The role of tumor necrosis factor receptors in cell signaling and the significance of soluble form levels in the serum

Distinct types of tumors exhibit differential grade of inflammation and angiogenesis in mice

Inflammation, angiogenesis and cytokine production are common features of almost, if not all tumors. However, the extent of these processes induced by different types of tumors has not been evaluated. We investigated the growth pattern of the experimental metastatic tumors, B16F10 melanoma, CT26.WT colon and 4T1 mammary cells inoculated in the flank of syngeneic mice and determined the degree of inflammation, angiogenesis, and production level of pro-inflammatory and pro-angiogenic cytokines within the tumors. In addition, we have analyzed vascular changes in the interface between the tumors and the adjacent cutaneous tissue and levels of relevant pro-inflammatory and pro-angiogenic cytokines systemically. The weight of tumors 15 days post-inoculation of 10(6) cells was markedly different. Melanomas were 2 and 10-fold heavier than colon and mammary tumors, respectively. Locally, CT26.WT tumor cells induced more vessels in cutaneous tissue adjacent to the tumors but systemically, the plasma levels of VEGF were higher (approximately 2-fold) in 4T1 tumor-bearing mice compared with the other two tumors. Mammary tumors presented the most prominent inflammatory content as assessed by a range of markers (inflammatory enzymes and cytokines). The vascular index, as determined by the intra-tumor amount of hemoglobin and number of vessels in hot spot areas, was also higher (approximately 2-fold) in melanomas compared with the other two tumors. These findings showing that distinct tumor types determine differential grade of inflammation, angiogenesis and host interaction in mice may provide new insights to tailor differential therapeutic approach based on the status of tumor biomarkers.

Effect of tumour necrosis factor-alpha receptor 1 genetic deletion on carrageenan-induced acute inflammation: a comparison with etanercept

In the present study, we used tumour necrosis factor-alpha receptor 1 knock-out mice (TNF-alphaR1KO) to evaluate an in vivo role of TNF-alphaR1 on the pathogenesis of inflammatory diseases. We used a murine model of carrageenan-induced acute inflammation (pleurisy), a preclinical model of airway inflammation. The data proved that TNF-alphaR1KO were resistant to carrageenan-induced acute inflammation compared with TNF-alpha wild-type mice. TNF-alphaR1KO showed a significant reduction in accumulation of pleural exudate and in the number of inflammatory cells, in lung infiltration of polymorphonuclear leucocytes and lipid peroxidation and showed a decreased production of nitrite/nitrate in pleural exudates. Furthermore, the intensity and degree of the adhesion molecule intercellular adhesion molecule-1 and P-selectin, Fas ligand (FasL), inducible nitric oxide sythase and nitrotyrosine determined by immunohistochemical analysis were reduced markedly in lung tissues from TNF-alphaR1KO at 4 h and 24 h after carrageenan injection. Moreover, TNF-alpha and interleukin-1beta concentrations were reduced in inflamed areas and in pleural exudates from TNF-alphaR1KO. To support the results generated using pleural inflammation, carrageenan-induced paw oedema models were also performed. In order to elucidate whether the observed anti-inflammatory effects were related to the inhibition of TNF-alpha, we also investigated the effect of etanercept, a TNF-alpha soluble receptor construct, on carrageenan-induced pleurisy. The treatment with etanercept (5 mg/kg subcutaneously 2 h before the carrageenan injection) reduces markedly both laboratory and histological signs of carrageenan-induced pleurisy. Our results showed that administration of etanercept resulted in the same outcome as that of deletion of the TNF-alphaR1 receptor, adding a new insight to TNF-alpha as an excellent target by therapeutic applications.

Role of TNF-alpha in ileum tight junction alteration in mouse model of restraint stress

Restraint stress induces permeability changes in the small intestine, but little is known about the role of tumor necrosis factor (TNF)-alpha in the defects of the TJ function. In the present study, we used tumor necrosis factor-R1 knockout mice (TNF-alpha-R1KO) to understand the roles of TNF-alpha on ileum altered permeability function in models of immobilization stress. The genetic TNF-alpha inhibition significantly reduced the degree of 1) TNF-alpha production in ileum tissues; 2) the alteration of zonula occludens-1 (ZO-1), claudin-2, claudin-4, claudin-5, and beta-catenin (immunohistochemistry); and 3) apoptosis (TUNEL staining, Bax, Bcl-2 expression). Taken together, our results demonstrate that inhibition of TNF-alpha reduces the tight junction permeability in the ileum tissues associated with immobilization stress, suggesting a possible role of TNF-alpha on ileum barrier dysfunction.

Role of TNF-alpha in lung tight junction alteration in mouse model of acute lung inflammation

In the present study, we used tumor necrosis factor-R1 knock out mice (TNF-αR1KO) to understand the roles of TNF-α on epithelial function in models of carrageenan-induced acute lung inflammation. In order to elucidate whether the observed anti-inflammatory status is related to the inhibition of TNF-α, we also investigated the effect of etanercept, a TNF-α soluble receptor construct, on lung TJ function. Pharmacological and genetic TNF-α inhibition significantly reduced the degree of (1) TNF-α production in pleural exudates and in the lung tissues, (2) the inflammatory cell infiltration in the pleural cavity as well as in the lung tissues (evaluated by MPO activity), (3) the alteration of ZO-1, Claudin-2, Claudin-4, Claudin-5 and β-catenin (immunohistochemistry) and (4) apoptosis (TUNEL staining, Bax, Bcl-2 expression). Taken together, our results demonstrate that inhibition of TNF-α reduces the tight junction permeability in the lung tissues associated with acute lung inflammation, suggesting a possible role of TNF-α on lung barrier dysfunction.

Soluble tumor necrosis factor alpha receptors (sTNF-Rs) in HIV-1-infected intravenous drug users: change in circulating sTNF-R type II level and survival for AIDS patients

This study in intravenous drug users (IVDUs) investigated differences in serum soluble tumor necrosis factor types I and II (sTNFR-I and II) concentrations in HIV-1-infected IVDUs and controls. This study also investigated whether changes of sTNFRs concentration affect the risk of death among patients with AIDS. A cross-sectional study of 54 subjects with AIDS, 47 HIV-seropositive IVDUs, 47 HIV-seronegative IVDUs, and 21 healthy subjects showed that sTNFRs concentration increases from healthy controls to AIDS patients through HIV-seronegative and HIV-seropositive subjects (p < 0.01). sTNFR-I concentration, however, was shown to be similar in HIV-seronegative IVDUs and healthy controls. In the longitudinal study, serum concentration of sTNFRs was determined near AIDS diagnosis in 21 IVDUs and 1 year later (start for the survival study). Cox proportional hazards regression was performed to assess the prognostic value of percent change of sTNFR level alone and in combination with T lymphocyte subsets, HIV-p24 antigenemia and opportunistic infections for death within 240 days. Uni- and multivariate Cox modelling for dichotomised variables according to its median showed an increase of sTNFR-II by at least 30% to be single significant predictor of death: crude relative risk 3.69, p = 0.03; adjusted relative risk 5.67, p = 0.02. Mean survival was 126 days in 11 patients whose sTNFR-II level increased by at least 30%, and 176 days in 10 patients with less change in sTNFR-II (p = 0.02).

CONCLUSIONS

sTNFRs concentration is higher in IVDUs than in healthy controls and is highest in AIDS patients. Survival of patients with AIDS is associated with variation in the concentration of sTNFR-II.

Suppressed alloantigen presentation, increased TNF-alpha, IL-1, IL-1Ra, IL-10, and modulation of TNF-R in UV-irradiated human skin

Cytokines induced in skin by ultraviolet radiation cause local and systemic immunosuppression. Tumor necrosis factor alpha, interleukin-1, and interleukin-10 are key mediators in the mouse, but less is known about cytokine synthesis and function in ultraviolet-irradiated human skin. We exposed human skin to 3 minimal erythema doses of solar-simulated radiation and raised suction blisters at intervals to 72 h. Alloantigen presentation was suppressed in a mixed epidermal cell-lymphocyte reaction by 69% from 4 to 15 h post-solar-simulated radiation, but recovered to control values by 24 h. Tumor necrosis factor alpha was raised at 4 h after solar-simulated radiation, reached a maximum 8-fold increase at 15 h, then rapidly declined to control values. Interleukin-1alpha and interleukin-1beta were first increased at 15 h, and remained raised to 72 h, although interleukin-1beta declined from its 15 h maximum. Interleukin-10 increased a maximum 2-fold between 15 and 24 h, coincident with recovery of mixed epidermal cell-lymphocyte reaction responses and downregulation of tumor necrosis factor alpha and interleukin-1beta. Solar-simulated radiation differentially affected soluble tumor necrosis factor alpha receptors; soluble tumor necrosis factor-RI was suppressed 33% at 8-15 h whereas soluble tumor necrosis factor-RII increased 2-fold from 15 to 48 h. Interleukin-1 receptor antagonist was raised at all times post-irradiation. Interleukin-12 was not detectable in control or irradiated skin. These kinetics suggest the tumor necrosis factor alpha network has primary importance in ultraviolet-damaged human skin. The small increase in interleukin-10 implies that 3 minimal erythema doses of solar-simulated radiation is the threshold dose for its induction and local, rather than systemic, functions for interleukin-10 in immunosuppression and regulation of other cytokines.

Serum levels of intercellular adhesion molecule 1 (ICAM-1) in patients with colorectal cancer: inhibitory effect on cytotoxicity

A positive correlation between the level of ICAM-1 in serum and the stage of neoplastic processes has been demonstrated. We studied ICAM-1 serum concentration in 27 colorectal cancer patients and investigated the effect of this molecule on cellular aggregation and toxicity. ICAM-1 serum concentration in the group of patients was significantly higher (P < 0.01) than in normal controls and was related to tumour stage. Patient sera inhibited both the formation of cellular aggregates and the percentage of specific lysis, the effect being lost when the serum was depleted of ICAM-1. These results suggest that the release of soluble ICAM-1 may represent a mechanism of tumour escape.

Polymorphisms of tumor necrosis factor receptor 2 are not associated with insulin-dependent diabetes mellitus or Graves' disease

Insulin-dependent diabetes mellitus (IDDM) and Graves' disease (GD) are autoimmune endocrinopathies and associated with distinct HLA-DR and -DQ alleles as well as several tumor necrosis factor alpha (TNF-alpha) and beta (TNF-beta) alleles. TNF-alpha and TNF-beta interact with TNF receptor (TNF-R), of which two subtypes have been described: TNF-R1 and TNF-R2. We investigated TNF-R2 alleles in 90 patients with IDDM, 101 with GD and 70 healthy controls. Genomic DNA was amplified with specific flanking primers for the untranslated 3' region of TNF-R2. SSCP analysis revealed two alleles by different fragment patterns: TNF-R2*1 and TNF-R2*2. Patients with IDDM or Graves' disease and controls did not differ significantly: TNF-R2*1/*1:IDDM(8%)/GD(2%)/KO(4%); TNF-R2*2/*2:IDDM(34%)/GD(48%)/KO(42%), heterozygosity TNF-R2*1/*2:IDDM(58%)/GD(50%)/KO(54%) (IDDM vs KO: P=0.46, chi2=1.57; GD vs KO: P=0.59, chi2=1.05). In conclusion, the studied polymorphism of TNF-R2 was associated with neither IDDM nor GD in a German population.