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      TNF-α is a critical negative regulator of type 1 immune activation during intracellular bacterial infection

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          Most cited references 47

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          Tuberculosis associated with infliximab, a tumor necrosis factor alpha-neutralizing agent.

          Infliximab is a humanized antibody against tumor necrosis factor alpha (TNF-alpha) that is used in the treatment of Crohn's disease and rheumatoid arthritis. Approximately 147,000 patients throughout the world have received infliximab. Excess TNF-alpha in association with tuberculosis may cause weight loss and night sweats, yet in animal models it has a protective role in the host response to tuberculosis. There is no direct evidence of a protective role of TNF-alpha in patients with tuberculosis. We analyzed all reports of tuberculosis after infliximab therapy that had been received as of May 29, 2001, through the MedWatch spontaneous reporting system of the Food and Drug Administration. There were 70 reported cases of tuberculosis after treatment with infliximab, for a median of 12 weeks. In 48 patients, tuberculosis developed after three or fewer infusions. Forty of the patients had extrapulmonary disease (17 had disseminated disease, 11 lymph node disease, 4 peritoneal disease, 2 pleural disease, and 1 each meningeal, enteric, paravertebral, bone, genital, and bladder disease). The diagnosis was confirmed by a biopsy in 33 patients. Of the 70 reports, 64 were from countries with a low incidence of tuberculosis. The reported frequency of tuberculosis in association with infliximab therapy was much higher than the reported frequency of other opportunistic infections associated with this drug. In addition, the rate of reported cases of tuberculosis among patients treated with infliximab was higher than the available background rates. Active tuberculosis may develop soon after the initiation of treatment with infliximab. Before prescribing the drug, physicians should screen patients for latent tuberculosis infection or disease.
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            Mice deficient for the 55 kd tumor necrosis factor receptor are resistant to endotoxic shock, yet succumb to L. monocytogenes infection.

            The multiple biological activities of tumor necrosis factor (TNF) are mediated by two distinct cell surface receptors of 55 kd (TNFRp55) and 75 kd (TNFRp75). Using gene targeting, we generated a TNFRp55-deficient mouse strain. Cells from TNFRp55-/-mutant mice lack expression of TNFRp55 but display normal numbers of high affinity TNFRp75 molecules. Thymocyte development and lymphocyte populations are unaltered, and clonal deletion of potentially self-reactive T cells is not impaired. However, TNF signaling is largely abolished, as judged by the failure of TNF to induce NF-kappa B in T lymphocytes from TNFRp55-deficient mice. The loss of TNFRp55 function renders mice resistant to lethal dosages of either lipopolysaccharides or S. aureus enterotoxin B. In contrast, TNFRp55-deficient mice are severely impaired to clear L. monocytogenes and readily succumb to infection. Thus, the 55 kd TNFR plays a decisive role in the host's defense against microorganisms and their pathogenic factors.
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              Characterization of tumor necrosis factor-deficient mice.

              Although tumor necrosis factor (TNF) initially came to prominence because of its anti-tumor activity, most attention is now focused on its proinflammatory actions. TNF appears to play a critical role in both early and late events involved in inflammation, from localizing the noxious agent and amplifying the cellular and mediator responses at the local site and systemically, to editing (e.g., apoptosis) injured cells or effete immune cells and repairing inflammatory damage. We have generated mice deficient in TNF (TNF-/- mice) and have begun to examine the multiple functions attributed to TNF. TNF-/- mice develop normally and have no gross structural or morphological abnormalities. As predicted, they are highly susceptible to challenge with an infectious agent (Candida albicans), are resistant to the lethality of minute doses of lipopolysaccharide (LPS) following D-galactosamine treatment, have a deficiency in granuloma development, and do not form germinal centers after immunization. Phagocytic activity of macrophages appears relatively normal, as do T cell functions, as measured by proliferation, cytokine release, and cytotoxicity. B cell response to thymus-independent antigens is normal, but the Ig response to thymus-dependent antigen is reduced. Surprisingly, cytokine production induced by LPS appears essentially intact, with the exception of reduced colony-stimulating factor activity. Other unexpected findings coming from our initial analysis are as follows. (i) TNF has low toxicity in TNF-/- mice. (ii) TNF-/- mice show an anomalous late response to heat-killed Corynebacterium parvum. In contrast to the prompt response (granuloma formation, hepatosplenomegaly) and subsequent resolution phase in C. parvum-injected TNF+/+ mice, similarly treated TNF-/- mice show little or no initial response, but then develop a vigorous, disorganized inflammatory response leading to death. These results suggest that TNF has an essential homeostatic role in limiting the extent and duration of an inflammatory process-i.e., an anti-inflammatory function. (iii) In contrast to the expectation that TNF+/+ mice and TNF+/- mice would have identical phenotypes, TNF+/- mice showed increased susceptibility to high-dose LPS lethality, increased susceptibility to Candida challenge, and delayed resolution of the C. parvum-induced inflammatory process, indicating a strong gene dose requirement for different actions of TNF.
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                Author and article information

                Journal
                Journal of Clinical Investigation
                J. Clin. Invest.
                American Society for Clinical Investigation
                0021-9738
                February 1 2004
                February 1 2004
                : 113
                : 3
                : 401-413
                Article
                10.1172/JCI200418991
                © 2004
                Product
                Self URI (article page): http://www.jci.org/articles/view/18991

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