TNF-α and Chronic Fatigue Syndrome

Based upon the clinical presentation of chronic fatigue syndrome (CFS), we hypothesized that proinflammatory cytokines may play a role in the pathogenesis of the disease. We therefore undertook a retrospective cross-sectional study to examine the role of TNF- in patients with CFS. Our results suggest a significant increase serum TNF- in patients with CFS (P < 0.0001) compared to non-CFS controls. This study supports the further examination of the role of proinflammatory mediators in CFS. Furthermore, the clinical testing of TNF- blockers and other antiinflammatory agents for the treatment of this disease is warranted.     

血清TNF-α RIA及其临床意义

肿癌坏死因子α(Tumour necrosis factoralpha,TNF-α)是由单核巨噬细胞所产生的一种多肽，不仅具有使肿癌坏死退化的作用且参与抗感染、凝血、发热、休克、多器官功能衰竭、恶病质等多种病理生理过程，对白细胞、内皮细胞等各种细胞的功能以及某些细胞的生长与分化均有激素样作用。本文报告了用放免法测定的正常人及病人血清TNF4α值，并对其意义进行了探讨。     

TNF-α and neuropathic pain - a review

Tumor necrosis factor alpha (TNF-α) was discovered more than a century ago, and its known roles have extended from within the immune system to include a neuro-inflammatory domain in the nervous system. Neuropathic pain is a recognized type of pathological pain where nociceptive responses persist beyond the resolution of damage to the nerve or its surrounding tissue. Very often, neuropathic pain is disproportionately enhanced in intensity (hyperalgesia) or altered in modality (hyperpathia or allodynia) in relation to the stimuli. At time of this writing, there is as yet no common consensus about the etiology of neuropathic pain - possible mechanisms can be categorized into peripheral sensitization and central sensitization of the nervous system in response to the nociceptive stimuli. Animal models of neuropathic pain based on various types of nerve injuries (peripheral versus spinal nerve, ligation versus chronic constrictive injury) have persistently implicated a pivotal role for TNF-α at both peripheral and central levels of sensitization. Despite a lack of success in clinical trials of anti-TNF-α therapy in alleviating the sciatic type of neuropathic pain, the intricate link of TNF-α with other neuro-inflammatory signaling systems (e.g., chemokines and p38 MAPK) has indeed inspired a systems approach perspective for future drug development in treating neuropathic pain.     

Complications of TNF-α antagonists and iron homeostasis

TNF-α is a central regulator of inflammation and its blockade downregulates other pro-inflammatory cytokines, chemokines, and growth factors. Subsequently, TNF-α antagonists are currently used in treatment regimens directed toward several inflammatory diseases. Despite a beneficial effect, the use of TNF-α antagonists is associated with an increased risk for infections and neoplasms; the basis for these complications is unclear. This cytokine also participates in iron homeostasis and the sequestration of this metal, mediated by TNF-α, is considered protective. We hypothesize that treatment with TNF-α antagonists predisposes the patient to infections and neoplasms by reversing the sequestration of host iron mediated by the cytokine and increasing available concentrations of this metal. It is recommended that patients who are to receive TNF-α antagonists be tested for iron overload and the use of these agents in those individuals with excess iron should be reconsidered. Furthermore, it is predicted that alternative attempts to treat inflammatory diseases by blocking other pivotal cytokines that also participate in iron homeostasis (e.g. IFN-γ, IL-1, and IL-6) will similarly be associated with infections and neoplastic complications.     

Placental TNF-α signaling in illness-induced complications of pregnancy

Maternal infections are implicated in a variety of complications during pregnancy, including pregnancy loss, prematurity, and increased risk of neurodevelopmental disorders in the child. Here, we show in mice that even mild innate immune activation by low-dose lipopolysaccharide in early pregnancy causes hemorrhages in the placenta and increases the risk of pregnancy loss. Surviving fetuses exhibit hypoxia in the brain and impaired fetal neurogenesis. Maternal Toll-like receptor 4 signaling is a critical mediator of this process, and its activation is accompanied by elevated proinflammatory cytokines in the placenta. We evaluated the role of tumor necrosis factor-α (TNF-α) signaling and show that TNF receptor 1 (TNFR1) is necessary for the illness-induced placental pathology, accompanying fetal hypoxia, and neuroproliferative defects in the fetal brain. We also show that placental TNFR1 in the absence of maternal TNFR1 is sufficient for placental pathology to develop and that a clinically relevant TNF-α antagonist prevents placental pathology and fetal loss. Our observations suggest that the placenta is highly sensitive to proinflammatory signaling in early pregnancy and that TNF-α is an effective target for preventing illness-related placental defects and related risks to the fetus and fetal brain development.     

早期自然流产患者TNF-α mRNA的异常表达

目的探讨自然流产患者外周血单个核细胞内肿瘤坏死因子-α mRNA的异常表达.方法采用半定量逆转录-聚合酶链反应(RT-PCR)技术,检测30例早期自然流产患者、25例正常妊娠妇女、25例正常未妊娠妇女外周血单个核细胞内TNF-α mRNA.结果早期自然流产患者、正常妊娠妇女、正常未妊娠妇女三组研究对象外周血单个核细胞表达TNF-α mRNA相对含量分别为20.1±9.4%、68.6±14.1%、97.0±11.6%.结论早期自然流产患者外周血单个核细胞TNF-α mRNA表达水平显著下降,提示流产过程中能分泌TNF-α的单个核细胞可能聚集于母胎界面,TNF-α可能在母胎界面局部发挥作用并导致流产.     

Morphine Stimulates Mesangial Cell TNF-α and Nitrite Production

Background: Intravenous opiate abusers are susceptible to develop heroin and HIV-associated nephropathies; however, the role of opiates in the development of these kidney lesions is not clear. Patients with opiate addiction are prone to recurrent infections. Methods: The effect of morphine was studied on the generation of TNF- with or without LPS (lipopolysaccharide) by cultured mouse mesangial cells. In addition, the effect of morphine was evaluated on mesangial cell nitrite production. To evaluate the role of opiate receptors, we studied the effect of naloxone and naltrexone on mesangial cell TNF- and nitrite production. To determine the role of TNF- on mesangial cell nitrite production, we examined the effect of anti-TNF- antibody on morphine-induced nitrite production. Assay of TNF- and nitrite production was carried by ELISA and Griess method respectively. Results: Morphine alone did not enhance the generation of TNF- by mesangial cells, however, an enhanced (P < 0.001) TNF- production was observed when mesangial cells were first treated with morphine for 18 h and then activated further with LPS. Maximum release of TNF- was seen at a concentration of 10^–12 M of morphine. Opiate receptor antagonists (naloxone and naltrexone) inhibited the effect of morphine. Morphine also amplified (P < 0.0002) the effect of LPS on mesangial cell nitrite production. Anti-TNF- antibody attenuated morphine induced nitrite generation. Conclusion: We conclude that morphine stimulates the generation of TNF- by LPS-activated mesangial cells. This effect of morphine seems to be opiate receptor mediated and has a downstream effect in the form of mesangial cell nitrite generation. The present in vitro study provides the basis for a hypothesis that morphine may be playing a role in the development of heroin and HIV-associated nephropathies.     

TNF-α and sICAM-1 in intracranial aneurismal rupture

Introduction  Subarachnoidal hemorrhage (SAH) occurring after aneurismal rupture produces an inflammatory response in the cerebral circulation. Tumor necrosis factor (TNF)-α is a major cytokine in this process. Adhesion molecules provide information on inflammatory reactions taking place in the walls of blood vessels. Clinical evidence suggests a role of soluble intercellular adhesion molecule (sICAM)-1 in early hemorrhagic events. This study aimed to evaluate the implementation of early TNF-α and sICAM-1 serum measurement for the prognosis of patient outcome after intracranial aneurismal rupture. Materials and Methods  The study consisted of 27 patients with a diagnosis of intracranial aneurysm. SAH was evaluated on admission according to the Fisher scale, patients’ consciousness with the Glasgow Coma Scale, clinical grading with the Hunt and Hess scale, and clinical outcome with the Glasgow Outcome Scale (GOS). Blood samples were drawn within 72 h after arrival at the emergency room. Serum concentrations of TNF-α and sICAM-1 were assayed with the ELISA method. Results  The initial serum TNF-α concentration in the aneurismal patients was low and did not correlate with radiological and clinical scores. The serum sICAM-1 level positively correlated with the severity of bleeding assessed by the Fisher scale and negatively with the patient’s scoring in the GOS. Conclusions  This study demonstrated the absence of a systemic TNF-α-mediated inflammatory response at the onset of subarachnoid hemorrhage. Early measurement of serum sICAM-1 levels offers a potential prognostic value in the assessment of patients’ outcome after brain aneurismal rupture.     

Effects of pyridinyl imidazole compounds on murine TNF-α production

The effects of SK&F 86002 and other pyridinyl imidazole compounds on murine cytokine production were investigated.In vitro, SK&F 86002 inhibited LPS stimulated TNF-α production by the RAW 264.7 cell line and by oil elicited peritoneal macrophages with an IC₅₀ of 5μM. In general, the activity was reflective of previous results obtained with human monocytes as SK&F 86002 and its analogs demonstrated identical rank order potency for TNF-α inhibition in both species. These compounds also inhibited TNF-αin vivo in a murine model of endotoxin shock. Following oral administration, SK&F 86002 and its analogs reduced serum TNF-α levels by >80% and afforded 100% protection from lethality. In contrast, tenidap, a novel anti-inflammatory drug, had minimal to no effect on murine TNF-α production in the same assays. These data further extend the pharmacological profile of the pyridinyl imidazoles by demonstrating that these compounds potently inhibit murine TNF-α production bothin vitro andin vivo.     

Does TNF-α directly increase endothelial cell monolayer permeability?

The effects of dexamethasone (DEX) and ϖ methyl ester (l-NAME) on the tumour necrosis factor-α (TNF-α)-induced increase in permeability of human umbilical vein endothelial cell (HUVEC) monolayer to [¹²⁵I] labelled bovine serum albumin (BSA) were examined. Preincubation of HUVEC monolayers with DEX (1μM, 2 h) completely abolished the effect of TNF-α (5 ng/ml, 18 h). Administration of DEX 2 h after TNF-α also reduced the effect of TNF-α, whilel-NAME (5 ng/ml, 1 mM, 18 h) had no significant effect.

The observed inhibition of the TNF-α-induced permeability increase on preincubation with DEX would suggest a role for nitric oxide (NO) in mediating the permeability response. However, this is not confirmed by the experiments withl-NAME. The inhibition caused by DEX administered after TNF-α would suggest alternative mechanisms by which DEX may be acting in addition to inhibition of NO synthase induction.

     

Effects of pyridinyl imidazole compounds on murine TNF-α production

The effects of SK&F 86002 and other pyridinyl imidazole compounds on murine cytokine production were investigated.In vitro, SK&F 86002 inhibited LPS stimulated TNF- production by the RAW 264.7 cell line and by oil elicited peritoneal macrophages with an IC₅₀ of 5M. In general, the activity was reflective of previous results obtained with human monocytes as SK&F 86002 and its analogs demonstrated identical rank order potency for TNF- inhibition in both species. These compounds also inhibited TNF-in vivo in a murine model of endotoxin shock. Following oral administration, SK&F 86002 and its analogs reduced serum TNF- levels by >80% and afforded 100% protection from lethality. In contrast, tenidap, a novel anti-inflammatory drug, had minimal to no effect on murine TNF- production in the same assays. These data further extend the pharmacological profile of the pyridinyl imidazoles by demonstrating that these compounds potently inhibit murine TNF- production bothin vitro andin vivo.     

IL-33 regulates TNF-α dependent effects in synovial fibroblasts

The recently described IL-33 acts as a pro-inflammatory cytokine, inducing the expression of multiple responses in the target cells. Although a nuclear localization of IL-33 has been described, its exact functional relevance is presently unknown. The present study was conducted to analyze the effects of IL-33 on the TNF-α induced synthesis of the pro-inflammatory mediators IL-6, IL-8, and monocyte chemotactic protein-1 (MCP-1) and the pro-destructive molecules matrix metalloproteinase-1 (MMP-1), MMP-3, and TIMP-1 of rheumatoid arthritis synovial fibroblast (RA-SFs) using RNA overexpression and silencing. TNF-α significantly induced IL-33 mRNA expression and protein synthesis in RA-SFs. TNF-α-induced IL-33 protein expression was mediated via p38 signaling. Immunohistochemistry for IL-33 clearly showed that nuclear translocation of IL-33 was induced in TNF-α stimulated RA-SFs. IL-33 overexpression enhanced TNF-α-induced pro-inflammatory and pro-destructive functions in RA-SFs. IL-33 silencing significantly downregulated TNF-α-induced pro-inflammatory functions, whereas TNF-α-induced pro-destructive functions were less influenced by IL-33 silencing. This study identifies IL-33 as a critical regulator/enhancer of TNF-α-induced functions in RA-SFs, pointing to a central role of this cytokine in the perpetuation of pro-inflammatory and pro-destructive processes in rheumatoid arthritis (RA) and other inflammatory and degenerative diseases.     

The role of TNF-α in regulating ketamine-induced hippocampal neurotoxicity

Introduction

Ketamine is commonly used in pediatric anesthesia but recent studies have shown that it could induce neurotoxicity in the developing brain. The inflammatory cytokine, tumor necrosis factor α (TNF-α) is involved in the pathogenesis of various types of neurodegenerations. In the present study, we examined whether TNF-α may regulate ketamine-induced neurotoxicity in the hippocampus of neonatal mouse.

Material and methods

The in vitro organotypic culture of hippocampal slices was used to investigate the gain-of-function and loss-of-function effect of TNF-α modulation on ketamine-induced hippocampal neurotoxicity. Also, western blotting analysis was used to examine the relative pathways associated with TNF-α modulation. In the in vivo Morris water maze test, TNF-α was genetically silenced to see if memory function was improved after anesthesia-induced memory impairment.

Results

In in vitro experiments, adding TNF-α enhanced (112.99 ±5.4%, p = 0.015), whereas knocking down TNF-α ameliorated (46.8 ±11.6%, p = 0.003) ketamine-induced apoptosis in hippocampal CA1 neurons in the organotypic culture. Western blotting showed that addition of TNF-α reduced (67.1 ±3.7%, p = 0.022), whereas downregulation of TNF-α increased (126.87 ±8.5%, p = 0.004) the phosphorylation of PKC-ERK pathway in ketamine-treated hippocampus. In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.

Conclusions

Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity. This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.     

TNF-α signalling and inflammation: interactions between old acquaintances

Introduction

Inflammation is a very important part of innate immunity and is regulated in many steps. One such regulating step is the cytokine network, where tumor necrosis factor α (TNF-α) plays one of the most important roles.

Methods

A PubMed and Web of Science databases search was performed for studies providing evidences on the role of TNF-α in inflammation, apoptosis, and cancer.

Results and Conclusion

This review concisely summarizes the role of this pro-inflammatory cytokine during inflammation. It is focused mainly on TNF-α intracellular signaling and its influence on the typical inflammatory features in the organism. Being one of the most important pro-inflammatory cytokines, TNF-α participates in vasodilatation and edema formation, and leukocyte adhesion to epithelium through expression of adhesion molecules; it regulates blood coagulation, contributes to oxidative stress in sites of inflammation, and indirectly induces fever. The connection between TNF-α and cancer is mentioned as well.     

Impact of TNF-α and LTα gene polymorphisms on genetic susceptibility in Indian SLE patients

The promoter polymorphisms of tumour necrosis factor-α (TNF-α) and intronic Lymphotoxin-α (LTα) have been implicated as genetic risk factors for systemic lupus erythematosus (SLE) in various ethnic groups. The aim of this study was to investigate an impact of TNF-α (?308G/A; 238G/A) and LTα (+252A/G) gene polymorphisms in disease susceptibility among Indian 200 SLE patients along with 201 healthy controls. The gene polymorphisms were studied by using direct DNA sequencing and Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) methods. Serum levels were measured by multiplex assay. Allelic frequencies of TNF-α ?308A (OR = 2.3, p = 0.0001, Pc = 0.0003) and LTα +252G (OR = 2.1, p < 0.0001, Pc < 0.001) were significantly higher in SLE patients. Frequency of haplotype-AGG was found to be higher in patients than controls (OR = 12.2, p = 0.0050). Serum levels of TNF-α and LTα also were found to be significantly higher in patients showing variant alleles. TNF-α ?308G/A + A/A genotypes (p < 0.01) and LTα +252 A/G + G/G genotypes (p < 0.02) were significantly associated with renal disorders and haematological manifestations. SLE patients with ?308G/A + A/A genotypes showed higher prevalence of anti-dsDNA antibodies (OR = 3.9, p = 0.0014, Pc = 0.0098) and anti-Sm antibodies (OR = 4.1, p = 0.0002, Pc = 0.0014). The present study suggests TNF-α ?308A and LTα +252G as risk alleles for disease susceptibility associated with higher serum levels of TNF-α and LTα and concomitant discrete clinical features among Indian SLE patients.     

CDR3突变提高抗TNF-α Fab段的亲和力

目的通过抗体库技术在CDR3区引入限定性突变以提高抗TNF-α抗体Fab的亲和力。方法首先合成含CDR3区突变的寡核苷酸,限定突变率以保持50%~70%的亲本序列,通过重叠延伸PCR的方法引入突变,构建突变库,再以硫氰酸铵溶液作洗涤液,筛选亲和力得到提高的特异性克隆,用非竞争性ELISA法测定亲和常数。结果从轻链突变库中筛选得到1个活性提高的特异性克隆K8,在第93位发生N→R突变,其亲和常数为2.8×108L/mol,较亲本抗体(0.1×108L/mol)提高了近28倍;从重链突变库中筛选得到多个活性增高的克隆,部分克隆测序显示96、97和100d位置发生R→K、Y→Q、M→L突变的几率最高,且对亲和力提高贡献大。测定了10个变种的亲和常数,分别为0.2×108、0.22×108、1.8×108、3.2×108、3.3×108、3.5×108、3.7×108、4.0×108、6.3×108和6.5×108L/mol,最大的提高了近65倍。结论CDR3区的限定性突变可显著提高抗体亲和力。     

Cytotoxic reaction and TNF-α response of macrophages to polyurethane particles

Their unique mechanical and biological properties make polyurethanes (PUs) ideal materials for many implantable devices. However, uncertain long-term biostability in the human physiological environment limits their extensive clinical applications. Chronic inflammatory response associated with macrophage activation has been suggested as a prime factor; although the mechanism of macrophage activation in response to biomaterial surfaces and debris is still unknown. The overall objective of this work was to study the response of macrophages to PU materials in vitro by measuring cell viability and activity. The studies were carried out using phagocytozable-size PU particles from three types of commercially-available PUs: Pellethane^® 2363 80ABA (PL); Tecothane^® TT2065 (TC65); and Tecothane^® TT2085 (TC85). These polymers posess the same generic composition but differ in the length of hard and soft segments, as revealed by the FTIR and NMR studies. The results showed that PU particles affected both viability and activity of J774 macrophages. The percentage of mortality ranged from 1 to 15% with 10-100 μg ml^-1 of particles after 24 and 48 h incubation. These three types of particles induced different mortality on the macrophages. Specifically, the mortality with PL particles was 1-4% (p > 0.05), while the mortality with TC85 particles was 2-10% (p < 0.05) and 4-15% with TC65 (p < 0.05). Conversely, these particles also affected cell proliferation. Cell numbers increased by 132 and 167% after 24 and 48 h incubation, respectively, without particles, whereas the cell numbers increased only 46 and 78% with TC65, 66 and 105% with TC85, and 67 and 110% with PL in the presence of 100 μg ml^-1 of particles for the respective incubation times. PU particles also increased TNF-α release from macrophage. After having been incubated for 24 h with 100 μg ml^-1 particles of TC65, TC85, and PL, macrophages release TNF-α 7.4, 5.2, and 4.1 times more than the control. In conclusion, PU particles had cytotoxic effects on J774 macrophage at high concentrations. The order of macrophage response for three types of particles was TC65 > TC85 > PL. PU particles' effect on macrophage viability and activity depends on the concentration of particles and their chemical composition, especially on the ratio of hard to soft segments.