Raffaella Faggioni

IL-18-Binding Protein Protects Against Lipopolysaccharide- Induced Lethality and Prevents the Development of Fas/Fas Ligand-Mediated Models of Liver Disease in Mice

IL-18-binding protein (IL-18BP) is a natural IL-18 inhibitor. Human IL-18BP isoform a was produced as fusion construct with human IgG1 Fc and assessed for binding and neutralizing IL-18. IL-18BP-Fc binds human, mouse, and rat IL-18 with high affinity (KD 0.3–5 nM) in a BIAcore-based assay. In vitro, IL-18BP-Fc blocks IL-18 (100 ng/ml)-induced IFN-γ production by KG1 cells (EC50 = 0.3 μg/ml). In mice challenged with an LD90 of LPS (15 mg/kg), IL-18BP-Fc (5 mg/kg) administered 10 min before LPS blocks IFN-γ production and protects against lethality. IL-18BP-Fc administered 10 min before LPS blocks IFN-γ production induced by LPS (5 mg/kg) with ED50 of 0.005 mg/kg. Furthermore, IL-18BP-Fc (5 mg/kg) abrogates LPS (5 mg/kg)-induced IFN-γ production even when administered 6 days before LPS but shows no effect when administered 9 or 12 days before LPS. Given 10 min before LPS challenge to mice primed 12 days in advance with heat-killed Propionibacterium acnes, IL-18BP-Fc prevents LPS-induced liver damage and IFN-γ and Fas ligand expression. Given at the moment of priming with P. acnes, IL-18BP-Fc decreases P. acnes-induced granuloma formation, macrophage-inflammatory protein-1α and macrophage-inflammatory protein-2 production and prevents sensitization to LPS. IL-18BP-Fc also prevents Con A-induced liver damage and IFN-γ and Fas ligand expression as well as liver damage induced by Pseudomonas aeruginosa exotoxin A or by anti-Fas agonistic Ab. In conclusion, IL-18BP can be engineered and produced in recombinant form to generate an IL-18 inhibitor, IL-18BP-Fc, endowed with remarkable in vitro and in vivo properties of binding and neutralizing IL-18.

Leptin deficiency, not obesity, protects mice from Con A-induced hepatitis.

Leptin‐deficient ob/ob mice are protected from Conu2004A‐induced hepatitis. However, it is unclear whether leptin deficiency or obesity itself is responsible for this protection. To address this question, wild‐type (WT) obese mice with high serum leptin levels were generated by injection of gold thioglucose (WT GTG). Both Conu2004A‐injected WT and WT GTG mice developed hepatitis, whereas no hepatic damage was observed in ob/ob mice. Moreover, TNF‐α and IFN‐γ levels as well as expression of the activation marker CD69 were elevated in liver mononuclear cells of WT and WT GTG mice, but not in ob/ob mice following administration of Conu2004A. The liver of WT and WT GTG mice had the same percentage of NK T cells, a lymphocyte population involved in Conu2004A‐induced hepatitis. This population decreased equally in both WT and WT GTG mice after Conu2004A injection. In contrast, the liver of ob/ob mice contained 50% less NK T cells compared to WT and WT GTG mice. Furthermore, no decrease in NK T cells was observed in Conu2004A‐injected ob/ob mice. We conclude that leptin‐deficiency, not obesity, is responsible for protection from Conu2004A‐induced hepatitis.

PK-PD modeling of protein drugs: implications in assay development

Pharmacokinetic-pharmacodynamic (PK-PD) modeling is an integral part of the preclinical and clinical development of protein drugs. Bioanalytical data from appropriately selected and well-characterized PK and PD biomarker assays can be incorporated into mechanistic PK-PD models and allow a quantitative relationship between protein drug exposure, target modulation, and biochemical, physiological and pathophysiological effects to be established. The selection of PD biomarkers that assess target engagement and modulation in the extracellular milieu and downstream cellular effects can provide proof-of-mechanism and define the magnitude and duration of target modulation following drug administration. The PK-PD data can provide an important link between magnitude of target modulation and clinical efficacy and safety outcomes, and guide the selection of doses and dosing schedules for clinical trials. In this article, approaches to the selection and development of fit-for-purpose, PK and PD assays for protein drugs are reviewed, and the applications of the assay results in PK-PD models are discussed.

Regulatory Effects of Novel Neurotrophin-1/B Cell-Stimulating Factor-3 (Cardiotrophin-Like Cytokine) on B Cell Function

We describe regulatory effects that a novel neurotrophin-1/B cell-stimulating factor-3 (NNT-1/BSF-3; also reported as cardiotrophin-like cytokine) has on B cell function. NNT-1/BSF-3 stimulates B cell proliferation and Ig production in vitro. NNT-1/BSF-3-transgenic mice, engineered to express NNT-1/BSF-3 in the liver under control of the apolipoprotein E promoter, show B cell hyperplasia with particular expansion of the mature follicular B cell subset in the spleen and the prominent presence of plasma cells. NNT-1/BSF-3-transgenic mice show high serum levels of IgM, IgE, IgG2b, IgG3, anti-dsDNA Abs, and serum amyloid A. NNT-1/BSF-3-transgenic mice also show non-amyloid mesangial deposits that contain IgM, IgG, and C3 and are characterized by a distinctive ultrastructure similar to that of immunotactoid glomerulopathy. NNT-1/BSF-3-transgenic mice produce high amounts of Ag-specific IgM, IgA, and IgE and low amounts of IgG2a and IgG3. Normal mice treated with NNT-1/BSF-3 also produce high amounts of Ag-specific IgE. NNT-1/BSF-3 regulates immunity by stimulating B cell function and Ab production, with preference for Th2 over Th1 Ig types.