No abstract

Summary Cytokines are crucial in host defence against pathogens such as bacteria, viruses, fungi and parasites. A newly described cytokine, interleukin‐32 (IL‐32), induces various proinflammatory cytokines (tumour necrosis factor‐α, IL‐1β, IL‐6) and chemokines in both human and mouse cells through the nuclear factor‐κB and p38 mitogen‐activated protein kinase inflammatory signal pathway. The IL‐32 primarily acts on monocytic cells rather than T cells. In an attempt to isolate the IL‐32 soluble receptor, we used an IL‐32 ligand‐affinity column to purify neutrophil proteinase 3, which is a serine proteinase involved in many inflammatory diseases. IL‐32 has biological activity associated with Mycobacterium tuberculosis and chronic proinflammatory diseases such as rheumatoid arthritis. IL‐32 is transcribed as six alternative splice variants and the biological activity of each individual isoform remains unknown. Here, we cloned the complementary DNA of the four IL‐32 isoforms (α, β, γ and δ) that are the most representative IL‐32 transcripts. To produce recombinant protein with a high yield, the amino acids of two cysteine residues were mutated to serine residues, because serine residues are not conserved among different species. The multi‐step purified recombinant IL‐32 isoform proteins were assessed for their biological activities with different cytokine assays. The γ isoform of IL‐32 was the most active, although all isoforms were biologically active. The present study will provide a specific target to neutralize endogenous IL‐32, which may contribute to basic and clinical immunology.

Inflammatory cytokines mediate inflammatory bowel diseases (IBDs) and cytokine blocking therapies often ameliorate the disease severity. IL-32 affects inflammation by increasing the production of IL-1, TNFα, and several chemokines. Here, we investigated the role of IL-32 in intestinal inflammation by generating a transgenic (TG) mouse expressing human IL-32γ (IL-32γ TG). Although IL-32γ TG mice are healthy, constitutive serum and colonic tissue levels of TNFα are elevated. Compared with wild-type (WT) mice, IL-32γ TG mice exhibited a modestly exacerbated acute inflammation early following the initiation of dextran sodium sulfate (DSS)-induced colitis. However, after 6 d, there was less colonic inflammation, reduced tissue loss, and improved survival rate compared with WT mice. Associated with attenuated tissue damage, colonic levels of TNFα and IL-6 were significantly reduced in the IL-32γ TG mice whereas IL-10 was elevated. Cultured colon explants from IL-32γ TG mice secreted higher levels of IL-10 compared with WT mice and lower levels of TNFα and IL-6. Constitutive levels of IL-32γ itself in colonic tissues were significantly lower following DSS colitis. Although the highest level of serum IL-32γ occurred on day 3 of colitis, IL-32 was below constitutive levels on day 9. The ability of IL-32γ to increase constitutive IL-10 likely reduces TNFα, IL-6, and IL-32 itself accounting for less inflammation. In humans with ulcerative colitis (UC), serum IL-32 is elevated and colonic biopsies contain IL-32 in inflamed tissues but not in uninvolved tissues. Thus IL-32γ emerges as an example of how innate inflammation worsens as well as protects intestinal integrity.

No abstract

Here, we report the development of target-specific binding proteins based on the kringle domain (KD) (∼80 residues), a ubiquitous modular structural unit occurring across eukaryotic species. By exploiting the highly conserved backbone folding by core residues, but using extensive sequence variations in the seven loop regions of naturally occurring human KDs, we generated a synthetic KD library on the yeast cell surface by randomizing 45 residues in the loops of a human KD template. We isolated KD variants that specifically bind to anticancer target proteins, such as human death receptor 4 (DR4) and/or DR5, and that function as agonists to induce apoptotic cell death in several cancer cell lines in vitro and inhibit tumor progression in mouse models. Combined treatments with KD variants possessing different recognition sites on the same target protein exerted synergisitic tumoricidal activities, compared to treatment with individual variants. In addition to the agonists, we isolated an antagonistic KD variant that binds human tumor necrosis factor-α (TNFα) and efficiently neutralizes TNFα-induced cytotoxicity in vitro and in vivo. The KD scaffold with seven flexible loops protruding from the central core was strongly sequence-tolerant to mutations in the loop regions, offering a potential advantage of distinct binding sites for target recognition on the single domain. Our results suggest that the KD scaffold can be used to develop target-specific binding proteins that function as agonists or antagonists toward given target molecules, indicative of their potential use as biotherapeutics.

Background:The maturation process of IL-33 (IL-1F11) remains unclear. Results: IL-33 ligand affinity column isolates neutrophil proteinase 3. Conclusion: PR3 is an IL-33-processing enzyme. Significance: PR3 has a dual function in IL-33 biological activity.

Asthma is a chronic airway inflammatory disease typically associated with T helper cell type 2 (Th2) cytokines. IL-32, first reported as an inducer of tumor necrosis factor (TNF)-α, is an inflammatory cytokine involved in various autoinflammatory diseases, viral infection, and cancer-related inflammation. However, the role of IL-32γ in asthma has not been clearly elucidated. In this study, the levels of IL-32γ in sputum from patients with asthma were measured by ELISA, and IL-32γ function was investigated in murine models of asthma with human IL-32γ-overexpressed transgenic (IL-32γ TG) mice. The therapeutic effect of recombinant IL-32γ (rIL-32γ) on allergic inflammation was also evaluated through bronchoalveolar lavage fluid analysis and histopathologic examinations. Sputum IL-32γ levels from patients with asthma were lower than those from healthy control subjects. In an acute mouse model of asthma, IL-32γ TG mice exhibited significantly reduced airway inflammation compared with that in wild-type mice. The production of Th1 cytokines, such as TNF-α and IFN-γ, and Th2 cytokines, such as IL-4, IL-5, and IL-13, was decreased in the lungs of IL-32γTG mice. On the contrary, the expression of IL-10 and IL-10-producing CD11b(+) monocytic cells was significantly increased in the lungs of ovalbumin-sensitized IL-32γ TG mice. In addition, rIL-32γ treatment revealed a suppressive effect on the airway inflammation in a chronic mouse model of asthma. The results of this study suggest that IL-32γ may have a preventive role in the development of allergic airway inflammation and could be a potential novel therapeutic target for bronchial asthma.

α 1 -Antitrypsin (AAT) is a member of the serine proteinase inhibitor family that impedes the enzymatic activity of serine proteinases, including human neutrophil elastase, cathepsin G and neutrophil proteinase 3. Here, we expressed recombinant AAT by fusing the intact AAT gene to the constant region of IgG1 to generate soluble recombinant AAT-Fc protein. The recombinant AATFc protein was produced in Chinese hamster ovary (CHO) cells and purified using mini-protein A affinity chromatography. Recombinant AAT-Fc protein was tested for antiinflammatory function and AAT-Fc sufficiently suppressed tumor necrosis factor (TNF)-α-induced interleukin (IL)-6 in human peripheral blood mononuclear cells (PBMCs) and inhibited cytokine-induced TNFα by different cytokines in mouse macrophage Raw 264.7 cells. However, AAT-Fc failed to suppress lipopolysaccharide-induced cytokine production in both PBMCs and macrophages. In addition, our data showed that AAT-Fc blocks the development of hyperglycemia in a streptozotocin-induced mouse model of diabetes. Interestingly, we also found that plasma-derived AAT specifically inhibited the enzymatic activity of elastase but that AAT-Fc had no inhibitory effect on elastase activity.