Because sialyl Lewis(a) on cancer cells is a ligand for E-selectin on HUVECs, as sialyl Lewis(x) on neutrophils, TNFalpha upregulated the adhesive interaction between sialyl Lewis(a) on cancer cells and E-selectin on HUVECs. These results suggest that production of TNFalpha after surgical trauma may stimulate the hematogenic metastasis of cancer cells with a high sialyl Lewis(a) expression.     

肿瘤坏死因子α在流行性出血热发病中的作用

在选择观察的６例流行性出血热（ＥＨＦ）患者中（重型２例，中型２例，轻型２例），发现有２例重型和１例中型患者的外周血单个核细胞（ＰＢＭＣ）表达肿瘤坏死因子α（ＴＮＦα）ＴｎＲＮＡ，特别以低血压休克期表达最为明显。同时应用免疫ＰＡＰ法对ＰＢＭＣ进行染色显示，病情重伴低血压休克或有明显肾功能损害的患者ＰＢＭＣ中ＴＮＦα阳性细胞数增加。ＥＨＦ患者除单核／巨噬细胞外，部分淋巴细胞和肾小管细胞ＴＮＦα染色亦呈阳性。动态观察ＥＨＦ患者（１０例重型、１０例中型、１０例轻型，其中包含前述６例患者）血浆ＴＮＦα变化发现，血浆ＴＮＦα的水平与临床症状程度成正比，重型病例的血浆ＴＮＦα水平要高于轻型的（发热期重型ｎ＝７，３１．６３±１２．３６ｐｍｏｌ／Ｌ，ｖｓ轻型ｎ＝１０，１９．８９±５．９４ｐｍｏｌ／Ｌ，Ｐ＜０．０５），同一病例发病的不同时期，以低血压休克期升高最为明显。血浆ＴＮＦα水平与肾小球滤过功能损伤、肾近端和远端小管损伤程度密切相关。揭示ＴＶＦα可能是造成ＥＨＦ发病，特别是低血压休克和肾损害的重要介质。应用单抗等拮抗ＴＮＦα，有可能成为今后ＥＨＦ临床治疗中一个重要的措施。     

Tumor necrosis factor alpha alters follicular steroidogenesis in vitro

Preovulatory follicles from cyclic proestrous rats were incubated in vitro in M199 for up to 24 hours with various doses of human tumor necrosis factor alpha (TNF). Stepwise increases in progesterone (P) production (20-80 ng/ml/2 follicle/24 hours) were observed with 30-300 pM TNF; 3000 pM TNF reduced (p less than 0.001) P production compared to 300 pM TNF but it was still higher (p less than 0.001) than controls. Follicular androstenedione production was inhibited by low doses of TNF (30-60 pM TNF) and stimulated by 3000 pM TNF. TNF did not alter follicular estradiol (E2) production. The time course studies using 300 pM TNF revealed that follicular P production did not increase significantly until 24 hours in culture unlike LH (160 pM) which increased P by 6 hours. Preincubation of 30 pM TNF with a monoclonal antibody to human recombinant TNF alpha prevented the increase in follicular P production observed at 24 hours in TNF-treated controls. These results indicate that in vitro TNF stimulates follicular P production but only after a lag period and thus provide a basis for future studies elucidating the role of TNF in follicular development.     

Tumor necrosis factor alpha and interferon alpha in patients with myocarditis.

AIM:To elucidate the role of tumor necrosis factor alpha (TNF alpha) and interferon alpha (INF alpha) in pathogenesis of infectious-immune myocarditis (M) and myocarditic cardiosclerosis (MCS). MATERIAL AND METHODS: Patients with infectious-immune myocarditis (n=27) and myocarditic cardiosclerosis with symptoms of heart failure (n=19). Blood levels of TNF alpha and INF alpha were measured by immune enzyme analysis. RESULTS: Mean levels of INF alpha and TNF alpha in patients with M (75+/-47 and 304+/-102 rg/ml respectively) were significantly higher than in patients with MCS and healthy donors (31+/-14 and 83+/-39; 38+/-18 95+/-58 rg/ml, respectively, p<0.05). Levels of INF alpha and TNF alpha significantly differed between patients with benign and malignant course of M (99+/-46 and 354+/-100; 39+/-10 227+/-42 rg/ml, p<0.05). Phytohemagglutinine induced TNF alpha production by leucocytes in patients with malignant M (1432+/-515 rg/ml) was higher (p<0.05) while in patients with benign M (131+/-54 rg/ml) lower (p<0.01) than in healthy donors (255+/-98 rg/ml). Patients with malignant compared with those with benign course of myocarditis had lower ejection fraction (25.9+/-12.1 and 42.5+/-11,2%, respectively, p<0.003) and higher inhospital mortality (16.6 and 0%, respectively). CONCLUSION: It is most probable that factors of regulation of INF alpha and TNF alpha production occupy an import place among mechanisms of malignant transformation of myocarditis.     

Tumor necrosis factor receptor I from patients with tumor necrosis factor receptor-associated periodic syndrome interacts with wild-type tumor necrosis factor receptor I and induces ligand-independent NF-kappaB activation

OBJECTIVE: To investigate the molecular consequences of expressing mutated forms of tumor necrosis factor receptor I (TNFRI) as found in patients with TNFR-associated periodic syndrome (TRAPS). METHODS: We cloned and expressed full-length wild-type (WT) and T50K and P46L variants of TNFRI using a new tightly regulated doxycycline-dependent expression system. This system enabled the study of molecular interactions between these receptors at both physiologic and pathophysiologic levels of expression. RESULTS: We used chemical crosslinking on the cell surface to show that WT and mutant forms of TNFRI, derived from TRAPS patients, interact in the absence of TNF ligand. Doxycycline-controlled up-regulation of one TNFRI allele, either WT or mutant, caused down-regulation of the other allele, indicating dynamic control of cell surface assembly. We also demonstrated that increased expression of mutant TNFRI (T50K) was associated with a parallel increase in NF-kappaB p65 (RelA) subunit activation, which did not occur with increased expression of WT TNFRI. CONCLUSION: The T50K TRAPS-related variant is capable of sustaining inappropriate NF-kappaB activation, resulting in persistent auto-inflammation in target organs such as skin, synovial membrane, and the central nervous system. We conclude that some of the inflammatory processes seen in TRAPS do not involve direct interaction of TNF with its receptors, but that other proinflammatory mechanisms capable of up-regulating TNFRI expression may cause cellular activation through the NF-kappaB signaling pathway.     

Tumor necrosis factor alpha in patients with acute myocardial infarction

Acute myocardial infarction (AMI) is a myocardial necrosis occurring due to persistent coronary ischemia, in which inflammation plays an important role and heart failure is a common complication. The present work was undertaken to clarify the role of Tumor Necrosis Factor Alpha (TNF-alpha) in acute myocardial infarction (AMI). The study was conducted on 20 newly diagnosed AMI patients and 10 healthy age and sex matched controls. Sequential estimation of plasma TNF alpha level was carried out at admission, 24 and 48 hours post admission using ELISA. AMI patients showed a significant increase of plasma TNF-alpha level on admission, and 24 hours post admission but not after 48 hours. However, a significant increase was still seen at 48 hours post admission in patients with signs of heart failure but not in those without signs of heart failure. A significant positive correlation was found between plasma TNF-alpha level and CPK level at admission. On the other hand a significant negative correlation was found between these 2 parameters at 24 and 48 hours post admission. It is concluded that TNF-alpha may be an early marker of myocardial damage because of the early increase of its level after ischemic injury instead of being late consequence of extensive tissue necrosis. TNF-alpha level may be an important indicator of the severity of AMI and the occurrence of heart failure.     

Tumor necrosis factor alpha and glutathione interplay in chronic heart failure

The pro-inflammatory cytokine, tumor necrosis factor alpha (TNF alpha), in concert with neurohormones, contributes to chronic heart failure (CHF) progression. This implies that TNF a antagonism may constitute an important target for CHF therapy. However, clinical trials in CHF patients using compounds that trap TNF alpha, comprising infliximab, an antibody directed to TNF alpha, and etanercept, a soluble recombinant receptor of TNF alpha, gave disappointing results bringing back to light the dual, short-term beneficial and long-term harmful effect of TNF alpha. This review focuses on the dual, concentration- and time-related effects of TNF alpha, the yin and yang action of TNF alpha in cardiac ischemia/reperfusion and contraction. Importantly, the harmful effects of TNF a are related to glutathione deficiency, a common hallmark to several other chronic inflammatory diseases. Recently, in rat models of CHF, oral administration of the glutathione precursor, N-acetylcysteine (NAC), was shown to hinder pathways of TNF alpha harmful signalling and to rescue cardiac structure and function. These results suggest that glutathione deficiency in association with TNF alpha activation may play a role in the pathophysiology of CHF and that NAC may represent a potential therapy in CHF.     

Tumor necrosis factor-alpha inhibits growth factor-mediated cell proliferation through SHP-1 activation in endothelial cells

Src homology 2-containing protein-tyrosine phosphatase 1 (SHP-1) is known to regulate signal transduction through the dephosphorylation of tyrosine kinases. In this study, we addressed the role of SHP-1 under tumor necrosis factor-alpha (TNF-alpha) stimulation in endothelial cells. The addition of recombinant vascular endothelial growth factor (50 ng/mL) or epidermal growth factor (50 ng/mL) significantly increased thymidine incorporation and c-fos promoter activity, whereas TNF-alpha (5 ng/mL) attenuated these effects in human or bovine aortic endothelial cells. In bovine aortic endothelial cells, we confirmed endogenous SHP-1 expression and that TNF-alpha activated SHP-1. Importantly, overexpression of dominant-negative SHP-1 attenuated the effect of TNF-alpha on thymidine incorporation and c-fos promoter activity. In addition, TNF-alpha attenuated vascular endothelial growth factor- and epidermal growth factor-induced extracellular signal-regulated kinase phosphorylation, whereas overexpression of dominant-negative SHP-1 prevented this inhibitory effect of TNF-alpha. Taken together, our results suggested that TNF-alpha inhibited growth factor-mediated cell proliferation through SHP-1 activation.