Detection of autoantibodies to cytokines

Use of Intravenous Immunoglobulins in Sepsis Therapy-A Clinical View

Sepsis is a life-threatening organ dysfunction, defined by a dysregulated host immune response to infection. During sepsis, the finely tuned system of immunity, inflammation and anti-inflammation is disturbed in a variety of ways. Both pro-inflammatory and anti-inflammatory pathways are upregulated, activation of the coagulation cascade and complement and sepsis-induced lymphopenia occur. Due to the manifold interactions in this network, the use of IgM-enriched intravenous immunoglobulins seems to be a promising therapeutic approach. Unfortunately, there is still a lack of evidence-based data to answer the important questions of appropriate patient populations, optimal timing and dosage of intravenous immunoglobulins. With this review, we aim to provide an overview of the role of immunoglobulins, with emphasis on IgM-enriched formulations, in the therapy of adult patients with sepsis and septic shock.

Gasotransmitters and the immune system: Mode of action and novel therapeutic targets

Gasotransmitters are a group of gaseous molecules, with pleiotropic biological functions. These molecules include nitric oxide (NO), hydrogen sulfide (H₂S), and carbon monoxide (CO). Abnormal production and metabolism of these molecules have been observed in several pathological conditions. The understanding of the role of gasotransmitters in the immune system has grown significantly in the past years, and independent studies have shed light on the effect of exogenous and endogenous gasotransmitters on immune responses. Moreover, encouraging results come from the efficacy of NO-, CO- and H₂S -donors in preclinical animal models of autoimmune, acute and chronic inflammatory diseases. To date, data on the influence of gasotransmitters in immunity and immunopathology are often scattered and partial, and the scarcity of clinical trials using NO-, CO- and H₂S -donors, reveals that more effort is warranted. This review focuses on the role of gasotransmitters in the immune system and covers the evidences on the possible use of gasotransmitters for the treatment of inflammatory conditions.

Development and effect of antibodies to anakinra during treatment of severe CAPS: sub-analysis of a long-term safety and efficacy study

Anakinra is an effective, well-tolerated, long-term anti-inflammatory treatment for cryopyrin-associated periodic syndromes (CAPS), yet evidence shows that it can induce the development of anti-drug antibodies (ADA). This analysis aims to determine ADA occurrence in CAPS patients and elucidate their effects on anakinra dosing and drug efficacy. A post hoc analysis was performed on data from a long-term safety and efficacy study in patients with severe CAPS. Patients were initiated on an anakinra dose of 1.0-2.4 mg/kg once daily subcutaneously, which was increased (in 0.5-1.0 mg/kg increments) to 2.0-5.0 mg/kg/day according to clinical need (median 3.1 mg/kg/day). ADA, serum amyloid A (SAA), and C-reactive protein (CRP) levels were measured at various time points, and pharmacokinetic (PK) parameters at 1 and 3 months. Efficacy was evaluated using a diary symptom sum score (DSSS), and SAA and CRP levels were evaluated as proxies of efficacy. Safety was evaluated by an analysis of adverse events (AEs). Anakinra dose levels were unrelated to ADA status. A high proportion of patients with at least one post-baseline assessment developed ADA (83%), the majority (79%) within 3 months. However, anakinra treatment markedly improved symptoms and was effective regardless of the presence of ADA; the annual rates of AEs were comparable between ADA-negative and ADA-positive patients. While ADA are likely to occur in CAPS patients treated with anakinra, our evidence shows that chronic daily subcutaneous treatment with anakinra is safe and effective regardless of the development and presence of ADA.

Measuring and evaluating interferon b-induced antibodies in patients with multiple sclerosis

Author for correspondence: Klaus Bendtzen, Institute for Inflammation Research IIR 7521, Rigshospitalet University Hospital, 9 Blegdamsvej, DK-2100 Copenhagen, Denmark. E-mail: address: kben@mail.dk Administration of interferons (IFNs) may induce antibodies that interfere with therapeutic efficacy. We have optimized and validated methods for large-scale economic screening. Sera from patients with relapsing-remitting multiple sclerosis (MS) were investigated for binding antibody (BAb) by protein-G affinity-chromatography radioimmunoassay and a commercially available enzyme immunoassay (EIA). Neutralizing antibody (NAb) was investigated by cytopathic effect assays (CEA) using both fixed amount and serially diluted sera. BAb correlated with log10-transformed titres obtained by EIA (r=0.70, p<0.0001); the latter, however, failed to demonstrate low-level BAb. Comparison of clinical significance of NAb-positivity measured by biological assays with different sensitivities demonstrated an optimal odds ratio for relapse rate using 10 laboratory units (LU)/mL. Purification of IgG prior to CEA removed toxicity from toxic sera. The neutralizing capacity data correlated linearly with log10-transformed titres obtained by a Kawade 10-to-1 LU/mL CEA (r=0.77, p<0.0001). In conclusion, neutralizing capacity CEA utilizing a fixed amount of serum predicts differences in relapse rates in IFNβ-treated MS patients and correlates with NAb titres of the 10-to- 1 LU/mL CEA. Neutralizing capacity CEA is less laborious and more economical than titre-based NAb assays and suitable for large-scale screenings of MS patients.

Levels of TNF, TNF autoantibodies and soluble TNF receptors in patients with bronchial asthma

OBJECTIVES

The aim of the study was to evaluate the potential contribution made by tumor necrosis factor (TNF) autoantibodies to the pathogenesis of bronchial asthma (BA).

METHODS

We used affinity chromatography methods and a magnetic separation procedure to purify human autoantibodies specific to TNF. The autoantibodies were used as a calibration material to determine the absolute content of autoantibodies to TNF using enzyme-linked immunosorbent assay (ELISA). TNF content and levels of soluble receptors to TNF were determined using the ELISA commercial test kits.

RESULTS

We demonstrated significant increases in the levels of TNF and soluble TNF receptors in the sera of patients with uncontrolled and controlled BA, as compared with healthy donors. Levels of autoantibodies of the IgG2 and IgG4 subclasses were significantly higher in sera from patients with uncontrolled BA than in healthy donors. Levels of IgG2 autoantibodies were significantly higher in sera from patients with uncontrolled BA than in patients with controlled BA.

CONCLUSIONS

BA is associated with changes in the levels of not only TNF and soluble receptors for TNF, but also autoantibodies to TNF. Given the magnitude of the changes in the levels of different subclasses of autoantibodies to TNF, we propose that these autoantibodies might contribute to the pathogenesis of BA.

Bench-to-bedside review: Immunoglobulin therapy for sepsis - biological plausibility from a critical care perspective

Sepsis represents a dysregulated host response to infection, the extent of which determines the severity of organ dysfunction and subsequent outcome. All trialled immunomodulatory strategies to date have resulted in either outright failure or inconsistent degrees of success. Intravenous immunoglobulin (IVIg) therapy falls into the latter category with opinion still divided as to its utility. This article provides a narrative review of the biological rationale for using IVIg in sepsis. A literature search was conducted using the PubMed database (1966 to February 2011). The strategy included the following text terms and combinations of these: IVIg, intravenous immune globulin, intravenous immunoglobulin, immunoglobulin, immunoglobulin therapy, pentaglobin, sepsis, inflammation, immune modulation, apoptosis. Preclinical and extrapolated clinical data of IVIg therapy in sepsis suggests improved bacterial clearance, inhibitory effects upon upstream mediators of the host response (for example, the nuclear factor kappa B (NF-κB) transcription factor), scavenging of downstream inflammatory mediators (for example, cytokines), direct anti-inflammatory effects mediated via Fcγ receptors, and a potential ability to attenuate lymphocyte apoptosis and thus sepsis-related immunosuppression. Characterizing the trajectory of change in immunoglobulin levels during sepsis, understanding mechanisms contributing to these changes, and undertaking IVIg dose-finding studies should be performed prior to further large-scale interventional trials to enhance the likelihood of a successful outcome.

Immunoregulation by naturally occurring and disease-associated autoantibodies : binding to cytokines and their role in regulation of T-cell responses

The role of naturally occurring autoantibodies (NAbs) in homeostasis and in disease manifestations is poorly understood. In the present chapter, we review how NAbs may interfere with the cytokine network and how NAbs, through formation of complement-activating immune complexes with soluble self-antigens, may promote the uptake and presentation of self-molecules by antigen-presenting cells. Both naturally occurring and disease-associated autoantibodies against a variety of cytokines have been reported, including NAbs against interleukin (IL)-1α, IL-6, IL-8, IL-10, granulocyte-macrophage colony-stimulating factor, interferon (IFN)-α, IFN-β, IFN-γ, macrophage chemotactic protein-1 and IL-21. NAbs against a variety of other self-antigens have also been reported, and using thyroglobulin as an example we discuss how NAbs are capable of promoting uptake of immune complexes via complement receptors and Fc-receptors on antigen-presenting cells and thereby regulate T-cell activity. Knowledge of the influence of NAbs against cytokines on immune homeostasis is likely to have wide-ranging implications both in understanding pathogenesis and in treatment of many immunoinflammatory disorders, including a number of autoimmune and autoinflammatory diseases.

Characterization of specific antibodies against cytomegalovirus (CMV)-encoded interleukin 10 produced by 28% of CMV-seropositive blood donors

Cytomegalovirus (CMV) has evolved multiple immunological evasion strategies, including the encoding of viral interleukin (IL)-10 homologues (cmvIL-10). In this study, cmvIL-10 bound avidly to the same receptors on blood mononuclear cells and was as bio-potent as native human IL-10. Seventeen percent of plasma samples from 3200 Danish blood donors (corresponding to 28 % of the anti-CMV IgG-positive donors) contained substantial levels of anti-cmvIL-10 IgG antibodies, as measured by a radioimmunoassay for human anti-cmvIL-10 antibodies. The antibodies neither cross-reacted with native human IL-10 nor with Epstein-Barr virus-encoded IL-10. Anti-cmvIL-10 antibodies potently inhibited the binding of cmvIL-10 to cellular receptors, and they specifically inhibited cmvIL-10-induced JAK-STAT signalling. Ultimately, anti-cmvIL-10 antibodies blocked the inhibitory effect of cmvIL-10 on lipopolysaccharide-induced tumour necrosis factor alpha and IL-1β from blood mononuclear cells. Taken together, our data signify that cmvIL-10 has been produced during CMV infection, and that anti-cmvIL-10 IgG antibodies represent an effective immunological counter reaction against cmvIL-10.

Critical review: assessment of interferon-β immunogenicity in multiple sclerosis

This review discusses type I interferon (IFN) immunogenicity with focus on methods of detection of anti-IFN antibodies in patients treated with human recombinant IFN-&#x03B2;. Pitfalls involved in the clinical use of various types of assays for binding antibodies and neutralizing antibodies against IFN-&#x03B2; are presented, and the widely held distinction between binding antibodies and neutralizing antibodies is questioned both in terms of detection and clinical importance. The article also addresses important bioavailability and pharmacokinetic issues occurring with prolonged use of protein drugs. The rationale for individualized or personalized medicine, ie, optimizing therapies according to individual needs rather than using standardized trial-and-error regimens to all patients, is highlighted.

Beware of Antibodies to Dietary Proteins in “Antigen-specific” Immunoassays! Falsely Positive Anticytokine Antibody Tests Due to Reactivity with Bovine Serum Albumin in Rheumatoid Arthritis (The Swedish TIRA Project)

Objective.

To evaluate (1) to what extent sera from healthy subjects and patients with rheumatoid arthritis (RA) contain antibodies to bovine serum albumin (BSA); and (2) if anti-BSA antibodies interfere with results of enzyme-linked immunoassays (ELISA) containing BSA.

Methods.

The ELISA used was a previously developed in-house assay of autoantibodies to tumor necrosis factor (TNF). Anti-TNF and anti-BSA antibodies were analyzed by ELISA in 189 patients with early RA and 186 healthy blood donors. TNF preparations containing either BSA or human serum albumin (HSA) as carrier proteins were used as antigens in the anti-TNF assay. The presence and levels of antibodies were analyzed in relation to disease course and to the presence/absence of rheumatoid factor (RF).

Results.

In patients with RA, anti-TNF/BSA levels strongly correlated with anti-BSA levels (r = 0.81, p < 0.001), whereas anti-TNF/HSA did not (r = −0.09). Neither the presence nor the levels of anti-BSA in RA patients were associated with disease progression, and antibody levels were not significantly altered compared to controls (p = 0.11). IgG reactivity with TNF/HSA was neglible. In paired sera, preincubation with BSA abolished the anti-TNF/BSA reactivity. There were no indications of RF interference with anti-BSA or anti-TNF reactivity.

Conclusion.

Antibodies to BSA are common in patients with RA as well as in healthy individuals. Their presence does not seem to be associated with RA disease activity or disease course, but may severely interfere with ELISA containing BSA. The use of BSA as a “blocking agent” or carrier protein in immunoassays should therefore be avoided.

Alpha-1-antitrypsin is an endogenous inhibitor of proinflammatory cytokine production in whole blood

Several observations suggest endogenous suppressors of inflammatory mediators are present in human blood. alpha-1-Antitrypsin (AAT) is the most abundant serine protease inhibitor in blood, and AAT possesses anti-inflammatory activity in vitro and in vivo. Here, we show that in vitro stimulation of whole blood from persons with a genetic AAT deficiency resulted in enhanced cytokine production compared with blood from healthy subjects. Using whole blood from healthy subjects, dilution of blood with RPMI tissue-culture medium, followed by incubation for 18 h, increased spontaneous production of IL-8, TNF-alpha, IL-1 beta, and IL-1R antagonist (IL-1Ra) significantly, compared with undiluted blood. Dilution-induced cytokine production suggested the presence of one or more circulating inhibitors of cytokine synthesis present in blood. Serially diluting blood with tissue-culture medium in the presence of cytokine stimulation with heat-killed Staphylococcus epidermidis (S. epi) resulted in 1.2- to 55-fold increases in cytokine production compared with S. epi stimulation alone. Diluting blood with autologous plasma did not increase the production of IL-8, TNF-alpha, IL-1 beta, or IL-1Ra, suggesting that the endogenous, inhibitory activity of blood resided in plasma. In whole blood, diluted and stimulated with S. epi, exogenous AAT inhibited IL-8, IL-6, TNF-alpha, and IL-1 beta significantly but did not suppress induction of the anti-inflammatory cytokines IL-1Ra and IL-10. These ex vivo and in vitro observations suggest that endogenous AAT in blood contributes to the suppression of proinflammatory cytokine synthesis.

Development of a Maturing T-Cell-Mediated Immune Response in Patients with Idiopathic Parkinson’s Disease Receiving r-metHuGDNF Via Continuous Intraputaminal Infusion

The development of a maturing T-cell-mediated immune response was characterized in Parkinson's disease subjects receiving recombinant human glial-derived neurotrophic factor (r-metHuGDNF) via continuous bilateral intraputaminal infusion. Eighteen of 34 subjects tested positive for anti-r-metHuGDNF-binding antibodies. Four subjects developed neutralizing activity, three of which demonstrated classic immunoglobulin class switching from IgM to IgG. An increase of anti-r-metHuGDNF IgG-binding antibodies correlated with the development of neutralizing activity. All serum samples from two subjects with neutralizing activity were characterized for IgG subclasses. These data revealed an initial anti-r-metHuGDNF IgG population where IgG1 >> IgG2 >> IgG4, and IgG3 concentrations were negligible. However, continued antigenic stimulation resulted in concentration changes where IgG4 > IgG1> IgG2, indicating a mature immune response. In addition, using in silico techniques, two immunodominant MHC class II T-cell epitopes were predicted for the native GDNF sequence. These data demonstrate development of a mature T-cell-mediated immune response in these subjects.

Cytokine profiles in peripheral blood and whole blood cell cultures associated with aggressive periodontitis, juvenile idiopathic arthritis, and rheumatoid arthritis

BACKGROUND

Cytokines play a key role in the pathogenesis of inflammatory diseases. An obvious question is whether patients with aggressive periodontitis, juvenile idiopathic arthritis, or rheumatoid arthritis share blood cytokine profiles distinguishing them from individuals free of disease.

METHODS

The study population consisted of Danish white adults, <35 years of age, diagnosed with localized aggressive periodontitis (LAgP; N = 18), generalized aggressive periodontitis (GAgP; N = 27), juvenile idiopathic arthritis (JIA; N = 10), or rheumatoid arthritis (RA; N = 23) and healthy individuals with no systemic or oral diseases (control [CTRL]; N = 25). Enzyme-linked immunosorbent assays were used to determine the levels of interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-10, tumor necrosis factor (TNF)-alpha, and lymphotoxin (LT)-alpha in peripheral blood (plasma) and unstimulated and stimulated whole blood cell cultures from the same blood collection. Autoantibodies (aAb) to IL-1alpha and IL-6 were quantitated by radioimmunoassay.

RESULTS

Similar patterns of slightly higher IL-10 levels in plasma were found for GAgP and RA patients and in unstimulated cultures for GAgP, RA, and JIA patients. Interestingly, unstimulated cultures also demonstrated similar patterns of higher TNF-alpha levels for these three groups of patients. Similar group patterns of periodontitis patients (LAgP and GAgP) included increased IL-1Ra levels in stimulated cultures, which also showed similar group patterns of arthritis patients (JIA and RA) with respect to higher IL-1alpha and lower LT-alpha levels. Low titers of aAb to IL-1alpha and IL-6 were found in almost all individuals.

CONCLUSION

Patients with aggressive periodontitis and types of arthritis presented with similar components of blood cytokine profiles distinguishing them from individuals free of disease.

Biochip as a potential platform of serological interferon α2b antibody assay

The formation of antibodies against cytokines may play a major role in the generation of the immune response and may affect treatment protocols with recombinant cytokines. Interferon (IFN) is one of the effective therapeutic agents with anti-viral and anti-tumor specific effects. The appearance of IFN antibodies in patients may limit the natural and the therapeutic effect by IFNs. In contrast to conventional ELISA techniques, we here report a simple biochip methodology that enables identification of antibodies against cytokines and peptides. The method takes advantage of a functionalized self-assembled monolayer modified by N-hydroxysuccinimide (NHS). To validate this surface, four human proteins: IFNalpha2b, leptin, growth hormone and human IgG, with molecular sizes ranging between 14 and 150 kDa, were used. A number of other parameters for protein assay conditions by array technology were evaluated concomitantly. Finally, 56 serum samples from patients treated with recombinant human IFNalpha2b were simultaneously tested on single chip. In these patients, 16.1% (9 of 56 cases) were positive for IFNalpha2b antibodies. All results were confirmed in an ELISA, specific for the identification of IFNalpha specific antibodies in human samples. The potential application of this protein biochip can be amplified rapidly and reliably to test not only IFNalpha2b, but also other cytokine specific antibodies. The clinical relevance of such assays for investigations in autoimmune disorders is expected.

Identification of natural antibodies to interleukin-18 in the sera of normal humans and three nonhuman primate species

Natural antibodies to cytokines can be found in the sera of normal healthy individuals in the absence of specific immunostimulation. However, the function, impact, and purpose of natural antibody development have yet to be fully elucidated. Interleukin (IL)-18 is a cytokine that exerts proinflammatory activities and induces natural killer (NK) cell activity. Recombinant human IL-18 (rHuIL-18) is currently in development as a cancer immunotherapy. In this study, the presence of natural antibodies to IL-18 in the sera of normal humans and three nonhuman primate species was evaluated by electrochemiluminescence immunoassay (ECLIA). Of the human sera tested, 6 of 47 samples were positive for natural antibodies to IL-18. Of the nonhuman primate sera tested, 22 of 80 cynomolgus monkey samples, 4 of 31 rhesus monkey samples, and 2 of 20 chimpanzee samples were positive for natural antibodies to IL-18. Natural anti-IL-18 antibodies were neutralizing in 5 of 22 cynomolgus and 2 of 4 rhesus sera. None of the chimpanzee or human sera were able to neutralize IL-18 induction of interferon (IFN)-gamma in vitro. In vivo activity of rHuIL-18 was compared in IL-18 natural antibody-positive and -negative cynomolgus monkeys. The presence of natural antibodies to IL-18 did not alter rHuIL-18 systemic exposure levels, induction of neopterin, or induction of treatment-induced antibodies following intravenous administration of rHuIL-18. In conclusion, our data indicate that, as has been found with other cytokines, natural anti-IL-18 antibodies are relatively common. Moreover, natural anti-IL-18 antibodies do not appear to influence rHuIL-18 activity in vivo and are not predictive of a heightened immune response, suggesting that natural anti-IL-18 antibodies do not impact IL-18 therapy. Finally, our data suggest that the ability to detect natural anti-cytokine antibodies may be a useful measure of the adequacy of an assay for deployment in clinical trials.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.