Enzymatic degradation of tumor necrosis factor by activated human neutrophils: role of elastase

Although the role of tumor necrosis factor-alpha (TNF) as mediator of inflammation is now well established, its interactions with polymorphonuclear neutrophils (PMN) are not fully understood. Therefore, we investigated the possible hydrolytic action on TNF of intra-lysosomal enzymes released by activated PMN in the extracellular medium. We first incubated 125I radiolabeled TNF in vitro with activated PMN and by HPLC analysis, we observed a degradation process completely blocked by the previous addition of alpha 1-Antitrypsin (AT) to the incubation medium. By comparing several degradative patterns of TNF obtained with purified leukocyte proteases and supernatant of activated PMN, we identified elastase as the major enzyme involved in this catabolic process of TNF. In a second part, we determined the bioactivity of the cleavage fragments of recombinant human TNF (rhTNF) by a cytotoxicity assay. None of the fragments was found biologically active. Our results suggest that, at inflammatory sites, an enzymatic degradation of TNF may occur in the pericellular area of activated PMN. This new catabolic pathway leading to inactivation of TNF might be regarded as an effective local negative feed-back process limiting the potentially toxic effects of this cytokine.

Impaired hydroosmotic response to vasopressin of cortical collecting tubules from lithium-treated rabbits

The hydroosmotic action of [arginine]vasopressin (vasopressin, 25 microU/ml) and of 8-Br-cAMP (10(-4)M) was studied in vitro in perfused cortical collecting tubules (CCT) isolated from rabbits fed with lithium chloride for 3 weeks. Vasopressin-dependent water reabsorption was significantly inhibited by 65% although no lithium was used in the in vitro experiments. The hydroosmotic action of 8-Br-cAMP was also inhibited by previous Li treatment, but the effect was smaller in magnitude. Water intake, diuresis, and urinary osmolality were no different in the lithium-treated animals as compared with respective pretreatment values or with control animals given an equivalent amount of sodium chloride. Neither the creatinine clearance nor the maximal urinary concentrating ability were modified by lithium treatment. A mathematical model simulating water reabsorption along the CCT predicts that a 65% reduction of vasopressin-stimulated hydraulic conductivity, as observed in the Li group, may not be sufficient to prevent a complete osmotic equilibration at the end of the CCT in vivo. We conclude that: (a) in the rabbit, lithium administration induces an impairment of the hydroosmotic action of vasopressin in the CCT, which is due to an inhibition of pre- and post-cAMP events. (b) The inhibition of vasopressin action can be demonstrated in vitro at a time when no detectable impairment of the water conservation process occurs in vivo.

Intraperitoneal secretion of interleukin-6 during continuous ambulatory peritoneal dialysis

Interleukin-6 (IL-6) was determined in serum and peritoneal dialysis effluent (PDE) of patients on chronic ambulatory peritoneal dialysis (CAPD) by a biological assay measuring the proliferation of the IL-6-dependent 7TD1 cell line. Six patients free of peritonitis displayed low but significant levels of IL-6 (mean +/- 42 pg/ml) in PDE, while IL-6 was undetectable in serum. In 6 patients with staphylococcal peritonitis, a tremendous increase in PDE levels of IL-6 was noted (range: 5,832-37,491 pg/ml), while serum IL-6 remained either undetectable or on a low level except in one case. After 5 days of antibiotic treatment, IL-6 levels in PDE returned to basal values. We conclude that CAPD results in an intraperitoneal secretion of IL-6 which is markedly but transiently increased during peritonitis episodes.

[Abdominal localizations of von Recklinghausen's neurofibromatosis: apropos of a false uterine leiomyosarcoma]

This article reports the surprising history of a patient presenting a von Recklinghausen neurofibromatosis. Ten years after a full program of radio- and chemotherapy for a so-called invasive uterine leiomyosarcoma, the diagnosis of intestinal neurofibromatosis is finally established and the patient is surgically cured. The authors discuss the difficulties of the histologic diagnosis and the aid of the recent techniques of immunohistochemical markers. The second part of the article provides the actual clinical classification of the different types of neurofibromatosis with their diagnostic approach. It also offers a review of the literature concerning the intestinal location of the disease and the potential risks of cancer formation.