The effects of tumor necrosis factor (TNF) derivatives on TNF receptors

Role of TNF-α in human female reproduction

TNF-α is a highly versatile cytokine, playing an important role in both apoptosis and inflammation, which is central to reproduction. It belongs to the Th1 type of cytokines. Thus, TNF-α is a proinflammatory cytokine and is involved during follicle development and ovulation, corpus luteum formation and regression and cyclic endometrium function. It has been postulated to be detrimental to the survival of the conceptus due to apoptosis of human primary villous trophoblast cells, leading to miscarriage. However, TNF-α may have a dual role in early pregnancy. Hormonally regulated uterine TNF-α in the mother is probably essential for trophoblast cell invasion, while increased production of TNF-α by maternal macrophages may facilitate labor. The current knowledge on the role of TNF-α and its receptors in the female reproduction is described in this review.

Interpreting crosstalk between TNF-alpha and NGF: potential implications for disease

Tumour necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine, whereas nerve growth factor (NGF) is a neurotrophin that can promote neural cell survival, differentiation and maturation. However, recent papers indicate that TNF-alpha has a pivotal role in fate decisions of neural cells in normal noninflammatory conditions, whereas NGF contributes to maintenance of inflammation. Although these observations suggest a close relationship between NGF and TNF-alpha signalling, crosstalk between these factors is not fully understood. In this Opinion article, we review recent reports regarding possible crosstalk between NGF and TNF-alpha and we propose a positive-feedback loop of their expression. We discuss the possible mechanisms by which disturbance of the crosstalk could contribute to diseases such as cancer and Alzheimer's disease.

Local immunotherapy with rhTNF-alpha mutein induces strong antitumor activity without overt toxicity--a review

Tumor necrosis factor (TNF-alpha) is a cytokine possessing antitumor and immunomodulatory properties. The studies reviewed in the present paper evaluate the effect of intratumor or intraperitoneal (i.t./i.p.) injections of human recombinant TNF-alpha (rhTNF-alpha) and its derivatives (muteins V and VI) on the course of experimental tumors. The aim of local cytokine administration was to avoid or reduce the induction of undesired systemic symptoms. Although total remissions were not observed in the studies, morphological analysis of lung tissue, accepted as the toxicity index of the cytokines, showed that rhTNF-alpha produced the least side effects. Mutein V selectively binds to p55R receptor and at the same time exhibits high antitumor activity. These results confirm the usefulness of studies on the structurally altered rhTNF-alpha derivatives, produced by means of genetic engineering techniques, which bind selectively to different cellular receptors of TNF-alpha and show similar or stronger antitumor activity compared with a native molecule, without inducing undesired symptoms.

Lack of association between the Met196Arg polymorphism in the TNFR2 gene and autoimmune diseases accompanied by vasculitis including SLE in Japanese

A polymorphism in high-affinity receptor of TNF (TNFR2) gene, Met196Arg, was reported to be associated with systemic lupus erythematosus (SLE) in Japanese, whereas the association could not be found in Europeans at all and this represents an apparent discrepancy. The association, then, should be tested in other populations to clarify the possible involvement, if any, of the TNFR2 polymorphism in SLE or other related autoimmune diseases. The purposes of this study were to examine the TNFR2 polymorphism in Japanese patients with SLE and to investigate its association with other autoimmune diseases accompanied by vasculitis, mixed connective tissue disease, Buerger's disease, and Takayasu's arteritis. We found no association at all between the TNFR2 polymorphism and any autoimmune diseases including SLE in Japanese.

The antitumor effect of intraperitoneal treatment with rhTNF-alpha muteins on Ehrlich ascites tumor growth

The intraperitoneal (i.p.) treatment with recombinant human tumor necrosis factor-alpha (rhTNF-alpha) is one of the possible therapies for tumors that are confined to the abdominal cavity. Clinical trials aiming at the exploitation of the antitumor effects of rhTNF-alpha have been largely disappointing. In this model the activity of some rhTNF-alpha derivatives was studied. Ehrlich's ascites tumor (EAT) bearing Swiss albino male mice were treated i.p. three times a week with 10 micrograms/mice of rhTNF-alpha, mutein V or mutein VI for two weeks, starting on the 4th day after tumor inoculation. Control mice received PBS. The effect of the rhTNF-alpha derivatives on the course of EAT was evaluated basing on: total ascites volume (TAV); packed cell volume (PCV); total packed cell volume (TPCV); inhibitory growth rate (IGR); cellular population of EAT fluid; morphological EAT cell changes and mean survival time (MST). In the study mutein VI had only a slight effect on MST but significant on TAV- and TPCV-IGR (p < 0.001). In mice treated with rhTNF-alpha and mutein V the enhancement of MST (p < 0.01) was accompanied by TAV- and TPCV-IGR (p < 0.001). The number of EAT cells in ascites decreased after rhTNF-alpha and mutein V administration (p < 0.001). We conclude that treatment with high-dose of this modified molecule lacking the possibility of binding with p75R and not producing so intensified side effects is likely to find wider application in therapy and prevent the ascites growth just as rhTNF-alpha dosage.

The influence of recombinant human tumor necrosis factor alpha and its muteins used alone or in combination with 2-chlorodeoxyadenosine on normal and leukemic hematopoiesis in vitro

We investigated the influence of TNF alpha and its muteins III, V and VI on the colony growth of normal and CML CFU-GM cells as well as on CFU-L clonogenic blasts from AML patients in cultures in vitro. The muteins were constructed using a synthetic cDNA fragment substituting nucleotides coding for the N-terminal amino acids in the chain of native TNF alpha. We observed that TNF alpha and mutein VI inhibited the growth of colonies formed by both types of CFU-GM and CFU-L cells in a greater degree than muteins III and V. In addition, the percentage of colony growth inhibition after the use of mutein VI was the greatest. These observations were the basis for the evaluation of interaction between 2-CdA and TNF alpha and between 2-CdA and mutein VI. We have confirmed that 2-CdA used together with mutein VI acts synergistically on CFU-GM and CFU-L cells, whereas 2-CdA and TNF alpha show the additive effect.

Listeria monocytogenes infection in mice treated with pentoxifylline

The course of L. monocytogenes infection was followed in mice treated with pentoxifylline (POF), a known inhibitor of endogenous tumor necrosis factor (TNF) formation. Administration of POF caused a delay in L. monocytogenes elimination which was probably related to a reduction the listericidal activity of macrophages and to an attenuation of delayed type hypersensitivity (DTH) to Listeria antigens. In spite of this, some POF-treated mice were protected from lethal effects of virulent L. monocytogenes bacteria.