Interleukin 7 stimulates tumour necrosis factor alpha and Th1 cytokine production in joints of patients with rheumatoid arthritis

Circulating cytokine profiles and their relationships with autoantibodies, acute phase reactants, and disease activity in patients with rheumatoid arthritis

Our objective was to analyse the relationship between circulating cytokines, autoantibodies, acute phase reactants, and disease activity in DMARDs-naïve rheumatoid arthritis (RA) patients (n = 140). All cytokines were significantly higher in the RA cohort than in healthy controls. Moderate-to-strong positive intercorrelations were observed between Th1/Th2/macrophage/fibroblast-derived cytokines. RF correlated significantly with IL-1β, IL-2, IL-4, IL-10, IL-12, G-CSF, GM-CSF, IFN-γ, and TNF (P < .0001), and aCCP and aMCV with IL-1β, IL-2, IL-4, and IL-10 (P < .0002), while IL-6 correlated best with the acute phase reactants, CRP, and SAA (P < .0001). In patients with a DAS28 score of ≥5.1, IFN-γ, IL-1β, IL-1Ra, TNF, GM-CSF, and VEGF were significantly correlated (P < .04–.001) with high disease activity (HDA). Circulating cytokines in RA reflect a multifaceted increase in immune reactivity encompassing Th1 and Th2 cells, monocytes/macrophages, and synovial fibroblasts, underscored by strong correlations between these cytokines, as well as their relationships with RF, aCCP, and aMCV, with some cytokines showing promise as biomarkers of HDA.

Differential expression of immune-associated cancer regulatory genes in low- versus high-dose-rate irradiated AKR/J mice

AKR/J mice carrying leukemia viral inserts develop thymic lymphoma. Recently, we demonstrated that the incidence of thymic lymphoma was decreased when these mice were raised in a low-dose-rate γ-irradiation facility. In contrast, mice irradiated at a high-dose rate developed severe thymic lymphoma and died much earlier. To understand the genetic changes occurred by low- versus high-dose-rate γ-irradiation whole genome microarray was performed. Both groups of mice demonstrated up-regulation of Ifng, Igbp1, and IL7 in their thymuses, however, mice exposed to high-dose-rate γ-irradiation exhibited marked down-regulation of Sp3, Il15, Traf6, IL2ra, Pik3r1, and Hells. In contrast, low-dose-rate irradiated mice demonstrated up-regulation of Il15 and Jag2. These gene expression profiles imply the impaired immune signaling pathways by high-dose-rate γ-irradiation while the facilitation of anti-tumor immune responses by low-dose-rate γ-irradiation. Therefore, our data delineate common and distinct immune-associated pathways downstream of low- versus high-dose-rate irradiation in the process of cancer progression in AKR/J mice.

Blockade of the interleukin-7 receptor inhibits collagen-induced arthritis and is associated with reduction of T cell activity and proinflammatory mediators

OBJECTIVE

To study the effects of interleukin-7 receptor α-chain (IL-7Rα) blockade on collagen-induced arthritis (CIA) and to investigate the effects on T cell numbers, T cell activity, and levels of proinflammatory mediators.

METHODS

We studied the effect of anti-IL-7Rα antibody treatment on inflammation and joint destruction in CIA in mice. Numbers of thymocytes, splenocytes, T cell subsets, B cells, macrophages, and dendritic cells were assessed. Cytokines indicative of Th1, Th2, and Th17 activity and several proinflammatory mediators were assessed by multianalyte profiling in paw lysates. In addition, T cell-associated cytokines were measured in supernatants of lymph node cell cultures.

RESULTS

Anti-IL-7Rα treatment significantly reduced clinical arthritis severity in association with reduced radiographic joint damage. Both thymic and splenic cellularity were reduced after treatment with anti-IL-7Rα. IL-7Rα blockade specifically reduced the total number of cells as well as numbers of naive, memory, CD4+, and CD8+ T cells from the spleen and significantly reduced T cell-associated cytokines (interferon-γ, IL-5, and IL-17). IL-7Rα blockade also decreased local levels of proinflammatory cytokines and factors associated with tissue destruction, including tumor necrosis factor α, IL-1β, IL-6, matrix metalloproteinase 9, and RANKL. IL-7Rα blockade did not significantly affect B cells, macrophages, and dendritic cells. B cell activity, indicated by serum anticollagen IgG antibodies, was not significantly altered.

CONCLUSION

Blockade of IL-7Rα potently inhibited joint inflammation and destruction in association with specific reductions of T cell numbers, T cell-associated cytokines, and numerous mediators that induce inflammation and tissue destruction. This study demonstrates an important role of IL-7R-driven immunity in experimental arthritis and indicates the therapeutic potential of IL-7Rα blockade in human arthritic conditions.

IL-7Rα confers susceptibility to experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a neurological disorder that causes paralysis in young adults and affects women more frequently than men. The etiology of MS is not known, but it is generally viewed as an autoimmune disease of the central nervous system (CNS), influenced by genetic and environmental factors. Recent studies have identified interleukin-7 receptor α (IL-7Rα) as a risk factor for MS. But the role of IL-7Rα in experimental autoimmune encephalomyelitis (EAE) model of MS is not known. In this study we demonstrate that IL-7Rα-deficient (IL-7Rα(-/-)) mice remain resistant to MOGp35-55-induced EAE. When compared with C57BL/6 wild-type mice, IL-7Rα(-/-) mice showed less severe inflammation and demyelination in the CNS. The attenuation of EAE in IL-7Rα(-/-) mice was associated with a decrease in T-helper (Th) 1 and Th17 responses in the CNS and lymphoid organs. IL-7Rα(-/-) mice also showed an increase in Th2 response and CD4(+)Foxp3(+) regulatory T cells. These findings highlight that IL-7Rα confers susceptibility by influencing autoimmune Th1/Th17 responses in EAE model of MS.

IL-7 and lymphopenia

Interleukin-7 (IL-7) is a growth and anti-apoptotic factor for T-lymphocytes, with potential for clinical use in the treatment of immunodeficiencies due to loss of T-cells. Lymphopenia induced by disease (HIV infection, hemodialysis or Idiopathic CD4+ lymphopenia) or by treatment (high dose chemotherapy or depleting antibodies) for cancer or auto-immune diseases results in increased circulating levels of IL-7 which decline with T-cell recovery, however, the mechanism of such response remains to be elucidated. Furthermore, IL-7 is a major player in the regulation of peripheral T-cell homeostasis and as such is an important candidate cytokine for therapy aimed at improving T-cell reconstitution following lymphopenia. Anti- IL-7 is on the other hand proposed to treat conditions where IL-7 may play a more direct role in pathogenesis such as autoimmune disease like Rheumatoid Arthritis, Multiple Sclerosis or Inflammatory Bowel disease.

Increased expression of interleukin-7 in labial salivary glands of patients with primary Sjögren's syndrome correlates with increased inflammation

OBJECTIVE

To study the expression levels and immunostimulatory capacities of interleukin-7 (IL-7) in primary Sjögren's syndrome.

METHODS

Labial salivary gland (LSG) IL-7 expression was determined by immunohistochemistry, using a quantitative scoring system, in 30 patients with sicca syndrome: 15 patients with primary Sjögren's syndrome (SS) and 15 patients with non-SS sicca syndrome. The correlation of IL-7 expression in LSGs with parameters of local and peripheral disease was studied, and serum and salivary IL-7 levels were determined. Additionally, the effects of IL-7 on cytokine production by peripheral blood mononuclear cells (PBMCs) from patients with primary SS were determined in vitro by Luminex multicytokine assay and compared with the effects in control subjects.

RESULTS

The expression of IL-7 in LSGs was higher in patients with primary SS compared with that in patients with non-SS sicca syndrome. IL-7 was observed primarily in the vicinity of lymphocytic infiltrates. Salivary IL-7 levels in patients with primary SS were higher than those in control subjects. In all 30 patients with sicca syndrome, IL-7 expression in LSGs correlated with parameters of both local and peripheral disease. Furthermore, IL-7 stimulated T cell-attracting and T cell-differentiating cytokines (monokine induced by interferon-gamma [IFNgamma], IFNgamma-inducible 10-kd protein, IL-12, and IL-15), as well as Th1 (IFNgamma), Th2 (IL-4), Th17 (IL-17A), proinflammatory (tumor necrosis factor alpha and IL-1alpha), and regulatory (IL-10 and IL-13) cytokine production by PBMCs. All of these cytokines were previously shown to be associated with primary SS. The IL-7-induced increase in IL-10 production in patients with primary SS was reduced compared with that in control subjects.

CONCLUSION

The correlation between LSG IL-7 expression and (local) disease parameters in primary SS as well as the IL-7-mediated induction of inflammatory cytokines indicate that IL-7 might contribute to the immunopathology of primary SS.

Elevated expression of interleukin-7 receptor in inflamed joints mediates interleukin-7-induced immune activation in rheumatoid arthritis

OBJECTIVE

To evaluate the expression and functional ability of the high-affinity interleukin-7 receptor (IL-7Ralpha) in patients with rheumatoid arthritis (RA).

METHODS

Expression of IL-7Ralpha and IL-7 was determined in synovial tissue from RA patients and was compared with that in synovial tissue from patients with undifferentiated arthritis (UA) and osteoarthritis (OA). IL-7Ralpha expression on CD4 T cells, CD19 B cells, and CD14 monocyte/macrophages from RA synovial tissue, synovial fluid, and peripheral blood was also assessed. The proliferative capacity of IL-7Ralpha(bright) and IL-7Ralpha(dim/-) T cells was measured. In addition, we examined IL-7R blockade with soluble human IL-7Ralpha (hIL-7Ralpha) in the prevention of immune activation of peripheral blood mononuclear cells.

RESULTS

We found significantly higher IL-7Ralpha expression in RA and UA synovial tissue than in OA synovial tissue, and the level of IL-7Ralpha expression correlated significantly with the levels of CD3 and IL-7 expression. CD4 T cells from RA synovial fluid and synovial tissue strongly expressed IL-7Ralpha. A substantial percentage of B cells and macrophages from RA synovial fluid and synovial tissue also expressed IL-7Ralpha, although less prominently than T cells. We found that peripheral blood IL-7Ralpha(bright) T cells that did not express FoxP3 were highly proliferative as compared with IL-7Ralpha(dim/-) T cells that did express high levels of FoxP3. Soluble hIL-7Ralpha inhibited IL-7-induced proliferation and interferon-gamma production by mononuclear cells from RA patients.

CONCLUSION

Our data suggest that enhanced expression of IL-7Ralpha and IL-7 in RA patients contributes significantly to the joint inflammation by activating T cells, B cells, and macrophages. The inhibition of IL-7R-mediated immune activation by soluble hIL-7Ralpha further indicates an important role of IL-7Ralpha in inflammatory responses in RA, suggesting IL-7Ralpha as a therapeutic target for immunotherapy in RA.

Variation in the IL7RA and IL2RA genes in German multiple sclerosis patients

Variation in the genes encoding the interleukin (IL) 7 and IL2 receptor alpha chains (IL7RA, IL2RA) was recently found associated with multiple sclerosis (MS). We evaluated the role of these two genes in a large German MS case-control cohort. Five single nucleotide polymorphisms (SNPs) in IL7RA and four in IL2RA were genotyped in 1319 MS patients and 908 controls by means of restriction enzyme digestion or TaqMan assays and subsequently evaluated for association with MS. IL7RA expression was measured via quantitative real time PCR in 24 subjects. We replicated the association of exon 6 variation (rs6897932) in IL7RA with MS. Yet, this association was only found in patients with primary progressive (pp) or secondary progressive (sp) disease course (p=0.0004). Expression analysis did not show differences in IL7RA expression depending on genotypes at this locus, while reduced expression of the soluble receptor was observed in patients with pp and sp MS irrespective of genotype. In the IL2RA gene, significant associations of SNPs in introns 3 and 7 with MS subtypes were obvious. Together these results confirm involvement of polymorphisms in the IL7RA and IL2RA genes in MS pathogenesis and suggest that IL7RA variation may primarily affect chronic disease courses.

Identification of interleukin-7 as a candidate disease mediator in spondylarthritis

OBJECTIVE

Understanding of the molecular pathophysiology of spondylarthritis (SpA) remains largely elusive. This is related both to the complexity of the disease (axial versus peripheral disease, inflammation versus tissue remodeling) and to the difficulty in obtaining samples from primary disease sites. This study was undertaken to explore a gene expression approach for identifying novel candidate mediators of SpA.

METHODS

Sacroiliac joint fluid aspirates from 3 SpA patients with active sacroiliitis were studied by microarray analysis. The expression of selected candidate molecules in peripheral synovitis was confirmed by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Microarray analysis identified 4 sacroiliitis gene clusters, containing a total of 47 messenger RNA (mRNA) transcripts. Two clusters contained genes expressed in all sacroiliitis samples, corresponding to both known and unsuspected candidate mediators of SpA pathology. These included proinflammatory molecules as well as molecules involved in tissue remodeling, such as transforming growth factor beta2. Of the novel candidate genes selected for confirmation, interleukin-7 (IL-7) mRNA expression was higher in SpA peripheral synovial fluid and synovial tissue samples than in osteoarthritis samples, and similar to expression in rheumatoid arthritis (RA) samples. At the protein level, synovial fluid IL-7 levels were even higher in SpA than in RA, despite lower levels of tumor necrosis factor alpha and IL-1beta.

CONCLUSION

In the present study, both known and unsuspected candidate mediators of SpA pathogenesis were identified, including IL-7. The specific overexpression of IL-7 at sites of peripheral synovitis in SpA suggests that further functional investigations of the role of this cytokine in SpA pathogenesis are warranted.

Reduced CD4+,CD25- T cell sensitivity to the suppressive function of CD4+,CD25high,CD127 -/low regulatory T cells in patients with active systemic lupus erythematosus

OBJECTIVE

CD4+,CD25high regulatory T (Treg) cells play a crucial role in the maintenance of self tolerance and prevention of organ-specific autoimmunity. The presence of many in vivo-preactivated CD4+,CD25++ T cells in patients with systemic lupus erythematosus (SLE) poses a difficulty in discriminating CD25++ activated T cells from CD25high Treg cells. To overcome this problem, we analyzed the phenotype and function of CD4+,CD25high,CD127(-/low) natural Treg (nTreg) cells isolated from the peripheral blood of patients with SLE.

METHODS

CD4+,CD25high,CD127(-/low) nTreg cells and CD4+,CD25- responder T (Tresp) cells from patients with SLE and normal donors were separated by fluorescence-activated cell sorting. Cell proliferation was quantified by 3H-thymidine incorporation, and immunophenotyping of the cells was done using FACScan.

RESULTS

Comparable percentages of CD4+,CD25high,FoxP3+ T cells were observed in patients with SLE and normal donors. Proliferation of SLE nTreg cells sorted into the subset CD4+,CD25high,CD127(-/low) was significantly decreased compared with that of SLE nTreg cells sorted into the subset CD4+,CD25high (mean +/- SEM 2,223 +/- 351 counts per minute versus 9,104 +/- 1,720 cpm, respectively), while in normal donors, these values were 802 +/- 177 cpm and 2,028 +/- 548 cpm, respectively, confirming that effector cell contamination was reduced. Notably, the suppressive activity of nTreg cells was intact in all groups. However, CD4+,CD25- Tresp cells isolated from patients with active SLE were significantly less sensitive than those from patients with inactive SLE to the suppressive function of autologous or normal donor CD4+,CD25high,CD127(-/low) nTreg cells. Furthermore, a significant inverse correlation was observed between the extent of T cell regulation in suppressor assays and the level of lupus disease activity.

CONCLUSION

This study is the first to show that, in human SLE, impaired sensitivity of Tresp cells to the suppressive effects of a comparably functional, highly purified nTreg cell population leads to a defective suppression of T cell proliferation in active SLE. Studies aiming to define the mechanisms leading to Tresp cell resistance might help in the development of highly specific, alternative immunotherapeutic tools for the control of systemic autoimmune diseases such as SLE.

Alpha1beta1 integrin and interleukin-7 receptor up-regulate the expression of RANKL in human T cells and enhance their osteoclastogenic function

Activated T cells, through the production of the receptor activator of NF-kappaB ligand (RANKL) cytokine, have been implicated in the osteoclast development and bone loss that are associated with autoimmune diseases such as rheumatoid arthritis. However, the cellular pathways that regulate the expression of RANKL and the induction of osteoclasts are still unclear. In this study, we show that, in human effector CD4(+) T cells, activation of alpha1beta1 integrin and interleukin (IL)-7 receptor (IL-7R) up-regulates the expression and production of RANKL but has no effect on the production of interferon-gamma, an inhibitor of T-cell-mediated osteoclastogenesis. Thus, both alpha1beta1 integrin and IL-7R enhance the ability of these cells to induce the formation of osteoclasts from human monocytes. Furthermore, we found that simultaneous activation of effector CD4(+) T cells via alpha1beta1 integrin and IL-7R synergistically increases the production of RANKL and enhances their osteoclastogenic function. We also show that, although alpha1beta1 integrin does not protect human effector CD4(+) T cells from IL-2-withdrawal-induced apoptosis, it does enhance the pro-survival effect of IL-7, further emphasizing the importance of the alpha1beta1/IL-7R synergistic effect. Together our results identify a new function of alpha1beta1 integrin in T cells and suggest that activation of effector CD4(+) T cells through alpha1beta1 integrin and IL-7R is an important regulatory pathway in T-cell-dependent osteoclastogenesis. Further understanding of the mechanisms by which IL-7R and alpha1beta1 integrin promote T-cell-mediated osteoclastogenesis will lead to new insights into the regulatory pathways of T-cell-dependent bone resorption associated with autoimmune diseases.

L-NAME inhibits tumor cell progression and pulmonary metastasis of r/m HM-SFME-1 cells by decreasing NO from tumor cells and TNF-alpha from macrophages

Highly metastatic ras/myc-transformed serum-free mouse embryo (r/m HM-SFME-1) cells were injected subcutaneously to mice and the effects of Nomega-nitro-L-arginine methyl ester (L-NAME) on the tumor progression and pulmonary metastasis were investigated. In addition, production of nitric oxide (NO), matrix metalloproteinases (MMPs) and tumor necrosis factor-alpha (TNF-alpha) in the tumor cells and in a mouse macrophage-like cell line, J774.1 cells, was analyzed. The increase in footpad thickness was significantly smaller in the mice which were fed the L-NAME containing water (4.24+/-0.39 mg/day/mouse). The number of the tumor cells metastasized to the lungs was smaller in the L-NAME treated mice, although statistical significance was not found. Co-treatment of r/m HM-SFME-1 cells with interferon-gamma (IFN-gamma; 100 U/ml) and lipopolysaccharide (LPS; 0.5 microg/ml) significantly enhanced NO production, and the presence of L-NAME at 1 mM significantly decreased this response. In r/m HM-SFME-1 cells, MMP-2 was undetectable and MMP-9 was also very little in the basal level, and both MMPs were unaffected by the IFN-gamma and/or LPS treatments, not to mention by the L-NAME treatment. In J774.1 cells, any treatment including LPS appeared to enhance MMP-9 production, however, this upregulation was not inhibited by the additional presence of L-NAME. Production of TNF-alpha by J774.1 cells was markedly enhanced with LPS treatment, and this enhancement was significantly reduced in the presence of L-NAME. These results indicate that the inhibitory effects of L-NAME on the tumor cell progression and pulmonary metastasis could be due to suppression of NO from tumor cells and TNF-alpha from macrophages (Mol Cell Biochem, 2007).

Human articular chondrocytes produce IL-7 and respond to IL-7 with increased production of matrix metalloproteinase-13

Introduction

Fibronectin fragments have been found in the articular cartilage and synovial fluid of patients with osteoarthritis and rheumatoid arthritis. These matrix fragments can stimulate production of multiple mediators of matrix destruction, including various cytokines and metalloproteinases. The purpose of this study was to discover novel mediators of cartilage destruction using fibronectin fragments as a stimulus.

Methods

Human articular cartilage was obtained from tissue donors and from osteoarthritic cartilage removed at the time of knee replacement surgery. Enzymatically isolated chondrocytes in serum-free cultures were stimulated overnight with the 110 kDa α5β1 integrin-binding fibronectin fragment or with IL-1, IL-6, or IL-7. Cytokines and matrix metalloproteinases released into the media were detected using antibody arrays and quantified by ELISA. IL-7 receptor expression was evaluated by flow cytometry, immunocytochemical staining, and PCR.

Results

IL-7 was found to be produced by chondrocytes treated with fibronectin fragments. Compared with cells isolated from normal young adult human articular cartilage, increased IL-7 production was noted in cells isolated from older adult tissue donors and from osteoarthritic cartilage. Chondrocyte IL-7 production was also stimulated by combined treatment with the catabolic cytokines IL-1 and IL-6. Chondrocytes were found to express IL-7 receptors and to respond to IL-7 stimulation with increased production of matrix metalloproteinase-13 and with proteoglycan release from cartilage explants.

Conclusion

These novel findings indicate that IL-7 may contribute to cartilage destruction in joint diseases, including osteoarthritis.

Estrogen deficiency, T cells and bone loss

Estrogen plays a fundamental role in the maintenance of skeletal homeostasis. Although estrogen is established to have direct effects on bone cells, animal studies have identified additional regulatory effects of estrogen centered at the level of the adaptive immune response. Furthermore, a potential role for reactive oxygen species has now been identified in both humans and animals. One of the major challenges has been to integrate a multitude of redundant pathways and cytokines, that all appear capable of playing a relevant role, into a global model of postmenopausal osteoporosis. This review presents our current understanding of the process of estrogen deficiency mediated bone destruction and explores some of the most recent findings and hypotheses to explain estrogen action in bone.

Importance of interleukin-7 in the development of experimental graft-versus-host disease

Interleukin (IL)-7 promotes both thymopoiesis and mature T lymphocyte survival and proliferation in experimental murine models of hematopoietic stem cell (HSC) transplantation. Because HSC products for transplantation also may contain IL-7-responsive mature T lymphocytes, we examined whether IL-7 is necessary for the induction of GVHD after allogeneic bone marrow transplantation (BMT). Lethally irradiated C57BL6J (B6) and B6.IL-7(-/-) (both H2K(b)) recipient mice were co-transplanted with T cell-depleted (TCD) bone marrow cells and lymph nodes (LNs) from either congenic B6.SJL (CD45.1(+)) or allogeneic BALB/c (H2K(d)) donor mice. After transplantation, the recipient mice were subcutaneously injected with either human recombinant IL-7 or phosphate-buffered saline (PBS) for 60 days. No evidence of GVHD was detected in the congenic recipients or in the allogeneic B6/IL-7(-/-) recipients treated with PBS; in contrast, significantly increased rates of GVHD-related mortality and morbidity were found in the allogeneic B6.IL-7(-/-) recipients treated with IL-7. The proliferation and number of donor T cells were significantly lower at day 30 post-BMT in the PBS-treated B6.IL-7(-/-) recipients compared with the IL-7-treated B6.IL-7(-/-) mice. These experiments demonstrate that IL-7 is an important factor in the development of GVHD, presumably by supporting the survival, proliferation, and possibly activation of alloreactive donor-derived T cells in the recipients.

Inflammation and ectopic lymphoid structures in rheumatoid arthritis synovial tissues dissected by genomics technology: identification of the interleukin-7 signaling pathway in tissues with lymphoid neogenesis

OBJECTIVE

In approximately 25% of synovial tissues from rheumatoid arthritis (RA) patients, infiltrates of T cells, B cells, and follicular dendritic cells (FDCs) are spatially organized into structures resembling lymph nodes with germinal centers. The remainder of the tissues lack FDCs and show either a diffuse or an aggregated T cell and B cell infiltrate. To gain more insight into this specific disease process, we sought to identify the genes expressed in RA tissues with ectopic lymphoid structures.

METHODS

Gene expression profiling of RA synovial tissues was determined by complementary DNA microarray analysis and quantitative real-time polymerase chain reaction. The presence of lymphoid follicles and localization of interleukin-7 (IL-7) in synovial tissue sections was determined by immunofluorescence staining using specific antibodies.

RESULTS

Findings of gene expression analysis confirmed previous reports that tissues with lymphoid structures showed elevated expression of CXCL13, CCL21, CCR7, and lymphotoxin alpha and beta messenger RNA. In addition, the tissues also showed enhanced expression of the chemokines CXCL12 and CCL19 and the associated receptors CXCR4 and CXCR5, which are important for the attraction of T cells, B cells, and dendritic cells. Pathway analysis revealed increased expression of genes involved in JAK/STAT signaling, T cell- and B cell-specific pathways, Fcepsilon receptor type I signaling in mast cells, and IL-7 signal transduction in the tissues with ectopic lymphoid follicles, accompanied by increased expression of IL-7 receptor alpha (IL-7Ralpha)/IL-2Rgamma chains and IL-7. Protein expression of IL-7 in RA tissues was localized within fibroblast-like synoviocytes, macrophages, and blood vessels and was colocalized with extracellular matrix structures around the B cell follicles.

CONCLUSION

Activation of the IL-7 pathway may play an important role in lymphoid neogenesis, analogous to its role in the development of normal lymphoid tissue.

Ras/myc-transformed serum-free mouse embryo cells under simulated inflammatory and infectious conditions increase levels of nitric oxide and matrix metalloproteinase-9 without a direct association between them

Inflammatory and infectious conditions were simulated in cultures of ras/myc-transformed serum-free mouse embryo (ras/myc SFME) cells, using interferon-gamma (IFN-gamma, 100 units/ml) and lipopolysaccharide (LPS, 0.5 microg/ml) co-treatment for 24 h, to investigate their effects on the expression of inducible nitric oxide synthase (iNOS) mRNA and the production of NO. Aminoguanidine (AG, 1 mM; an NOS inhibitor) along with IFN-gamma and LPS, S-nitroso-N-acetyl-DL-penicillamine (SNAP, 100 microM; an NO donor) and/or (+/-)-N-[(E)-4-Ethyl-2-[(Z)-hydroxyimino]-5-nitro-3-hexene-1-yl]-3-pyridine carboxamide (NOR4, 100 microM; an NO donor), were also added to analyze the possible association of NO with matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1). Co-treatment of cells with IFN-gamma and LPS increased iNOS mRNA expression, NO production, MMP-9 mRNA expression, and 105 kDa MMP-9 production. Additional treatment with the NOS inhibitor AG inhibited NO production, but did not down-regulate the expression of MMP-9 mRNA or 105 kDa MMP-9. The NO donors SNAP and NOR4 did not affect the expression of MMP-9 mRNA, 105 kDa MMP-9 or TIMP-1 mRNA. These results suggest that ras/myc SFME cells respond to infectious and inflammatory conditions and can enhance malignancy as cancer cells due to their increased levels of NO and MMP-9 production, but that NO is not directly associated with MMP-9 in these cells.

Interleukin-7 induced immunopathology in arthritis

Interleukin (IL)-7 is a potent immunoregulatory cytokine that is detected in joints of patients with rheumatoid and juvenile idiopathic arthritis and which correlates with parameters of disease. Several synovial cell types that play an important role in inflammation and immunopathology, such as macrophages, dendritic cells, and fibroblasts, produce IL-7. IL-7 induces cytokines produced by arthritogenic T cells (for example, interferon gamma (IFNgamma), IL-17), T cell differentiating factors (for example, IL-12), chemokines capable of attracting inflammatory cells (for example, macrophage induced gene (MIG), macrophage inflammatory protein (MIP)-1alpha) as well as molecules involved in cell adhesion, migration, and costimulation (for example, lymphocyte function associated antigen (LFA)-1, CD40, CD80). In addition, IL-7 can induce bone loss by stimulating osteoclastogenesis that is dependent on receptor activator of nuclear factor kappaB ligand (RANKL). IL-7 induces tumour necrosis factor alpha (TNFalpha) secretion by T cells and by monocytes after T cell dependent monocyte/macrophage activation. Importantly, induction of both IL-7 and IL-7 induced effects seems to be able to operate independent of TNFalpha. Together this suggests that IL-7 is an important cytokine in several rheumatic conditions, capable of inducing inflammation and immunopathology. Thus it may be an important target for immunotherapy.

Endogenous TNFalpha lowers maximum peak bone mass and inhibits osteoblastic Smad activation through NF-kappaB

Endogenous TNFalpha prevents the attainment of maximum achievable peak bone mass in vivo. In vitro, TNFalpha suppresses BMP-2- and TGFbeta-mediated Smad activation through induction of NF-kappaB. Consistently, pharmacological suppression of NF-kappaB augments osteoblast differentiation and mineralization in vitro.

INTRODUCTION

Osteoporosis is a major health threat. Traditional therapeutic strategies have centered on anti-catabolic drugs that block bone resorption. Recently focus has shifted to anabolic agents that actively rebuild lost bone mass. Future strategies may involve elevating peak bone mass to delay osteoporosis development. Recent in vitro studies show that TNFalpha represses osteoblast differentiation and mineralization; however, the mechanisms are poorly understood and the impact of basal TNFalpha concentrations on the acquisition of peak bone mass in vivo is unknown.

MATERIALS AND METHODS

We examined peak BMD, bone volume, and bone turnover makers in mice deficient in TNFalpha or its receptors. We further examined the effect of TNFalpha on Smad-induced signaling by TGFbeta and BMP-2 in vitro using a Smad responsive reporter. The effect of TNFalpha-induced NF-kappaB signaling on Smad signaling and on in vitro osteoblast mineralization was examined using specific NF-kappaB inhibitors and activators, and effects of TNFalpha-induced NF-kappaB signaling on BMP-2-induced Runx2 mRNA were examined using RT-PCR.

RESULTS

Mice null for TNFalpha or its p55 receptor had significantly increased peak bone mass, resulting exclusively from elevated bone formation. In vitro, TNFalpha potently suppressed Smad signaling induced by TGFbeta and BMP-2, downregulated BMP-2-mediated Runx2 expression, and inhibited mineralization of osteoblasts. These effects were mimicked by overexpression of NF-kappaB and prevented by pharmacological NF-kappaB suppression.

CONCLUSIONS

Our data suggest that TNFalpha and NF-kappaB antagonists may represent novel anabolic agents for the maximization of peak basal bone mass and/or the amelioration of pathological bone loss.

Proinflammatory mediator-induced reversal of CD4+,CD25+ regulatory T cell-mediated suppression in rheumatoid arthritis

OBJECTIVE

We previously demonstrated that CD4+,CD25+ regulatory T (Treg) cells are present in increased numbers in the synovial fluid (SF) of rheumatoid arthritis (RA) patients and display enhanced suppressive activity as compared with their peripheral blood (PB) counterparts. Despite the presence of these immunoregulatory cells in RA, chronic inflammation persists. The purpose of the present study was to investigate whether particular proinflammatory mediators that are associated with RA could abrogate CD4+,CD25+ Treg-mediated suppression.

METHODS

Monocyte phenotype was determined by flow cytometry and cytokine levels by enzyme-linked immunosorbent assay. Magnetically sorted CD4+,CD25- and CD4+,CD25+ T cells derived from the PB and SF obtained from RA patients were stimulated alone or in coculture with anti-CD3 monoclonal antibody (mAb) and autologous antigen-presenting cells, in the absence or presence of anti-CD28 mAb or the proinflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), or IL-7.

RESULTS

Monocytes from the SF of RA patients displayed increased expression of HLA class II molecules, CD80, CD86, and CD40 as compared with PB-derived monocytes, indicating their activated status. Mimicking this increased costimulatory potential, addition of anti-CD28 mAb to cocultures of CD4+,CD25- and CD4+,CD25+ T cells resulted in reduced CD4+,CD25+ Treg-mediated suppression in both PB and SF. Furthermore, IL-7 and, to a limited extent, TNFalpha, both of which are produced by activated monocytes and were detected in SF, abrogated the CD4+,CD25+ Treg-mediated suppression. In contrast, IL-6 did not influence Treg-mediated suppression.

CONCLUSION

Our findings suggest that the interaction of CD4+,CD25+ Treg cells with activated monocytes in the joint might lead to diminished suppressive activity of CD4+,CD25+ Treg cells in vivo, thus contributing to the chronic inflammation in RA.

Diversity of regulatory T cells to control arthritis

During follow-up of the suppressive functions of CD4+ T helper (Th) 2 cells in recent years, the suppressive capacities of newly recognised CD4+ Th cells with more widespread suppressive potential have been extensively investigated. These Th cells, collectively termed regulatory T cells, are characterised by the secretion of specific cytokines, such as interleukin (IL)-10 (Tr1 Th cells), transforming growth factor (TGF)beta (Th3 cells) or the constitutive expression of CD25 (naturally occurring T regulatory cells, nTregs). The balance of these regulatory T cells with pro-inflammatory effector T cells, such as Th1 (interferon (IFN)gamma secreting), Th17 (IL-17 secreting) and CD25- Th cells, has been shown to be of pivotal importance for the development and persistence of autoimmune diseases. The high potential of regulatory T cells (in particular nTregs), to efficiently suppress several arthritic responses both in humans and in animal models of arthritis, make them therapeutic targets of interest in arthritic conditions such as rheumatoid arthritis.

IL-7 in allogeneic transplant: clinical promise and potential pitfalls

Much progress has been made in the field of allogeneic stem cell transplantation. However, one major barrier is the delay in immune recovery that can persist for months post-transplant and results in increased susceptibility to infection and relapse of malignancy. Strategies to improve immune recovery must be balanced with the potential for those therapies to exacerbate graft vs host disease. Interleukin 7 is a member of the gammac cytokine family that is required for T-cell development and maintenance of naïve T-cell populations. In addition, IL-7 plays a major role in the expansion of mature T-cells that occurs during lymphopenia and therapeutic IL-7 can enhance both quantitative and functional immune recovery following T-cell depletion. Thus, this agent holds much promise as an immunorestorative agent and as an adjuvant to vaccines or adoptive immunotherapy. Clinic trials with IL-7 are underway. Murine studies with IL-7 in the allogeneic transplant have demonstrated that the potent immune effects of this agent can also be achieved in this setting. However, these studies have indicated that the potential for IL-7 to worsen GVHD exists and that this effect may abrogate the immune benefits. Thus, careful consideration of how best to incorporate IL-7 into allogeneic trials will be needed if the full potential of this agent is to be realized.

Cells of the synovium in rheumatoid arthritis. Macrophages

The multitude and abundance of macrophage-derived mediators in rheumatoid arthritis and their paracrine/autocrine effects identify macrophages as local and systemic amplifiers of disease. Although uncovering the etiology of rheumatoid arthritis remains the ultimate means to silence the pathogenetic process, efforts in understanding how activated macrophages influence disease have led to optimization strategies to selectively target macrophages by agents tailored to specific features of macrophage activation. This approach has two advantages: (a) striking the cell population that mediates/amplifies most of the irreversible tissue destruction and (b) sparing other cells that have no (or only marginal) effects on joint damage.

IL-7 up-regulates TNF-alpha-dependent osteoclastogenesis in patients affected by solid tumor

Background

Interleukin-7 (IL-7) is a potent regulator of lymphocyte development, which has also significant effects on bone; in fact it is a potent osteoclastogenic factor. Some human solid tumors produce high IL-7 levels, suggesting a potential IL-7 role on tumor development and progression.

Methodology

We studied 50 male patients affected by solid tumors, and their blood samples were collected at tumor diagnosis. PBMCs were isolated and cultured with/without IL-7 to study its influence on osteoclastogenesis. Serum and cell culture supernatant IL-7 levels were measured by ELISA. The quantitative analysis of IL-7 expression on T and B cells was performed by Real-Time PCR.

Principal Findings

Serum IL-7 levels were highest in osteolytic cancer patients, followed by cancer patients without bone lesions, and then healthy controls. We showed the IL-7 production in PBMC cultures and particularly in monocyte and B cell co-cultures. A quantitative analysis of IL-7 expression in T and B cells confirmed that B cells had a high IL-7 expression. In all cell culture conditions, IL-7 significantly increased osteoclastogenesis and an anti-IL-7 antibody inhibited it. We demonstrated that IL-7 supports OC formation by inducing the TNF-α production and low RANKL levels, which synergize in promoting osteoclastogenesis.

Conclusions

We demonstrated the presence of high serum IL-7 levels in patients with bone metastasis, suggesting the use of serum IL-7 level as a clinical marker of disease progression and of bone involvement. Moreover, we showed the capability of IL-7 to stimulate spontaneous osteoclastogenesis of bone metastatic patients and to induce osteoclastogenesis in cancer patients without bone involvement. These findings add further details to the disclosure of the mechanisms controlling bone metastasis in solid tumors.

Persistence of interleukin 7 activity and levels on tumour necrosis factor alpha blockade in patients with rheumatoid arthritis

OBJECTIVES

To identify the mechanism of interleukin (IL)7-stimulated tumour necrosis factor alpha (TNFalpha) production and to determine the relationship between intra-articular IL7 and TNFalpha expression levels in patients with rheumatoid arthritis (RA). In addition, the effect of TNFalpha blockade on IL7 activity and on IL7 levels was studied.

METHODS

The effect of IL7 on isolated CD4 T cells and CD14 monocytes/macrophages was studied. IL7 and TNFalpha levels were measured in the synovial fluid of patients with RA. In RA synovial tissue, IL7 and TNFalpha expression was assessed in addition to IL1beta, numbers of inflammatory cells and adhesion molecule expression. The extent to which TNFalpha blockade could prevent IL7-induced lymphocyte responses was studied in vitro. In addition, regulation of serum IL7 levels on anti-TNFalpha therapy (adalimumab) was studied.

RESULTS

IL7 induced cell contact-dependent TNFalpha production by cocultures of T cells and monocytes, but not by T cells and monocytes cultured separately. IL7 and TNFalpha levels in RA synovial fluid and synovial tissue significantly correlated. IL7-stimulated lymphocyte responses were not inhibited by TNFalpha blockade. Circulating IL7 levels were significantly reduced in patients who successfully responded to anti-TNFalpha treatment. However, IL7 levels persisted in non-responders.

CONCLUSION

The present data suggest that IL7 is an important inducer of T cell-dependent TNFalpha production in RA joints. This may contribute to the correlation of intra-articular IL7 and TNFalpha in these joints. Furthermore, the persistence of IL7-induced inflammatory activity on TNFalpha blockade in vitro and persistence of IL7 levels and disease activity in anti-TNFalpha non-responders suggest that IL7 might additionally promote TNFalpha-independent inflammation.

IFN-gamma stimulates osteoclast formation and bone loss in vivo via antigen-driven T cell activation

T cell-produced cytokines play a pivotal role in the bone loss caused by inflammation, infection, and estrogen deficiency. IFN-gamma is a major product of activated T helper cells that can function as a pro- or antiresorptive cytokine, but the reason why IFN-gamma has variable effects in bone is unknown. Here we show that IFN-gamma blunts osteoclast formation through direct targeting of osteoclast precursors but indirectly stimulates osteoclast formation and promotes bone resorption by stimulating antigen-dependent T cell activation and T cell secretion of the osteoclastogenic factors RANKL and TNF-alpha. Analysis of the in vivo effects of IFN-gamma in 3 mouse models of bone loss - ovariectomy, LPS injection, and inflammation via silencing of TGF-beta signaling in T cells - reveals that the net effect of IFN-gamma in these conditions is that of stimulating bone resorption and bone loss. In summary, IFN-gamma has both direct anti-osteoclastogenic and indirect pro-osteoclastogenic properties in vivo. Under conditions of estrogen deficiency, infection, and inflammation, the net balance of these 2 opposing forces is biased toward bone resorption. Inhibition of IFN-gamma signaling may thus represent a novel strategy to simultaneously reduce inflammation and bone loss in common forms of osteoporosis.

Antagonistic and synergistic effects of glucocorticoids and IL-7 on CD4+ T cell activation

Glucocorticoids (GCs) are steroidal compounds widely used to treat chronic and acute inflammatory diseases. In particular, GCs at pharmacological doses induce apoptosis of activated and naïve T cells, inhibit their proliferation and block pro-inflammatory cytokine secretion. At physiological concentrations, the effect of these steroids on T cell immunity are not yet fully understood, and various studies reported paradoxical roles exerted by GCs on T cell immunity. Here, we show that GCs surprisingly induce proliferation of activated CD4(+) T cells in the presence of IL-7, a cytokine secreted in the thymus and at mucosal sites. Increased proliferation is dependent on a GC-mediated survival of mitotic cells. Moreover, we observe a downmodulation of Th1 cytokine secretion in cells treated with GCs, an outcome which is not affected by the presence of IL-7. GCs exert thus a positive role in the presence of IL-7 by enhancing proliferation of CD4(+) T cells and simultaneously a negative role by suppressing pro-inflammatory cytokine production.

Estrogen deficiency and bone loss: an inflammatory tale

Estrogen plays a fundamental role in skeletal growth and bone homeostasis in both men and women. Although remarkable progress has been made in our understanding of how estrogen deficiency causes bone loss, the mechanisms involved have proven to be complex and multifaceted. Although estrogen is established to have direct effects on bone cells, recent animal studies have identified additional unexpected regulatory effects of estrogen centered at the level of the adaptive immune response. Furthermore, a potential role for reactive oxygen species has now been identified in both humans and animals. One major challenge is the integration of a multitude of redundant pathways and cytokines, each apparently capable of playing a relevant role, into a comprehensive model of postmenopausal osteoporosis. This Review presents our current understanding of the process of estrogen deficiency-mediated bone destruction and explores some recent findings and hypotheses to explain estrogen action in bone. Due to the inherent difficulties associated with human investigation, many of the lessons learned have been in animal models. Consequently, many of these principles await further validation in humans.

Estrogen Regulation of Immune Cell Bone Interactions

Estrogen deficiency is one of the most frequent causes of osteoporosis in women and a possible cause of bone loss and insufficient skeletal development in men. Estrogen deficiency results from menopause but also by a number of conditions, such as stress, excessive physical activity, and low body weight. The mechanism by which estrogen deficiency causes bone loss remains largely unknown. Estrogen deficiency leads to an increase in the immune function, which culminates in an increased production of TNF by activated T cells. TNF increases osteoclast formation and bone resorption both directly and by augmenting the sensitivity of maturing osteoclasts to the essential osteoclastogenic factor RANKL. Increased T cell production of TNF is induced by estrogen deficiency via a complex mechanism mediated by antigen-presenting cells and involving the cytokines IFN-gamma, IL-7, and TGF-beta. Herein we review the experimental evidence that suggests that estrogen prevents bone loss by regulating T cell function and immune cell bone interactions.

The role of T lymphocytes in bone metabolism

Recent findings from animal models suggest that the bone loss induced by estrogen deficiency may stem in large measure from a pathological upregulation of the adaptive immune response. While the role of activated T cells in the osteoporosis driven by inflammatory conditions and infection has been well documented, only recently has the role of T cells in the bone destruction associated with estrogen deficiency begun to be appreciated. In vivo and in vitro models of postmenopausal osteoporosis demonstrate that estrogen deficiency leads to an increase in the adaptive immune function that culminates in an increased production of tumor necrosis factor alpha (TNF) by activated T cells. TNF increases osteoclast (OC) formation and bone resorption both directly and by augmenting the sensitivity of maturing OCs to the essential osteoclastogenic factor receptor activator of nuclear factor kappaB ligand. The activation and expansion of TNF-producing T cells are key steps in estrogen deficiency-driven bone loss and are regulated by multiple interacting cytokines including transforming growth factor-beta, interleukin-7, and interferon-gamma, as well as by the process of antigen presentation. Herein, we review the experimental evidence that suggests estrogen prevents bone loss by regulating T-cell function and immune cell bone interactions.

Rheumatic diseases: the effects of inflammation on bone

Rheumatoid arthritis, juvenile idiopathic arthritis, the seronegative spondyloarthropathies including psoriatic arthritis, and systemic lupus erythematosus are all examples of rheumatic diseases in which inflammation is associated with skeletal pathology. Although some of the mechanisms of skeletal remodeling are shared among these diseases, each disease has a unique impact on articular bone or on the axial or appendicular skeleton. Studies in human disease and in animal models of arthritis have identified the osteoclast as the predominant cell type mediating bone loss in arthritis. Many of the cytokines and growth factors implicated in the inflammatory processes in rheumatic diseases have also been demonstrated to impact osteoclast differentiation and function either directly, by acting on cells of the osteoclast-lineage, or indirectly, by acting on other cell types to modulate expression of the key osteoclastogenic factor receptor activator of nuclear factor (NF) kappaB ligand (RANKL) and/or its inhibitor osteoprotegerin (OPG). Further elucidation of the mechanisms responsible for inflammation-induced bone loss will potentially lead to the identification of novel therapeutic strategies for the prevention of bone loss in these diseases. In this review, we provide an overview of the cell types, inflammatory mediators, and mechanisms that are implicated in bone loss and new bone formation in inflammatory joint diseases.

Increased intraarticular interleukin-7 in rheumatoid arthritis patients stimulates cell contact-dependent activation of CD4(+) T cells and macrophages

OBJECTIVE

To determine the level of intraarticular expression of interleukin-7 (IL-7) in patients with rheumatoid arthritis (RA) and to investigate the mechanisms by which IL-7 facilitates activation of CD4(+) T cells and monocyte/macrophages in RA.

METHODS

IL-7 levels were measured in synovial fluid obtained from patients with RA and patients with osteoarthritis (OA). Immunohistologic analysis was used to assess the expression of IL-7 in synovial tissue from patients with RA. Proliferation and activation markers were determined in order to measure the effect of IL-7 on mononuclear cells, isolated CD4(+) T cells, and monocyte/macrophages from the peripheral blood and synovial fluid. Cocultures of CD4(+) T cells and monocytic cells in the absence or presence of a semipermeable membrane were performed to assess the extent to which IL-7 induces its effects, either contact dependently or via soluble mediators.

RESULTS

IL-7 levels were increased in synovial fluid from patients with RA compared with the levels in synovial fluid from patients with OA. Macrophages, fibroblasts, and endothelial cells in the joint lining tissue expressed abundant IL-7. In vitro, synovial fluid CD4(+) T cells and macrophages were hyperresponsive to IL-7 when compared with peripheral blood cells. Furthermore, IL-7 enhanced cell contact-dependent activation of CD4(+) T cells and monocyte/macrophages.

CONCLUSION

The abundant intraarticular expression of IL-7 and the stimulation by IL-7 of contact-dependent activation of CD4(+) T cells and monocytic cells indicate that this cytokine plays an important proinflammatory role in RA synovitis. Further identification of IL-7-induced pathways may improve understanding of the important interactive role of CD4(+) T cells and monocytic cells in RA.

Role of the immune system in postmenopausal bone loss

Postmenopausal osteoporosis stems from estrogen deficiency. The mechanisms by which estrogen deficiency drives bone destruction are complex and poorly understood. Recent findings from animal models suggest that postmenopausal bone loss may stem in large measure from a pathologic upregulation of the adaptive immune response. While the role of activated T cells in the bone loss driven by inflammatory conditions such as rheumatoid arthritis has been well documented, only recently has the role of T cells in the bone destruction associated with estrogen deficiency begun to be appreciated. In vivo and in vitro models of postmenopausal osteoporosis demonstrate that the activation and expansion of tumor necrosis factor-a producing T cells is a key step in estrogen deficiency driven bone loss and is regulated by multiple interacting cytokines including transforming growth factor-b, interleukin-7, and interferon-g, as well as by the process of antigen presentation. This paper presents recent findings pertaining to this new view of postmenopausal osteoporosis.

Relationship of serum interleukin-7 concentration and the coagulation state in children with nephrotic syndrome

BACKGROUND

Enhanced platelet reactivity may play a significant role in the hypercoagulable state of nephrotic syndrome (NS). Thrombocytosis with platelet aggregation cause the release of some cytokines, among them interleukin-7 (IL-7). The aim of the study was to evaluate serum IL-7 levels in children with the symptoms of NS and to determine a correlation between its concentration and platelet count, other hemostatic factors, and NS intensity.

METHODS

The study was performed in two groups. I--the examined group of 26 children with NS (12 boys, 14 girls) aged 6.8 +/- 2.1 years, subjected to two examinations: A--before treatment, B--during treatment with prednisone (60 mg/kg 24 h after albuminuria regression); and II--the control group (C) of 20 healthy children. Serum IL-7 level was assayed by enzyme-linked immunosorbent assay method using a R & D Quantikine set.

RESULTS

In group I, IL-7 level in examination A (33.33 +/- 33.24 pg/mL) was higher than in the control subjects (P < 0.01). In examination B, IL-7 concentration was reduced to the level of 10.86 +/- 5.22 pg/mL and did not differ from the controls (P > 0.05). A positive correlation was observed between IL-7 and platelet count and serum fibrinogen level. A negative correlation was noted with antithrombin III concentration. No correlation was found with serum levels of albumin and cholesterol or urine protein.

CONCLUSION

In children with NS, serum IL-7 level increases proportionally to the elevated platelet count and other hemostatic components, but shows no correlation with serum albumin or urine protein.

Protein microarray analysis of disease activity in pediatric inflammatory bowel disease demonstrates elevated serum PLGF, IL-7, TGF-beta1, and IL-12p40 levels in Crohn's disease and ulcerative colitis patients in remission versus active disease

OBJECTIVES

Cytokines and growth factors play a major role in the dysregulated immune response in inflammatory bowel disease (IBD). We hypothesized that significant differences exist between the serum cytokine and growth factor profiles of pediatric IBD patients with active disease (AD) and those in remission, and that levels of some of these soluble mediators may be used to define regulators in IBD and determine disease activity.

METHODS

Eighty-eight consecutive patients with confirmed Crohn's disease (CD) and ulcerative colitis (UC) seen at the Duke Children's Hospital were prospectively enrolled and a serum sample was obtained. Data were recorded at the time of serum collection to calculate disease activity indices. The relative expression of 78 cytokines, growth factors, and soluble receptors was determined using proprietary antibody-based protein microarrays amplified by rolling circle amplification. SPSS 8 (SPSS Inc., Chicago, IL) was used to compare protein profiles for CD and UC patients in clinical remission (CR) versus AD.

RESULTS

Sixty-five CD patients and 23 UC patients were enrolled. Forty-one CD patients had available samples and PCDAI results. Twenty-two patients were in remission PCDAI < or = 12.5 (median 5), 19 patients had disease activity >15 (median 30). Univariate analysis revealed that PLGF, IL-7, IL-12p40, and TGF-beta1 cytokine levels were significantly elevated for patients in CR versus AD (p < 0.01). Twelve UC serum samples had Seo/Truelove Witt AI for analysis. Five patients were in remission by TW AI and Seo AI < or =110 and 7 patients had active mild-to-severe disease by TW and Seo AI >110. Only one cytokine, IL12p40, showed significance between CR versus AD (p < 0.02).

CONCLUSIONS

Surprisingly, we found no differences in circulating levels of proinflammatory cytokines but found that pediatric IBD patients in remission compared to those with AD had higher levels of specific circulating cytokines, including the regulatory cytokines IL-12p40 and TGF-beta1. It may be that these cytokines directly regulate intestinal inflammation in IBD or reflect the activity of T regulatory cells in negatively regulating the inflammatory response. Further studies will be needed to validate our results to define the molecular pathways involved in the intestinal immune response in man.

Protein microarray analysis of disease activity in pediatric inflammatory bowel disease demonstrates elevated serum PLGF, IL-7, TGF-beta1, and IL-12p40 levels in Crohn's disease and ulcerative colitis patients in remission versus active disease

OBJECTIVES

Cytokines and growth factors play a major role in the dysregulated immune response in inflammatory bowel disease (IBD). We hypothesized that significant differences exist between the serum cytokine and growth factor profiles of pediatric IBD patients with active disease (AD) and those in remission, and that levels of some of these soluble mediators may be used to define regulators in IBD and determine disease activity.

METHODS

Eighty-eight consecutive patients with confirmed Crohn's disease (CD) and ulcerative colitis (UC) seen at the Duke Children's Hospital were prospectively enrolled and a serum sample was obtained. Data were recorded at the time of serum collection to calculate disease activity indices. The relative expression of 78 cytokines, growth factors, and soluble receptors was determined using proprietary antibody-based protein microarrays amplified by rolling circle amplification. SPSS 8 (SPSS Inc., Chicago, IL) was used to compare protein profiles for CD and UC patients in clinical remission (CR) versus AD.

RESULTS

Sixty-five CD patients and 23 UC patients were enrolled. Forty-one CD patients had available samples and PCDAI results. Twenty-two patients were in remission PCDAI < or = 12.5 (median 5), 19 patients had disease activity >15 (median 30). Univariate analysis revealed that PLGF, IL-7, IL-12p40, and TGF-beta1 cytokine levels were significantly elevated for patients in CR versus AD (p < 0.01). Twelve UC serum samples had Seo/Truelove Witt AI for analysis. Five patients were in remission by TW AI and Seo AI < or =110 and 7 patients had active mild-to-severe disease by TW and Seo AI >110. Only one cytokine, IL12p40, showed significance between CR versus AD (p < 0.02).

CONCLUSIONS

Surprisingly, we found no differences in circulating levels of proinflammatory cytokines but found that pediatric IBD patients in remission compared to those with AD had higher levels of specific circulating cytokines, including the regulatory cytokines IL-12p40 and TGF-beta1. It may be that these cytokines directly regulate intestinal inflammation in IBD or reflect the activity of T regulatory cells in negatively regulating the inflammatory response. Further studies will be needed to validate our results to define the molecular pathways involved in the intestinal immune response in man.

Interleukin-7 deficiency in rheumatoid arthritis: consequences for therapy-induced lymphopenia

We previously demonstrated prolonged, profound CD4⁺ T-lymphopenia in rheumatoid arthritis (RA) patients following lymphocyte-depleting therapy. Poor reconstitution could result either from reduced de novo T-cell production through the thymus or from poor peripheral expansion of residual T-cells. Interleukin-7 (IL-7) is known to stimulate the thymus to produce new T-cells and to allow circulating mature T-cells to expand, thereby playing a critical role in T-cell homeostasis. In the present study we demonstrated reduced levels of circulating IL-7 in a cross-section of RA patients. IL-7 production by bone marrow stromal cell cultures was also compromised in RA. To investigate whether such an IL-7 deficiency could account for the prolonged lymphopenia observed in RA following therapeutic lymphodepletion, we compared RA patients and patients with solid cancers treated with high-dose chemotherapy and autologous progenitor cell rescue. Chemotherapy rendered all patients similarly lymphopenic, but this was sustained in RA patients at 12 months, as compared with the reconstitution that occurred in cancer patients by 3–4 months. Both cohorts produced naïve T-cells containing T-cell receptor excision circles. The main distinguishing feature between the groups was a failure to expand peripheral T-cells in RA, particularly memory cells during the first 3 months after treatment. Most importantly, there was no increase in serum IL-7 levels in RA, as compared with a fourfold rise in non-RA control individuals at the time of lymphopenia. Our data therefore suggest that RA patients are relatively IL-7 deficient and that this deficiency is likely to be an important contributing factor to poor early T-cell reconstitution in RA following therapeutic lymphodepletion. Furthermore, in RA patients with stable, well controlled disease, IL-7 levels were positively correlated with the T-cell receptor excision circle content of CD4⁺ T-cells, demonstrating a direct effect of IL-7 on thymic activity in this cohort.

An update on the cytokine network in rheumatoid arthritis

PURPOSE OF REVIEW

To update the knowledge accumulated on the contribution of cytokines to rheumatoid arthritis and related animal models. Publications from the end of 2002 and 2003 period were analyzed for a selection.

RECENT FINDINGS

A better understanding of the clinical results with tumor necrosis factor-alpha inhibitors has come from studies in treated patients. The expected effect of infliximab on the apoptosis of cells expressing tumor necrosis factor-alpha was not observed in synovium biopsy specimens. The mode of action of tumor necrosis factor-alpha on bone destruction has been clarified in gene-defective mice. Tumor necrosis factor-alpha acts through osteoclasts--an effect that is inhibited with osteoprotegerin. New interleukin-1 inhibitors with a potential for increased efficacy, such as interleukin-1trap, have been manufactured and are now being tested in rheumatoid arthritis. The list of cytokines of interest for therapeutic intervention has been growing rapidly. The results with animal models have provided clues to control arthritis with natural interleukin-18 inhibitors, such as interleukin-18 BP. Additional results have been accumulated that indicate the contribution of T cell subsets in inflammation and destruction through the production of interleukin-17. Synergistic interactions with other cytokines are critical in the interleukin-17 tuning effects. Macrophage inhibitory factor was described many years ago. Its comeback is based on properties of synoviocyte activation and proliferation.

SUMMARY

Such findings are critical for a better understanding of response heterogeneity in patients treated with the cytokine inhibitors now on the market. New therapeutic approaches are been planned from these results.

Cytokines in the rheumatic diseases

Extensive data has accumulated over the last 10 to 15 years to implicate various cytokines in pathways of pathophysiology in rheumatic diseases. Abnormalities in cytokine production are not the cause of these diseases, but reflect continual production by immune and inflammatory cells. Cytokines are heterogeneous and function in an overlapping and redundant network. An important principle to emerge is that the net biologic response in a diseased organ or tissue reflects a balance between the local levels of proinflammatory and anti-inflammatory cytokines and factors. Thus, a chronic disease may result from the excess production of proinflammatory cytokines or the inadequate production of anti-inflammatory cytokines. This article summarizes the role of cytokines in rheumatic diseases by focusing on each disease and the involved pathways of pathophysiology.

Differentiation of naive CD4+ T cells towards T helper 2 cells is not impaired in rheumatoid arthritis patients

An impaired differentiation of naive CD4+ T cells towards Th2 cells may contribute to the chronic tissue-destructive T-cell activity in rheumatoid arthritis (RA). The differentiation of naive CD4+ T cells into memory Th2 cells by IL-7 in comparison with that by IL-4 was studied in RA patients and in healthy controls. Naive CD4+ T cells from peripheral blood were differentiated by CD3/CD28 costimulation in the absence of or in the presence of IL-7 and/or IL-4. The production of IFN-gamma and IL-4 was measured by ELISA and by single-cell FACS analysis to indicate Th1 and Th2 cell activity. CD3/CD28 costimulation and IL-7 were early inducers of IL-4 production, but primarily stimulated IFN-gamma production. In contrast, in short-term cultures exogenously added IL-4 did not prime for IL-4 production but suppressed IL-7-induced IFN-gamma production. Upon long-term stimulation of naive CD4+ T cells, IFN-gamma production was differentially regulated by IL-7 and IL-4, but IL-4 production was increased by both IL-7 and IL-4. IL-7 and IL-4 additively induced polarization towards a Th2 phenotype. This susceptibility of naive CD4+ T cells to become Th2 cells upon culture with IL-7 and IL-4 was increased in RA patients compared with that in healthy controls. These findings demonstrate that, in RA patients, differentiation of naive CD4+ T cells towards a Th2 phenotype by CD3/CD28 costimulation, IL-7 and IL-4 is not impaired. The perpetuation of arthritogenic T-cell activity in RA therefore seems not to be the result of intrinsic defects of naive CD4+ T cells to develop towards suppressive memory Th2 cells.