Cytokines in clinical and experimental transplantation

The design and synthesis of novel orally active inhibitors of AP-1 and NF-κB mediated transcriptional activation. SAR of In vitro and In vivo studies

We have developed novel orally active quinazoline analogues as inhibitors of AP-1 and NF-kappaB mediated transcriptional activation. Among the derivatives prepared, 1-[2-(2-thienyl)quinazolin-4-ylamino]-3-methyl-3-pyrroline-2,5-dione (10) showed significant activity in an adjuvant-induced arthritis rat model by reducing the swelling by 65% in the non-injected foot. The synthesis, structure-activity relationship, and in vivo activity are described.

Structure-activity relationships of 6-fluoroquinazolines: dual-acting compounds with inhibitory activities toward both TNF-alpha production and T cell proliferation

We synthesized various 6-fluoro-7-(1-piperazino)quinazolines based on the structure of 1 and evaluated their inhibitory activities toward both TNF-alpha production and T cell proliferation responses. Among these compounds, 7a, having the 3,4-(methylenedioxy)phenyl moiety at the C(4)-position of the quinazoline ring, showed both inhibitory activities. Furthermore, the oral treatment with 7a exhibited an anti-inflammatory effect in rats with adjuvant arthritis as well as an inhibitory activity toward LPS-induced TNF-alpha production.

Discovery of quinazolines as a novel structural class of potent inhibitors of NF-kappa B activation

We disclose here a new structural class of low-molecular-weight inhibitors of NF-kappa B activation that were designed and synthesized by starting from quinazoline derivative 6a. Structure-activity relationship (SAR) studies based on 6a elucidated the structural requirements essential for the inhibitory activity toward NF-kappa B transcriptional activation, and led to the identification of the 6-amino-4-phenethylaminoquinazoline skeleton as the basic framework. In this series of compounds, 11q, containing the 4-phenoxyphenethyl moiety at the C(4)-position, showed strong inhibitory effects on both NF-kappa B transcriptional activation and TNF-alpha production. Furthermore, 11q exhibited an anti-inflammatory effect on carrageenin-induced paw edema in rats.

Structure-activity relationship studies of ethyl 2-[(3-methyl-2,5-dioxo(3-pyrrolinyl))amino]-4-(trifluoromethyl)pyrimidine-5-carboxylate: an inhibitor of AP-1 and NF-kappaB mediated gene expression

Several analogues of ethyl 2-[(3-methyl-2,5-dioxo(3-pyrrolinyl))amino]-4-(trifluoromethyl)pyrimidine-5-carboxylate (1) were synthesized and tested as inhibitors of AP-1 and NF-kappaB mediated transcriptional activation in Jurkat T cells. From our SAR work, ethyl 2-[(3-methyl-2,5-dioxo(3-pyrrolinyl))-N-methylamino]-4-(trifluoromethyl)-pyrimidine-5-carboxylate was identified as a novel and potent inhibitor.

Inhibitors of NF-kappaB and AP-1 gene expression: SAR studies on the pyrimidine portion of 2-chloro-4-trifluoromethylpyrimidine-5-[N-(3', 5'-bis(trifluoromethyl)phenyl)carboxamide]

We investigated the structure-activity relationship studies of N-[3, 5-bis(trifluoromethyl)phenyl][2-chloro-4-(trifluoromethyl)pyrimidin-5 -yl]carboxamide (1), an inhibitor of transcription mediated by both NF-kappaB and AP-1 transcription factors, with the goal of improving its potential oral bioavailability. Compounds were examined for cell-based activity, were fit to Lipinski's rule of 5, and were examined for potential gastrointestinal permeability using the intestinal epithelial cell line, Caco-2. Selected groups were substituted at the 2-, 4-, and 5-positions of the pyrimidine ring using solution-phase combinatorial methodology. The introduction of a fluorine in the place of 2-chlorine of 1 resulted in a compound with comparable activity. However, other substitutions at the 2-position resulted in a loss of activity. The trifluoromethyl group at the 4-position could be replaced with a methyl, ethyl, chlorine, or phenyl without a substantial loss of activity. The carboxamide group at the 5-position is critical for activity. If it was moved to the 6-position, the activity was lost. The 2-methyl analogue of 1 (81) showed comparable in vitro activity and improved Caco-2 permeability compared to 1.

Novel inhibitors of AP-1 and NF-kappaB mediated gene expression: structure-activity relationship studies of ethyl 4-[(3-methyl-2,5-dioxo(3-pyrrolinyl))amino]-2-(trifluoromethyl)++ +pyrimidi ne-5-carboxylate

In an effort to identify novel inhibitors of AP-1 and NF-kappaB mediated transcriptional activation, several analogues of ethyl 4-[(3-methyl-2,5-dioxo(3-pyrrolinyl))amino]-2-(trifluoromethyl)pyr imidine-5-carboxylate (1) were synthesized and tested in two in vitro assays. The 2-(2'-thienyl) substituted compound (11) was identified as the most potent in this series.

Donor-specific stimulation of peripheral blood mononuclear cells from recipients of orthotopic liver transplants is associated, in the absence of rejection, with type-2 cytokine production

In this study, we examined the cytokine production by human peripheral blood mononuclear cells (PBM) from recipients of orthotopic liver transplants which had been stimulated by donor-specific alloantigen. Levels of interleukin (IL)-2, IL-4, interferon (IFN)-gamma, IL-10 and transforming growth factor (TGF)-beta produced in vitro from PBM of 15 transplant recipients at 5-7 months post transplantation were analysed after donor-specific, third-party, or non-specific stimulation. Mononuclear cell proliferation in response to stimulation and cytokine mRNA from the cell cultures were assayed. Donor-specific antigen was obtained from donor spleen cells which had been obtained and frozen in liquid nitrogen at the time of organ retrieval. Third-party restimulation used equivalent numbers of spleen cells pooled from the other 14 organ donors. Cytokine production was correlated with the clinical condition of the patient, including biopsy results when available, and biochemical data. The data show a highly significant correlation between the donor-specific- and third-party- stimulated IL-4 and IL-10 production from recipient PBM with stable liver graft function as assessed by histopathology and/or biochemistry. This correlation was independent of level of immunosuppression. These data strongly support a role for IL-4 and/or IL-10 in the induction and/or maintenance of tolerance to human liver allografts. Measurement of the levels of these cytokines from recipient PBM after donor-specific antigen stimulation in vitro may be a useful test for monitoring for acute allograft rejection.

2-Chloro-4-(trifluoromethyl)pyrimidine-5-N-(3',5'- bis(trifluoromethyl)phenyl)-carboxamide: a potent inhibitor of NF-kappa B- and AP-1-mediated gene expression identified using solution-phase combinatorial chemistry

Described is the identification of a novel series of compounds that blocks the activation of two key transcription factors, AP-1 and NF-kappa B. These transcription factors regulate the expression of several critical proinflammatory proteins and cytokines and represent attractive targets for drug discovery. Through the use of high throughput screening and solution-phase parallel synthesis, inhibitors of both NF-kappa B and AP-1 were identified. In subsequent testing, these compounds were also shown to block both IL-2 and IL-8 levels in the same cells. One of the most potent compounds in this series, 28, was active in several animal models of inflammation and immunosuppression, thus validating the importance of AP-1 and NF-kappa B as potential therapeutic targets. The synthesis and preliminary structure-activity relationships of these compounds is addressed.

CD4+ cells proliferate after peanut-extract-specific and CD8+ cells proliferate after polyclonal stimulation of PBMC of children with atopic dermatitis

BACKGROUND

Few studies describe in vitro food-allergen induced proliferative responses and cytokine production of PBMC of children with atopic dermatitis. This is especially true for peanut-allergen.

OBJECTIVES

To analyse the specificity of the T cell in proliferative responses, in children with atopic dermatitis with or without peanut allergy and healthy age-matched children.

METHODS

Proliferative responses were measured by [3H]-thymidine incorporation and by expression of the intracellular Ki67-antigen using flow cytometry after antigen-specific stimulation of PBMC with peanut-extract (day 7) or polyclonal stimulation with Phorbol-12myristate-13acetate and Ca-ionophore (day 3). Cytokine mRNA (Interferon-gamma (IFNgamma), IL-4) was detected by semiquantitative RT-PCR. Cytokine production (IL-4, IFNgamma) was measured by ELISA.

RESULTS

Peanut-extract induced proliferative responses of PBMC from children with atopic dermatitis and peanut allergy (AD+PA+) were significantly higher as compared with the other groups studied. Ki67-antigen double staining revealed that 80-100% of the proliferating cells were CD4+. These proliferative responses correlated significantly with the increase in IL-4 mRNA expression after peanut-extract specific stimulation. After polyclonal stimulation, however, CD8+ cells preferentially proliferated. The degree of proliferation after polyclonal stimulation correlated inversely with the ratio of IL-4/IFNgamma production.

CONCLUSIONS

The principal responding population of T cells in proliferative responses is different after peanut-extract specific and polyclonal stimulation of PBMC from AD+PA+ patients. Furthermore, we found indirect evidence that the PBMC fraction of AD+PA+ children contains increased frequencies of peanut-specific T helper-2 cells.

Type 1 and type 2 cytokine dysregulation in human infectious, neoplastic, and inflammatory diseases

In the mid-1980s, Mosmann, Coffman, and their colleagues discovered that murine CD4+ helper T-cell clones could be distinguished by the cytokines they synthesized. The isolation of human Th1 and Th2 clones by Romagnani and coworkers in the early 1990s has led to a large number of reports on the effects of Th1 and Th2 on the human immune system. More recently, cells other than CD4+ T cells, including CD8+ T cells, monocytes, NK cells, B cells, eosinophils, mast cells, basophils, and other cells, have been shown to be capable of producing "Th1" and "Th2" cytokines. In this review, we examine the literature on human diseases, using the nomenclature of type 1 (Th1-like) and type 2 (Th2-like) cytokines, which includes all cell types producing these cytokines rather than only CD4+ T cells. Type 1 cytokines include interleukin-2 (IL-2), gamma interferon, IL-12 and tumor necrosis factor beta, while type 2 cytokines include IL-4, IL-5, IL-6, IL-10, and IL-13. In general, type 1 cytokines favor the development of a strong cellular immune response whereas type 2 cytokines favor a strong humoral immune response. Some of these type 1 and type 2 cytokines are cross-regulatory. For example, gamma interferon and IL-12 decrease the levels of type 2 cytokines whereas IL-4 and IL-10 decrease the levels of type 1 cytokines. We use this cytokine perspective to examine human diseases including infections due to viruses, bacteria, parasites, and fungi, as well as selected neoplastic, atopic, rheumatologic, autoimmune, and idiopathic-inflammatory conditions. Clinically, type 1 cytokine-predominant responses should be suspected in any delayed-type hypersensitivity-like granulomatous reactions and in infections with intracellular pathogens, whereas conditions involving hypergammaglobulinemia, increased immunoglobulin E levels, and/or eosinophilia are suggestive of type 2 cytokine-predominant conditions. If this immunologic concept is relevant to human diseases, the potential exists for novel cytokine-based therapies and novel cytokine-directed preventive vaccines for such diseases.

Lymphokine release during co-culture of human lympho-mononuclear cells and fresh or cultured human, porcine and bovine pancreatic islets

In this study we evaluated whether isolated human (HI), porcine (PI) and bovine (BI) islets, either fresh (Fr) or cultured for 4 weeks (4 w) affect cytokine release from human lymphomononuclear cells (LMC) differently. We prepared LMC from peripheral blood by density gradient purification and co-cultured 1 x 10(6) LMC for 24 h with 100 hand-picked islets, either within 48 h of isolation or after culture for 4 weeks. Soluble interleukin-2 receptor (IL-2R), interferon-gamma (IFN), interleukin-4 (IL-4) and interleukin-10 (IL-10) were measured by sandwich enzyme-linked immunoadsorbent assay. Compared with controls (Ctrl, LMC without islets), Fr-HI, Fr-PI and Fr-BI caused a similar increase of IL-2R and IFN release, whereas 4 w-HI and 4 w-BI did not lead to any significant production of these two cytokines. IL-10 concentrations increased with Fr-PI and Fr-BI, but not with Fr-HI, and no major effect of the 4-week culture was seen. IL-4 levels were below the detection limit of the method used in these experiments. Thus, fresh allo- and xeno-islets caused a similar increase of the release of cytokines known to be markers of Th1 activation, whereas the release of IL-10, a marker of Th2 activation, increased with xeno-, but not with allo-islets; culturing the islets for 4 weeks decreased Th1, but not Th2 activation.