Interleukin-10 and interleukin-4 have similar effects on hapten-specific primary antibody responses to penicillin in vivo

Blocking interleukin-4 enhances efficacy of vaccines for treatment of opioid abuse and prevention of opioid overdose

Vaccines offer an option to treat heroin and prescription opioid abuse and prevent fatal overdoses. Opioid vaccines elicit antibodies that block opioid distribution to the brain and reduce opioid-induced behavioral effects and toxicity. The major limitation to the translation of addiction vaccines is that efficacy is observed only in subjects achieving optimal drug-specific serum antibody levels. This study tested whether efficacy of a vaccine against oxycodone is increased by immunomodulators targeting key cytokine signaling pathways involved in B and T cell lymphocyte activation. Blockage of IL-4 signaling increased vaccine efficacy in blocking oxycodone distribution to the brain and protection against opioid-induced behavior and toxicity in mice. This strategy generalized to a peptide-protein conjugate immunogen, and a tetanus-diphtheria-pertussis vaccine. These data demonstrate that cytokine-based immunomodulators increase efficacy of vaccines against small molecules, peptides and proteins, and identify IL-4 as a pharmacological target for improving efficacy of next-generation vaccines.

T cell proliferative responses to malondialdehyde-acetaldehyde haptenated protein are scavenger receptor mediated

Malondialdehyde-acetaldehyde (MAA) haptenated proteins have been described in disease processes related to prolonged oxidative stress (via malondialdehyde production), such as alcohol liver disease (ALD), non-alcoholic non-steatohepatitis (NASH) and atherosclerosis. Experimentally, high titer IgG1 antibody responses are seen after immunization without adjuvant; however, T cell proliferative responses and the role of scavenger receptors in this immunogenicity has not previously been described. In this study, T cell proliferative responses to the carrier protein, but not the MAA hapten itself, were identified in vitro. Moreover, these T proliferative responses were inhibited when MAA-hen egg lysozyme (HEL) was co-immunized with excess scavenger receptor ligand polyG (poly-guanylic acid), implicating the role of (a) scavenger receptor(s) in initiating the T helper cell response. Activated B cells were unable to process and present MAA-HEL preferentially to T cells, while thioglycollate-elicited (but not Con A-elicited) macrophages and dendritic cells (DC) did so with approximately 32-fold less MAA-HEL than native antigen necessary to initiate equal proliferative responses. While this preferential processing and presentation may be related to several factors, preferential binding of MAA haptenated proteins mediated by scavenger receptors may be one mechanism. IL-4 was absent from the supernatants of T proliferative assays despite a strong IgG1 response in vivo, although the TH2 cytokines IL-6 and IL-10 were expressed. Since the modification of proteins by the MAA have previously been shown to occur after ethanol consumption in vivo, the ability of MAA haptens to experimentally enhance immune responses, specifically humoral and T cell responses, may represent mechanisms by which autoimmune phenomena found in ALD occur.

Protection against acetaminophen-induced liver injury and lethality by interleukin 10: role of inducible nitric oxide synthase

Mechanistic study of idiosyncratic drug-induced hepatitis (DIH) continues to be a challenging problem because of the lack of animal models. The inability to produce this type of hepatotoxicity in animals, and its relative rarity in humans, may be linked to the production of anti-inflammatory factors that prevent drug-protein adducts from causing liver injury by immune and nonimmune mechanisms. We tested this hypothesis by using a model of acetaminophen (APAP)-induced liver injury in mice. After APAP treatment, a significant increase was observed in serum levels of interleukin (IL)-4, IL-10, and IL-13, cytokines that regulate inflammatory mediator production and cell-mediated autoimmunity. When IL-10 knockout (KO) mice were treated with APAP, most of these mice died within 24 to 48 hours from liver injury. This increased susceptibility to APAP-induced liver injury appeared to correlate with an elevated expression of liver proinflammatory cytokines, tumor necrosis factor (TNF)-alpha, and IL-1, as well as inducible nitric oxide synthase (iNOS). In this regard, mice lacking both IL-10 and iNOS genes were protected from APAP-induced liver injury and lethality when compared with IL-10 KO mice. All strains, including wild-type animals, generated similar amounts of liver APAP-protein adducts, indicating that the increased susceptibility of IL-10 KO mice to APAP hepatotoxicity was not caused by an enhanced formation of APAP-protein adducts. In conclusion, these findings suggest that an important feature of the normal response to drug-induced liver injury may be the increased expression of anti-inflammatory factors such as IL-10. Certain polymorphisms of these factors may have a role in determining the susceptibility of individuals to idiosyncratic DIH.

Th(1)/Th(2) responses to drugs

T lymphocytes can be characterized by their pattern of cytokine secretion and be divided into type I (Th(l)/Tc(l)) and type 2 (Th(2)/Tc(2)) subsets. The involvement of type-1 or type 2-like responses in sensitization has been studied in the mouse, with reference contact and respiratory contact sensitizers. One interesting feature with certain drugs, such as beta-lactam antibiotics, is the diversity of clinical manifestations associated with immune-mediated hypersensitivity reactions in humans: immediate reactions such as urticaria, Quincke oedema and anaphylactic shock, and delayed hypersensitivity reactions, such as maculopapular rashes, allergic contact dermatitis and skin reactions of other types. In the mouse, Th(1) and Th(2) cytokines have been shown to regulate primary and secondary benzylpenicilloyl- (BPO-) specific antibody responses. Peripheral blood lymphocytes isolated from patients with a clear history of beta-lactam allergy were assessed for type-1 and type-2 phenotypes. Immediate reactions involved mixed Th(1), Tc(1), and Tc(2) responses, whereas allergic contact dermatitis involved Tc(1) and Th(1) cells. Other delayed hypersensitivity reactions to beta-lactams were restricted to Th(1) responses. It has been demonstrated that both CD4(+) and CD8(+)-lidocaine-specific T cell clones isolated from patients with allergic contact dermatitis produced IFN-gamma, even though CD8(+) clones only produce IFN-gamma, while IFN-gamma producing CD4(+) cells concomitantly produced IL-5 and IL-4. Together these data illustrate the heterogeneity of drug-specific T-cell responses.

Il-4 and IFN-gamma mRNA induction in human peripheral lymphocytes specific for beta-lactam antibiotics in immediate or delayed hypersensitivity reactions

Beta-lactam antibiotics elicit CD4+ and CD8+ T-cell-mediated immune responses that play a central role in allergic reactions. However, the involvement of a type 1- (Th1 or Tc1) or a type 2-like (Th2 or Tc2) differentiation in drug allergy remains unclear. We investigated the expression of interleukin 4 (IL-4) and interferon gamma (IFN-gamma) mRNA by quantitative reverse transcription and polymerase chain reaction (RT-PCR) in patient-derived peripheral blood lymphocytes following specific in vitro stimulation. Samples were collected from a total of 19 patients who had developed immediate or delayed clinical manifestations of hypersensitivity to beta-lactam and from 11 control subjects. Peripheral blood mononuclear cells (PBMCs) were stimulated with either free antibiotics or antibiotic-human serum albumin (HSA) conjugates. Specific induction of IFN-gamma mRNA expression was observed in 11 of 11 allergic patients with immediate reactions, in 6 of 8 patients with delayed reactions, and in 4 of 11 control subjects. IL-4 mRNA expression was induced in 5 of 11 allergic individuals with immediate reactions but in none of the 8 patients with delayed responses and none of the 11 control subjects. IL-4 mRNA expression was only induced following activation with free drugs, while IFN-gamma mRNA expression was predominantly induced in CD4+ T cells following stimulation with HSA-conjugated drugs. Immediate-type hypersensitivity to beta-lactams was not associated with a pure type 2-like response when PBMCs were specifically stimulated in vitro: Some patients with well-documented history of beta-lactam-induced immediate allergic reaction showed a high IFN-gamma response. Contact dermatitis involved Tc1 and Th1 cells and other delayed hypersensitivity reactions to beta-lactams were restricted to Th1 responses.

Quantitation of cytokine mRNA expression as an endpoint for prediction and diagnosis of xenobiotic-induced hypersensitivity reactions

Xenobiotic-induced hypersensitivity reactions are immune-mediated effects that involve specific antibodies and/or effector and regulatory T lymphocytes. Cytokines are key mediators of such responses and must be considered as possible endpoints for predicting sensitizing potency of drugs and chemicals, as well as for helping diagnosis of allergy. Detecting cytokine production at the protein level has been shown to not be always sensitive enough. This paper describes three examples of the utilization of semiquantitative or competitive reverse transcription polymerase chain reaction analysis of interleukin-4, interferon gamma, and interleukin-1beta mRNAs as endpoints for assessing T-cell or dendritic cell responses to sensitizing drugs (beta-lactam antibiotics) or chemicals (dinitrochlorobenzene).

Testing strategies in immunotoxicology

Developing a battery of immune function assays to screen potential immunotoxic compounds has been a major issue these past years. Improving this approach is possible using new probes and parameters that are now available from recent knowledge on how the immune system is working (apoptosis, RT-PCR for cytokine mRNA expression). Immunotoxic outcome generally results in serious adverse effects, thus it seems appropriate to evaluate this risk early in drug development. This is especially true in the context of the emerging combinatorial chemistry techniques and high throughput screening in pharmacology resulting in probably numerous molecules to test in toxicology. In this case, screening for adverse effects (genotoxicity, hepatotoxicity, immunotoxicity) that may compromise definitely the development of a molecule should be a help in the decision process since more than one molecule with equivalent pharmacological properties may be available.