Native inhibitors (autoantibodies) of IL-1 alpha and TNF

Tolerogenic microenvironment in neonatal period induced by maternal immunization with ovalbumin

Maternal immunization with allergens, such as ovalbumin (OVA), can inhibit the development of an allergic response in offspring. The regulatory mechanisms seem to be mediated by maternal antibodies (MatAbs) and factors generated by the maternal-fetal interface. The aim of this study was to verify the pathways of inhibitory Ab transference after maternal immunization with OVA and the effect of the offspring's dendritic cells (DCs) on the generation of regulatory T (Treg) cells. We verified that preconceptional OVA immunization induces high levels of proinflammatory and regulatory cytokines in the amniotic fluid, allowing the transference of high levels of anti-OVA IgG1 Abs to the offspring. Using an adoptive nursing protocol, we verified that maternal immunization leads to MatAb transference by the placental route and by breastfeeding contribute to the inhibition of anaphylactic IgE and IgG1 Ab responses in immunized offspring. We observed that maternal immunization decreased eosinophil numbers in recovered bronchoalveolar lavage fluid and in the lung tissue, whereas with a lack of control of airway responsiveness to methacholine. Maternal immunization induced in young offspring a decreased percentage of CD11c+ DCs expressing MHC class II and CD40 molecules. Moreover, DCs from both groups of offspring when pulsed with OVA, were able to induce Treg cells in vitro. Similarly, OVA immunization at the neonatal stage increased the frequency of Treg cells, regardless of the mother's immunization status. These findings emphasize that maternal immunization leads to a complex interaction of regulatory factors, with MatAbs, DCs and Treg cells affecting the tolerance of offspring during an allergic response.

Natural antibodies against bone morphogenic proteins and interferons in healthy donors and in patients with infections linked to type-1 cytokine responses

In patients receiving recombinant therapeutic proteins, the production of antibodies against the therapeutics is a rising problem. The antibodies can neutralize and interfere with the efficacy and safety of drugs and even cause severe side effects if they cross-react against the natural, endogenous protein. Various factors have been identified to influence the immunogenic potential of recombinant human therapeutics, including several patients' characteristics. In recent years, so-called naturally occurring antibodies against cytokines and growth factors have been detected in naive patients before start of treatment with recombinant human therapeutics. The role of naturally occurring antibodies is not well understood and their influence on production of anti-drug antibodies is not known. One might speculate that the presence of naturally occurring antibodies increases the likelihood of eliciting anti-drug antibodies once treatment with the corresponding recombinant therapeutic protein is started. We screened serum samples from 410 healthy controls and patients for auto-antibodies against bone morphogenetic proteins (BMPs) 2 and 7 and interferon (IFN)-α, -β, and -γ in a new 3-step approach: rough initial screening, followed by competition and protein A/G depletion. Naturally occurring antibodies against these proteins were detected in 2% to 4% of the tested sera. Individuals who are 65 years or older had a slightly higher occurrence of naturally occurring antibodies. Auto-antibodies against BMP-7 and IFN-α were mainly comprised of IgM isotypes, and natural antibodies against BMP-2, IFN-β, and -γ were mainly IgG. To ensure assay specificity, assays were also used to detect antibodies against BMP-7 in patients being treated with rhBMP-7 before and after surgical procedure. Fifty percent of the treated patients had persistent anti-BMP-7 antibodies over time. The 3-step approach provides an attractive tool to identify naturally occurring antibodies in naive patients.

Interleukins in atherosclerosis: molecular pathways and therapeutic potential

Interleukins are considered to be key players in the chronic vascular inflammatory response that is typical of atherosclerosis. Thus, the expression of proinflammatory interleukins and their receptors has been demonstrated in atheromatous tissue, and the serum levels of several of these cytokines have been found to be positively correlated with (coronary) arterial disease and its sequelae. In vitro studies have confirmed the involvement of various interleukins in pro-atherogenic processes, such as the up-regulation of adhesion molecules on endothelial cells, the activation of macrophages, and smooth muscle cell proliferation. Furthermore, studies in mice deficient or transgenic for specific interleukins have demonstrated that, whereas some interleukins are indeed intrinsically pro-atherogenic, others may have anti-atherogenic qualities. As the roles of individual interleukins in atherosclerosis are being uncovered, novel anti-atherogenic therapies, aimed at the modulation of interleukin function, are being explored. Several approaches have produced promising results in this respect, including the transfer of anti-inflammatory interleukins and the administration of decoys and antibodies directed against proinflammatory interleukins. The chronic nature of the disease and the generally pleiotropic effects of interleukins, however, will demand high specificity of action and/or effective targeting to prevent the emergence of adverse side effects with such treatments. This may prove to be the real challenge for the development of interleukin-based anti-atherosclerotic therapies, once the mediators and their targets have been delineated.

Fibroproliferative scars

Fibroproliferative scars remain an ongoing clinical challenge. Both hypertrophic scars and keloids require multimodal therapy toachieve partally successful treatment. At the present time incomplete understanding about the pathogenesis of fibroproliferative scars makes targeted, mechanistic treatment impossible. As understanding of these abnormal wound problems increases, more effective treatments will likely be available. Until that time, clinicians must utilize existing knowledge to treat patients while continuing to experiment with new approaches.

Natural and therapeutically-induced antibodies to cytokines

Serum samples obtained from non-immunocompromised patients treated therapeutically with recombinant cytokines (e.g. Il-1alpha; Il-1beta; Il-2 to Il-18; IFNalpha; GM-CSF; G-CSF; etc.) often reveal the presence of high affinity anti-cytokine antibodies. Antibody Fab binding in a saturable manner by ELISA and RIA or western immunoblotting prove their specificity. Antibody level often increases in these patients with repeated cytokine administration, suggesting boosts of antigen stimulation. However, the appearance in circulation of auto-antibodies to exogenous cytokine is not always associated with a decreased clinical response to therapy. The demonstration that non-neutralizing auto-antibodies to several natural cytokines can be found even in sera of normal healthy individuals never treated before with cytokines and particularly during the last trimester of pregnancy and in cord-blood, suggests that these naturally- occurring and therapeutically-induced auto-antibodies may exert different functions, not only as inhibitors or antagonists but also as beneficial physiological cytokine carriers or regulators of their activity.

Circulating plasma receptors for tumour necrosis factor in Malawian children with severe falciparum malaria

Tumour necrosis factor (TNF) concentrations are increased in the plasma during a malarial illness, and are highest in patients with severe or fatal disease. We have studied the plasma concentrations of two soluble receptors (sTNF-R1 and sTNF-R2), which act as binding proteins for TNF, in children with falciparum malaria. In 52 Malawian children with malaria, plasma concentrations of both sTNF-R1 (mean (S.D.) 4759(2552) pg/ml) and sTNF-R2 (59077(37102) pg/ml) were greatly increased when compared with levels of convalescence (sTNF-R1 718(68), and sTNF-R2 8015(7021) pg/ml), and in controls without malaria (486(1353) and 4380(2168)). Concentrations of both receptors correlated with plasma levels of TNF measured by immunoradiometric assay, but not with those of another cytokine, IL-6. The mean plasma concentrations of both immunoreactive TNF and soluble TNF receptors were greater in patients with cerebral malaria than those with uncomplicated malaria. Despite high levels of immunoreactive TNF in the plasma of patients acutely ill with malaria, no bioactive TNF could be detected in these patients by the WEHI cell bioassay. Soluble TNF receptors are present in greatly increased concentrations in the plasma of patients with malaria and may play a role in mediating or modulating the pathogenetic effects of the cytokine.

Scar wars strategies. Target collagen

Hypertrophic scarring and keloid formation are clinical problems with effectively limited solutions. Although numerous methods have been devised to combat them, this article focuses on promising pharmacologic strategies that target collagen metabolism. Laboratory investigations of amino-acid analogs, procollagen peptides, D-penicillamine, and pentoxifylline have demonstrated them to be effective inhibitors of collagen synthesis in cultured cells and/or in animal models. Clinical trials of intralesional administration of interferons have shown impressive reductions in the size and collagen production of keloids. Furthermore, interference of extracellular matrix-enhancing cytokines, such as TGF-beta, may be an effective solution to keloids and hypertrophic scars. Additional research of soluble cytokine receptors, autoantibodies to cytokines, cytokine receptor antagonists, and cytokine-binding molecules may lead to the development of better therapeutic agents.

Anti-interleukin-1 alpha autoantibodies in hemodialysis patients

IL-1 activity is increased in hemodialysis patients and interest has recently been focused on IL-1 antagonism in various clinical settings. We studied the presence of anti-IL-1 alpha autoantibodies in sera from 49 hemodialysis patients, 159 kidney graft recipients and 89 chronic renal failure patients without renal replacement therapy. Within the three month study period 32.6% of the hemodialysis patients were found to present with anti-IL-1 alpha autoantibodies, in contrast to 5.6% of kidney graft recipients, 8.9% of chronic renal failure patients, and only 1.4% of healthy subjects. The presence of these autoantibodies was neither associated with primary kidney disease nor with the type of dialysis membrane we used. In addition, in antibody positive patients a pronounced increase of IL-1 alpha serum levels within a dialysis session from 14.8 +/- 4.7 pg/ml to 26.4 +/- 11.2 pg/ml (P less than 0.0005) was observed, contrasting to the more even increase from 14.1 +/- 3.1 pg/ml to 19.3 +/- 12.7 pg/ml (P less than 0.05) in the antibody negative group. Neither clinical symptoms due to adverse effects of IL-1 alpha nor some influence on erythropoiesis mediated by IL-1 alpha could be envisaged. Thus, we believe, that anti-IL-1 alpha autoantibodies, present in high frequency in hemodialysis patients, have a neutralizing effect on IL-1 alpha in these patients.

Distribution and characterization of autoantibodies to interleukin 1 alpha in normal human sera

Antibodies against IL-1 alpha were detected in sera of apparently healthy individuals. The immunoglobulins belonged to the IgG class, particularly IgG1, IgG2, and IgG4. [125I]rIL-1 alpha bound to Fab fragments of IgG, and IgG immune complexes of molecular weights from 160 to 700 kDa were formed in the sera by [125I]rIL-1 alpha. The occurrence of detectable anti-IL-1 alpha IgG in sera of 32 male and 32 female donors was 25 and 22% respectively. As judged by Scatchard analysis of the binding data, the capacity and avidity of binding were greater in the male than in the female sera (mean capacity to bind [125I]rIL-1 alpha: 10 [0.7-27] versus 3.3 [0.5-7.3] ng/ml; and mean Kd: 5.5 [5-7] versus 11 [4-16] pM). The antibodies did not cross-bind human recombinant IL-1 beta, IL-2, IL-6, or tumour necrosis factor alpha (TNF-alpha). It is concluded that native IL-1 alpha seems to trigger production of specific, high-avidity IgG antibodies in a relatively large number of normal individuals. These autoantibodies may regulate immunoinflammatory processes involving IL-1 alpha.

Autoantibodies to cytokines--friends or foes?

Cytokines form a network of communication signals between cells of the immune system, and between the immune system and other organs. They interact with structurally complex and often dynamically expressed target cell receptors. The recent demonstration of autoantibodies to cytokines, even in sera of normal individuals, suggests further complexities in the way that nature regulates cytokine functions. Based mainly on evidence obtained by investigating autoantibodies to interleukin 1 alpha (IL-1 alpha), Klaus Bendtzen and colleagues discuss the possibility that naturally occurring antibodies may function as specific physiological carriers and regulators of cytokines.

Human urine deoxyribonuclease increases endogenous thymidine in the mouse thymocyte interleukin 1 assay: an artificial interleukin-1 inhibitor

Molecular size chromatography of urine from normal individuals showed two peaks of apparent IL-1 suppressive activities when tested by the murine thymocyte comitogenic assay (mol wt greater than 600 kD and 20 to 60 kD). However, the high molecular weight inhibitory activity disappeared if the concentration of PHA was increased during assay, and the low molecular weight inhibitory activity subsided in the presence of a high concentration of [3H]thymidine. The 20 to 60 kD fractions contained DNase activity which acted on DNA liberated from the considerable number of dying thymocytes during the course of the assay. Thus, incubating the urine fractions with freeze-killed murine T cells, whose DNA was prelabeled with [3H]thymidine, showed the appearance of supernatant [3H]thymidine correlating quantitatively with the DNase activity in the fractions. This indicates that urine DNase together with phosphatase(s) in the thymocyte cultures increase the level of extracellular, unlabeled thymidine, thereby diluting the specific activity of the tracer. These artificial IL-1-inhibitors may explain why urine from both normal and febrile individuals 'inhibits' IL-1 only when tested for thymocyte-activating activity but not when tested for other biological activities.