Strategies targeting tumor necrosis factor in Crohn's disease

Tumor necrosis factor plays an important role in mediating the inflammation of Crohn's disease. Strategies aimed at reducing tumor necrosis factor in patients with Crohn's disease include the mouse/human chimeric monoclonal antibody infliximab, the humanized monoclonal antibody CDP571, the human recombinant tumor necrosis factor receptor fusion protein etanercept, and the small molecule thalidomide. Infliximab is effective for treating active Crohn's disease, maintaining remission, and closing fistulas. Side effects occurring in patients treated with infliximab include human anti-chimeric antibodies, infusion reactions, formation of autoantibodies, and rarely drug induced lupus. CDP571 is effective for treating active Crohn's disease, steroid sparing, and possibly for closing fistulas and maintaining remission. Side effects occurring in patients treated with CDP571 include anti-idiotype antibodies, infusion reactions, and formation of autoantibodies. Pilot studies have suggested that etanercept and thalidomide may also be beneficial. Anti-tumor necrosis factor therapies are effective for the treatment for Crohn's disease.     

Lessons for lupus from tumour necrosis factor blockade

Systemic lupus erythematosus (SLE) is a systemic non-organ specific autoimmune disease associated with multiple autoantibodies targeting autoantigens from the nucleus. Given the complex pathophysiology of SLE and the role of TNF alpha in that disease, modulation of TNF alpha (in SLE or non-SLE patients) using TNF blockers could either be detrimental or beneficial in some patients. In this review we will focus on lupus autoantibodies and clinical manifestations after TNF blockade in SLE patients and conversely on drug-induced-SLE in non-SLE patients. Some hypotheses regarding the mechanism of induction of autoantibodies in RA patients treated with TNF blockers are proposed.     

Soluble tumour necrosis factor receptors,tumour necrosis factor and interleukin-6 in serum in granulocytopenic patients with fever

Serum levels of TNF, IL-6 and soluble TNF receptors p55 and p75 (sTNFR-p55 and sTNFR-p75) were examined in 14 patients with acute myeloid leukaemia during 43 courses of chemotherapy. The patients experienced 30 episodes of fever which occurred during granulocytopenia (defined as granulocyte counts <0.2×10⁹/1) and six fever episodes when granulocyte counts were >1.0×10⁹/1. Febrile episodes were classified as microbiologically defined infection, clinically defined infection, and unexplained fever. Levels of bioactive IL-6 and immunoreactive TNF increased in response to fever during granulocytopenia, whereas bioactive TNF was not detected in any sample in this study. During granulocytopenia, both sTNFR rose significantly in microbiologically defined infection (P<0.01 for sTNFR-p55 and P<0.05 for sTNFR-p75), but not in the other two categories. The ratio of sTNFR-p55 to sTNFR-p75 was higher during febrile periods in granulocytopenia than in a non-granulocytopenic situation with granulocyte counts >1.0×10⁹/1 (P<0.01). We conclude that granulocytopenia affects release of the two sTNFR differently during febrile periods, and that release of sTNFR-p75 in response to fever is reduced during granulocytopenia, suggesting a role for the granulocytes in systemic release of sTNFR-p75.     

Role of tumour necrosis factor (TNF) in host defence against tuberculosis: implications for immunotherapies targeting TNF

Studies in mouse infection models clearly demonstrate tumour necrosis factor (TNF) to be a critical component of both the antibacterially protective and the inflammatory immune response to Mycobacterium tuberculosis. It is therefore not surprising that treatment of patients-for example, those with rheumatoid arthritis-with biological agents interfering with TNF activity have shown an increased risk of reactivating tuberculosis. However, conceivably, TNF targeting biological agents can be developed that because of their particular mode of action and their specific pharmacodynamics may be less likely to have this side effect.     

Circulating tumour necrosis factor alpha and soluble tumour necrosis factor receptors in patients with different patterns of rheumatoid synovitis

OBJECTIVE: To examine the relation between the serum levels of tumour necrosis factor alpha (TNFalpha), soluble tumour necrosis factor receptors (sTNF-R), and the histological pattern of rheumatoid synovitis. METHODS: An enzyme linked immunosorbent assay (ELISA) was used to measure TNFalpha, p55 sTNF-R, and p75 sTNF-R concentrations in the serum of 43 patients with rheumatoid arthritis (RA) and 34 patients with osteoarthritis (OA). RESULTS: Upon histological analysis two variants of rheumatoid synovitis emerged. Twenty six RA specimens presented only diffuse infiltrates of mononuclear cells. In the remaining 17 samples the formation of lymphocytic follicles with germinal centre-like structures was found. Serum concentrations of TNFalpha, p55 and p75 sTNF-R were raised in patients with RA compared with the OA control group (p<0.001 for all comparisons). Levels of TNFalpha, p55 and p75 sTNF-R were higher in the serum of patients with RA with follicular synovitis than in patients with diffuse synovitis (p<0.001, p<0.01, and p<0.05, respectively). Serum concentrations of TNFalpha, p55 and p75 sTNF-R correlated with markers of disease activity. CONCLUSION: Different histological types of rheumatoid synovitis associated with distinct serum levels of TNFalpha and sTNF-R reflect varying clinical activity of the disease and support the concept of RA heterogeneity.     

Haplotypes in the tumour necrosis factor region and myeloma

This study described the haplotypic structure across a region of chromosome 6 including the tumour necrosis factor (TNF) gene, and investigated its influence on the aetiology of myeloma. A total of 181 myeloma cases from the Medical Research Council Myeloma VII trial and 233 controls from the Leukaemia Research Fund Case Control Study of Adult Acute Leukaemia were included in the analysis. Genotyping by induced heteroduplex generator analysis was carried out for single nucleotide polymorphisms (SNP) located at positions -1031, -863, -857, -308 and -238 of the 5' promoter region of TNF-alpha gene, and 252 in the LT-alpha gene; and five microsatellites, TNFa, b, c, d and e. Haplotypes were inferred statistically using the phase algorithm. A limited diversity of haplotypes was observed, with the majority of variation described by 12 frequent haplotypes. Detailed characterization of the haplotype did not provide greater determination of disease risk beyond that described by the TNF-alpha-308 SNP. Some evidence was provided for a decreased risk of myeloma associated with the TNF-alpha-308 variant allele A, odds ratio, 0.57; 95% confidence interval, 0.38-0.86. The results of this study did not support our starting hypothesis; that high producer haplotypes at the TNF locus are associated with an increased risk of developing myeloma.     

The utility of tumour necrosis factor blockade in orphan diseases

A variety of rheumatic disorders have been successfully treated with tumour necrosis factor (TNF) blockers. However, TNF blockade may be useful in a number of rare diseases. Preliminary data suggest that several forms of vasculitis appear responsive to TNF antagonists-Behcet's disease, Churg-Strauss vasculitis, polyarteritis nodosa, and giant cell arteritis, among others. Wegener's granulomatosis and sarcoidosis have been shown to improve with infliximab but not with etanercept. These results lend further support for the concept of differential mechanism(s) of action of the two antagonists with infliximab being more effective for the treatment of granulomatous diseases. Polymyositis/dermatomyositis may also be responsive to TNF blockade. TNF likely plays little role in Sjogren's syndrome as evidenced by the lack of efficacy of both TNF antagonists. Etanercept has been shown to be useful in the treatment of hepatitis C both in reducing the viral load and improving liver function. A number of other more rare disorders also may be responsive to TNF blockade. Further studies with larger numbers of well characterised patients and treatment regimens are necessary to provide more definitive evidence of the utility of the TNF antagonists in these serious and often life threatening diseases.     

Elevated B cell-activating factor of the tumour necrosis factor family in coeliac disease

OBJECTIVE: The B cell-activating factor of the tumour necrosis factor (TNF) family (BAFF) was recently described as a critical survival factor for B cells, and its expression is increased in several autoimmune diseases. Abnormal production of BAFF disturbs immune tolerance allowing the survival of autoreactive B cells and participates in the progression of B-cell lymphomas. Coeliac disease (CD) is a common autoimmune disorder induced by gluten intake in genetically predisposed individuals, associated with autoantibody production and with an increased risk of lymphoma at follow-up. The purpose of this study was to investigate the possible implications of BAFF in CD. MATERIAL AND METHODS: Seventy-three patients with small-bowel biopsies and laboratory-proven diagnosis of CD were included in the study. All serum samples were analysed before the start of a gluten-free diet (GFD). In 12 cases, one or more samples were analysed during follow-up of the GFD. Seventy-seven blood donors were taken as controls. Serum BAFF levels and anti-transglutaminase (a-tTG) antibodies were assessed by ELISA and endomysial antibodies by indirect immunofluorescence. RESULTS: Serum BAFF levels appeared to be significantly more elevated in CD patients than in controls (p<0.0001) and, compared with other autoimmune diseases where BAFF is increased, a much larger percentage (80.8%) of CD patients presented BAFF levels above the normal range. In addition, serum BAFF levels were found to correlate with a-tTG antibody levels (p =0.0007) and there was a significant reduction of BAFF after introduction of a GFD. CONCLUSIONS: BAFF may represent a possible pathogenic factor in CD. Its implications for the diagnosis, prognosis and treatment of CD should also be assessed.     

Elevated B cell-activating factor of the tumour necrosis factor family in coeliac disease

Objective. The B cell-activating factor of the tumour necrosis factor (TNF) family (BAFF) was recently described as a critical survival factor for B cells, and its expression is increased in several autoimmune diseases. Abnormal production of BAFF disturbs immune tolerance allowing the survival of autoreactive B cells and participates in the progression of B-cell lymphomas. Coeliac disease (CD) is a common autoimmune disorder induced by gluten intake in genetically predisposed individuals, associated with autoantibody production and with an increased risk of lymphoma at follow-up. The purpose of this study was to investigate the possible implications of BAFF in CD. Material and methods. Seventy-three patients with small-bowel biopsies and laboratory-proven diagnosis of CD were included in the study. All serum samples were analysed before the start of a gluten-free diet (GFD). In 12 cases, one or more samples were analysed during follow-up of the GFD. Seventy-seven blood donors were taken as controls. Serum BAFF levels and anti-transglutaminase (a-tTG) antibodies were assessed by ELISA and endomysial antibodies by indirect immunofluorescence. Results. Serum BAFF levels appeared to be significantly more elevated in CD patients than in controls (p<0.0001) and, compared with other autoimmune diseases where BAFF is increased, a much larger percentage (80.8%) of CD patients presented BAFF levels above the normal range. In addition, serum BAFF levels were found to correlate with a-tTG antibody levels (p=0.0007) and there was a significant reduction of BAFF after introduction of a GFD. Conclusions. BAFF may represent a possible pathogenic factor in CD. Its implications for the diagnosis, prognosis and treatment of CD should also be assessed.     

Production of tumour necrosis factor during murine cutaneous leishmaniasis

Summary We have assessed the role of tumour necrosis factor-α (TNF) during cutaneous leishmaniasis and demonstrated that significant levels of TNF were released by spleen cells from infected mice after in vitro restimulation with Leishmania major promastigotes. Spleen cells from both genetically resistant and genetically susceptible mice were equally capable of producing TNF. After challenge with bacterial endotoxin, TNF activity could also be demonstrated in the serum of L. major -infected mice and the titres correlated with the course of cutaneous disease in susceptible and resistant mice. TNF did not exert a direct leishmanicidal effect in vitro. Furthermore, our study indicated that macrophages are the source of L. major -induced TNF activity and that its elicitation is dependent on the presence of T cells. These findings suggest that TNF acts in concert with other cytokines produced during L. major infection and that its role depends on the composition of T cell subsets and cytokines present.     

Crohn's disease: beyond antagonists of tumour necrosis factor

In the past few years, antagonists of tumour necrosis factor have resulted in unforetold therapeutic benefits in Crohn's disease, but the magnitude and duration of responses are variable. New agents are therefore needed. Their development has benefited from advances in the understanding of the pathophysiology of this disease. Uncontrolled activation of the acquired immune system has an important role, and lymphocytes, cytokines, and adhesion molecules are broadly targeted for therapeutic intervention. With increasing evidence of an implication of the innate immune system and the intestinal epithelium, the therapeutic paradigm is also shifting from mere immunosuppression to the reinforcement of the intestinal barrier. We review mechanisms of actions of new drugs and the efficacy and adverse events from data from clinical trials. We discuss future directions, including new strategies with optimum endpoints.     

Production of tumour necrosis factor during murine cutaneous leishmaniasis

We have assessed the role of tumour necrosis factor-alpha (TNF) during cutaneous leishmaniasis and demonstrated that significant levels of TNF were released by spleen cells from infected mice after in vitro restimulation with Leishmania major promastigotes. Spleen cells from both genetically resistant and genetically susceptible mice were equally capable of producing TNF. After challenge with bacterial endotoxin, TNF activity could also be demonstrated in the serum of L. major-infected mice and the titres correlated with the course of cutaneous disease in susceptible and resistant mice. TNF did not exert a direct leishmanicidal effect in vitro. Furthermore, our study indicated that macrophages are the source of L. major-induced TNF activity and that its elicitation is dependent on the presence of T cells. These findings suggest that TNF acts in concert with other cytokines produced during L. major infection and that its role depends on the composition of T cell subsets and cytokines present.     

Therapeutic considerations in spondyloarthritis patients who fail tumour necrosis factor antagonists

The tumour necrosis factor (TNF) antagonists have significantly improved quality of life and functional status in patients with spondyloarthritis (SpA). The excitement regarding the remarkable success of these agents is justified but challenges remain. In particular, alternative systemic therapies with proven efficacy for patients who fail TNF antagonists have been developed in rheumatoid arthritis but are not yet available in SpA. In this article, the approach to patients with psoriatic arthritis (PsA) or ankylosing spondylitis (AS) who fail TNF antagonists will be discussed with the goal of providing a path to the clinician, who must manage these patients amidst uncertainty. Three central questions will be addressed. Why does a particular SpA patient not respond to a TNF antagonist? How can the clinician improve the probability of treatment response in patients who fail a TNF antagonist? What specific approaches can be taken to control disease activity in PsA or AS following treatment failure with a TNF antagonist? Data from controlled trials, registries and pilot studies will be combined with expert opinion to address these important questions.