Comparison of IL-1 alpha effectiveness in activating murine pre-B and T cell lines

Expression of Interleukin-1 and Interleukin-1 Receptors Type 1 and Type 2 in Hodgkin Lymphoma

Signaling through the IL-1-receptor type 1 (IL-1R1), IL-1 is required for initiation and maintenance of diverse activities of the immune system. A second receptor, IL-1R2, blocks IL-1 signal transduction. We studied expression of IL-1beta, IL-1R1, and IL-1R2 in 17 Hodgkin lymphomas (HL) by in situ hybridization (ISH). IL-1beta expressing cells, morphologically consistent with endothelial cells and fibroblasts, occurred in all HL tissues with elevated transcript levels in areas of active fibrosis. Hodgkin and Reed-Sternberg (HRS) cells of all cases expressed low IL-1R1 transcript levels in some tumor cells, and high levels of IL-1R2 in large proportions of HRS cells. Only few bystander cells showed low levels of IL-1R1 and IL-1R2 RNA. Supernatants of 4 out of 7 HL-derived cell lines contained soluble IL-1R2 protein at high levels. HL patient sera carried variably amounts of IL-1R2 protein with significantly increased titers in patients with active disease compared to patients in complete remission and control individuals without HL. Western blots and co-immunoprecipitations showed binding of the IL-1R2 to the intracellular IL-1R-accessory protein (IL-1IRAcP). These data suggest functions of the IL-1R2 as a „decoy-receptor” sequestrating paracrine IL-1 extracellularly and intracellularly by engaging IL-1IRAcP, thus depriving IL1-R1 molecules of their extracellular and intracellular ligands. Expression of IL1-R2 by HRS cells seems to contribute to local and systemic modulation of immune function in HL.

Soluble interleukin-1 receptor accessory protein ameliorates collagen-induced arthritis by a different mode of action from that of interleukin-1 receptor antagonist

OBJECTIVE

To discern the mode of interleukin-1 (IL-1) inhibition of soluble IL-1 receptor accessory protein (sIL-1RAcP) by comparison with IL-1 receptor antagonist (IL-1Ra) in arthritis.

METHODS

Adenoviral vectors encoding either sIL-1RAcP or IL-1Ra were administered systemically before onset of collagen-induced arthritis in DBA/1 mice. Anti-bovine type II collagen IgG and IL-6 were quantified in serum. Proliferative response of splenic T cells was determined in the presence of sIL-1RAcP or IL-1Ra. The effect on IL-1 inhibition of recombinant sIL-1RAcP and IL-1Ra was further examined in vitro, using NF-kappaB luciferase reporter cell lines. Quantitative polymerase chain reaction was used to determine the relative messenger RNA expression of the IL-1 receptors.

RESULTS

Adenoviral overexpression of both sIL-1RAcP and IL-1Ra resulted in amelioration of the collagen-induced arthritis. Both IL-1 antagonists reduced the circulating levels of antigen-specific IgG2a antibodies, but only IL-1Ra was able to inhibit lymphocyte proliferation. By using purified lymphocyte populations derived from NF-kappaB reporter mice, we showed that sIL-1RAcP inhibits IL-1-induced NF-kappaB activity in B cells but not T cells, whereas IL-1Ra inhibited IL-1 on both cell types. A study in a panel of NF-kappaB luciferase reporter cells showed that the sIL-1RAcP inhibits IL-1 signaling on cells expressing either low levels of membrane IL-1RAcP or high levels of IL-1RII.

CONCLUSION

We show that the sIL-1RAcP ameliorated experimental arthritis without affecting T cell immunity, in contrast to IL-1Ra. Our results provide data in support of receptor competition by sIL-1RAcP as an explanation for the different mode of IL-1 antagonism in comparison with IL-1Ra.

TNF-alpha dependent NF-kappa B activation in cultured canine keratinocytes is partly mediated by reactive oxygen species

The cytokine TNF-alpha plays a major role in inflammatory and immunological reactions of canine skin. With respect to a possible therapeutic modulation, we investigated the role of the transcription factor NF-kappa B and the involvement of reactive oxygen species (ROS) in the TNF-alpha signalling pathway in cultured canine keratinocytes. TNF-alpha treatment resulted in activation of NF-kappa B which was partially inhibited by the antioxidant alpha-lipoic acid. Using the cytochrome c reduction test no superoxide production could be detected in the supernatant of TNF-alpha stimulated keratinocytes. However, TNF-alpha dependent intracellular hydrogen peroxide production was demonstrated spectroscopically. With electron energy loss spectroscopy (EELS) significant hydrogen peroxide formation was detected in the mitochondria, the endoplasmic reticulum, the cytosol and partially on the plasma membrane of the keratinocytes. Hence, ROS possibly play an important role in the TNF-alpha signalling pathway leading to NF-kappa B activation in canine skin. An adjunctive therapy with natural potent antioxidants modulating NF-kappa B overactivation in canine cutaneous inflammation may be of therapeutic benefit.

Involvement of reactive oxygen species in TNF-alpha mediated activation of the transcription factor NF-kappaB in canine dermal fibroblasts

The cytokine tumor necrosis factor-alpha (TNF-alpha) plays a major role in inflammatory and immune-pathological reactions of the skin. With respect to a possible therapeutic modulation of TNF-alpha mediated activation of Nuclear Factor-kappa B (NF-kappaB) in canine cutaneous inflammation, we investigated the role of NF-kappaB and the involvement of reactive oxygen species (ROS) in the TNF-alpha signalling pathway in dermal fibroblasts of the dog. TNF-alpha treatment resulted in the activation of NF-kappaB as assessed by electrophoretic mobility shift assay (EMSA). Additionally, NF-kappaB translocation was induced with butylhydroperoxide and antimycin A, but not with hydrogen peroxide. TNF-alpha stimulated NF-kappaB activation was partially inhibited by preincubation with the antioxidants alpha-lipoic acid and butylated hydroxyanisol (BHA). No superoxide generation following TNF-alpha stimulation could be detected in the supernatant of canine fibroblasts with the superoxide dismutase-inhibitable cytochrome c reduction test. In contrast, production of TNF-alpha dependent intracellular hydrogen peroxide, the dismutation product of the superoxide radical, was demonstrated spectroscopically by formation of electron dense cerium-hydroperoxide precipitates. With electron energy loss spectroscopy (EELS) significant cerium deposits were detected in the mitochondria, the endoplasmatic reticulum, the cytosol and to a lesser extent on the plasma membrane of canine fibroblasts indicating multiple hydrogen peroxide production sites. Peroxides, therefore, possibly play an important part in the redox-sensitive pathway of TNF-alpha dependent NF-kappaB activation in canine skin. An adjunctive therapy with appropriate antioxidants modulating NF-kappaB overactivation in cutaneous inflammation in the dog is promising.

The interleukin-1 receptor accessory protein (IL-1RAcP) is essential for IL-1-induced activation of interleukin-1 receptor-associated kinase (IRAK) and stress-activated protein kinases (SAP kinases)

Interleukin-1 (IL-1) is a central mediator of the immune system involved in acute and chronic inflammatory responses. Although the sequences of two types of IL-1 receptors are known, the exact molecular events resulting in signal transduction and coupling to downstream signaling elements remain unclear. The recently cloned IL-1 receptor accessory protein (IL-1RAcP) has been suggested as a co-receptor molecule for IL-1RI, supported by the observation that its expression correlates to IL-1 responsiveness. We transfected the EL-4 subline D6/76 with IL-1RAcP cDNA. This cell line is an IL-1 non-responder expressing IL-1RI but lacking constitutive IL-1RAcP expression. The expression of IL-1RAcP in EL-4 D6/76 was sufficient to restore IL-1-induced activation of interleukin-1 receptor-associated kinase and of stress-activated protein kinases, translocation of the transcription factors NFkappaB and IL-1 NF to the nucleus, and induction of IL-2 mRNA synthesis. These results proved that IL-1RAcP is an indispensible molecule in the IL-1 receptor signal transduction complex, necessary to link events on the plasma membrane level to downstream signaling pathways, allowing IL-1-dependent activation of transcription factors and gene expression.

Co-expression of mRNA for type I and type II interleukin-1 receptors and the IL-1 receptor accessory protein correlates to IL-1 responsiveness

Three cell surface molecules participate in Interleukin-1 (IL-1) binding and signal generation, the two distinct types of receptors (type I IL-1R and type II IL-1R) and the IL-1 receptor accessory protein (IL-1RAcP). Low surface expression hampers the detection of all three components on a protein level in most cell types, thus the highly sensitive RT-PCR was used to analyse the mRNA expression in a panel of 18 murine cell types of different hemopoietic lineages and fibroblasts. The transcription of both types of IL-1 receptors was detected in all cell lines tested. In most cell lines the IL-1RAcP was co-expressed with the IL-1 receptors, and only these lines responded to IL-1. However, in three cell lines no mRNA for the IL-1RAcP could be detected, and these cells did not respond to IL-1. These results suggest that the expression of the IL-1RAcP correlates with IL-1 responsiveness and they point to a pivotal role for the IL-1RAcP in IL-1 signal generation.

Activation of a nuclear DNA-binding protein recognized by a transcriptional element, bcn-1, from the laminin B2 chain gene promoter

Treatment of mesangial cells with either phorbol 12-myristate 13-acetate (PMA) or interleukin-1beta induces an increase in laminin B2 chain mRNA levels. In other systems, activation of gene expression by these agents is transcriptionally mediated. To identify transcription factors that control expression of laminin B2 chain gene, we employed a strategy consisting of a computer-based analysis of murine and human gene promoter sequences and gel shift assays. Although overall the laminin B2 chain promoters from the two species have low sequence similarity, the mouse promoter contained sequences that were also contained in one motif, 5'-CCCCGCCCACCTCGCGCGC-3', designated bcn-1, from the human promoter. Treatment of mesangial cells with either PMA or interleukin-1beta induced a transient increase in nuclear DNA binding activity, designated BCN-1, recognized the bcn-1 motif in a gel shift assay. A single nucleotide replacement in the bcn-1 motif abolished DNA binding, indicating that bcn-1.BCN-1 complex formation is highly specific. In transient transfections, the ability of PMA to induce the laminin B2 chain promoter was abolished by mutating the bcn-1 motif. These results suggest that the bcn-1 element and its cognate inducible BCN-1 protein regulate laminin B2 chain gene transcription.

Suppression of experimental arthritis by gene transfer of interleukin 1 receptor antagonist cDNA

Restoration of the impaired balance between pro- and antiinflammatory cytokines should provide effective treatment of rheumatoid arthritis. Gene therapy has been proposed as an approach for delivery of therapeutic proteins to arthritic joints. Here, we examined the efficacy of antiinflammatory gene therapy in bacterial cell wall-induced arthritis in rats. Human secreted interleukin 1 receptor antagonist (sIL-1ra) was expressed in joints of rats with recurrent bacterial cell wall-induced arthritis by using ex vivo gene transfer. To achieve this, primary synoviocytes were transduced in culture with a retroviral vector carrying the sIL-1ra cDNA. Transduced cells were engrafted in ankle joints of animals prior to reactivation of arthritis. Animals in control groups were engrafted with synoviocytes transduced with lacZ and neo marker genes. Cells continued to express transferred genes for at least 9 days after engraftment. We found that gene transfer of sIL-1ra significantly suppressed the severity of recurrence of arthritis, as assessed by measuring joint swelling and by the gross-observation score, and attenuated but did not abolish erosion of cartilage and bone. The effect of intraarticularly expressed sIL-1ra was essentially local, as there was no significant difference in severity of recurrence between unengrafted contralateral joints in control and experimental groups. We estimate that locally expressed sIL-1ra was about four orders of magnitude more therapeutically efficient than systemically administered recombinant sIL-1ra protein. These findings provide experimental evidence for the feasibility of antiinflammatory gene therapy for arthritis.