Abnormal IL-2 receptor levels in non-pregnant women with a history of recurrent miscarriage

BACKGROUND

Immunological abnormalities have been found in pregnant women with a history of recurrent miscarriage. This study compared interleukin-2 receptor (IL-2R) levels in non-pregnant women with a history of recurrent miscarriage with those found in serum from a non-pregnant group with no such history.

METHODS

Group 1 comprised 49 non-pregnant women with a history of recurrent miscarriage (at least three consecutive miscarriages). Group 2 comprised 22 non-pregnant women with no history of miscarriage. Serum IL-2R levels were measured in all patients.

RESULTS

The results obtained showed that although all women were not pregnant at the time of sampling, IL-2R levels were significantly higher in women in Group 1 compared with those in Group 2 (1589 +/- 1289 versus 1082 +/- 823 pg/ml; P < 0.05). Follow-up data were available for 21 women from Group 1. The next pregnancy ended successfully for 14 of these women, while seven miscarried again. The IL-2R levels obtained pre-pregnancy were not significantly different between the two groups (1480 +/- 910 versus 1356 +/- 716 pg/ml).

CONCLUSION

This study has shown that non-pregnant women with a history of recurrent miscarriage have raised IL-2R levels. These increased pre-pregnancy IL-2R levels did not necessarily predict miscarriage for the next pregnancy.

A novel anti-inflammatory role for simvastatin in inflammatory arthritis

3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins) exert favorable effects on lipoprotein metabolism, but may also possess anti-inflammatory properties. Therefore, we explored the activities of simvastatin, a lipophilic statin, in a Th1-driven model of murine inflammatory arthritis. We report in this study that simvastatin markedly inhibited not only developing but also clinically evident collagen-induced arthritis in doses that were unable to significantly alter cholesterol concentrations in vivo. Ex vivo analysis demonstrated significant suppression of collagen-specific Th1 humoral and cellular immune responses. Moreover, simvastatin reduced anti-CD3/anti-CD28 proliferation and IFN-gamma release from mononuclear cells derived from peripheral blood and synovial fluid. Proinflammatory cytokine production in vitro by T cell contact-activated macrophages was suppressed by simvastatin, suggesting that such observations have direct clinical relevance. These data clearly illustrate the therapeutic potential of statin-sensitive pathways in inflammatory arthritis.

Interleukin-18

Interleukin-18 (IL-18), a recently described member of the IL-1 cytokine superfamily, is now recognized as an important regulator of innate and acquired immune responses. IL-18 is expressed at sites of chronic inflammation, in autoimmune diseases, in a variety of cancers, and in the context of numerous infectious diseases. This short review will describe the basic biology of IL-18 and thereafter address its potential effector and regulatory role in several human disease states including autoimmunity and infection. IL-18, previously known as interferon-gamma (IFN-gamma)-inducing factor, was identified as an endotoxin-induced serum factor that stimulated IFN-gamma production by murine splenocytes [(1) ]. IL-18 was cloned from a murine liver cell cDNA library generated from animals primed with heat-killed Propionibacterium acnes and subsequently challenged with lipopolysaccharide [(2) ]. Nucleotide sequencing of murine IL-18 predicted a precursor polypeptide of 192 amino acids lacking a conventional signal peptide and a mature protein of 157 amino acids. Subsequent cloning of human IL-18 cDNA revealed 65% homology with murine IL-18 [(3) ] and showed that both contain an unusual leader sequence consisting of 35 amino acids at their N terminus.

Chemoattraction of human T cells by IL-18

Cell locomotion is crucial to the induction of an effective immune response. We report here the chemoattraction of CD4(+) T cells by IL-18, a member of the IL-1 cytokine family. Recombinant IL-18 increased the proportion of T cells in polarized morphology in vitro and stimulated their subsequent invasion into collagen gels in an IL-18 concentration gradient-dependent manner. Immunofluorescent microscopy studies determined that the major cell type responding to IL-18 was IL-18R(+)CD4(+). Importantly, synovial CD4(+) T cells from patients with rheumatoid arthritis responded to IL-18, adopting polarized morphology and gel invasion without further activation ex vivo, indicating the physiologic relevance of our observations. Finally, injection of rIL-18 into the footpad of DBA/1 mice led to local accumulation of inflammatory cells. These data therefore demonstrate for the first time lymphocyte chemoattractant properties of a member of the IL-1 cytokine family and its relevance in inflammatory diseases.

A novel dendritic cell-induced model of erosive inflammatory arthritis: distinct roles for dendritic cells in T cell activation and induction of local inflammation

Transferring collagen-pulsed, bone marrow-derived dendritic cells (DCs) into congenic DBA/1 recipient mice produced arthritis in joints adjacent to the site of DC transfer and could be inhibited by treatment with TNF antagonists. Disease was Ag specific, as transfer of control, unpulsed DCs, or DCs pulsed with OVA did not produce arthritis. In contrast to other experimental arthritis models, DC-induced arthritis localized to the site of injection and did not spontaneously generalize to uninvolved joints, despite the demonstration of circulating collagen-reactive T cells. Similarly, transfer of T cells primed by collagen/DCs was not sufficient to produce arthritis in recipient mice. In collagen/DC-primed mice however, disease could be induced in uninvolved joints by local administration of noncollagen-pulsed DCs and this could be reduced through TNF inhibition. Similarly, injection of collagen/DC-primed mice with low-dose TNF also resulted in local induction of arthritis, as did administration of TNF to mice receiving T cells from collagen/DC but not OVA/DC-primed mice. Thus, we have demonstrated for the first time that administration of collagen-pulsed mature DCs is sufficient for the induction of arthritis. Furthermore, this disease process is mediated through both adaptive and innate effects of DCs; first, priming of autoreactive T cells and, second, induction of local inflammation via mediators such as TNF.

Role of interleukin 15 and interleukin 18 in inflammatory response

Interleukin 15 (IL15) and interleukin 18 (IL18) are cytokines produced principally by macrophages during innate immune response and subsequently profoundly influence adaptive immunity. Recent studies have shown that IL15 and IL18 play an influential part in inflammatory response. Here we present recent data mainly from our own laboratories illustrating the importance of IL15 and IL18 in the induction and perpetuation of chronic inflammation during experimental and clinical rheumatoid synovitis.

Ultrasound guided versus conventional joint and soft tissue fluid aspiration in rheumatology practice: a pilot study

OBJECTIVE

To compare joint and soft tissue aspiration using a conventional technique with an ultrasound (US) guided technique.

METHODS

In the conventional group, 32 joints in 30 consecutive patients referred for joint aspiration and injection to an experienced consultant rheumatologist were aspirated. In the US guided group, 31 consecutive patients were examined by US to confirm the presence and location of fluid. Following US examination, aspiration was performed by a second rheumatologist based on the US localization of fluid or under direct US guidance.

RESULTS

In the conventional group, successful aspiration was achieved in 10 (32%) joints. In the US guided group, successful aspiration was achieved in 31 (97%) joints. The mean volume of fluid obtained from successful aspirations was similar in both groups (11.7 ml in the US group and 14 ml in the conventional group).

CONCLUSION

The use of US to localize joint and soft tissue fluid collection greatly improves the rate of diagnostic synovial fluid aspiration, particularly in small joints. This has important implications for accurate administration of local steroid therapy and emphasizes the importance of US as a useful tool in clinical rheumatological practice.

Human platelets stimulate mesangial cells to produce monocyte chemoattractant protein-1 via the CD40/CD40 ligand pathway and may amplify glomerular injury

Platelets are thought to play an important role in the initiation and the progression of a variety of glomerulonephritides. This study examined whether platelets induce production of monocyte chemoattractant protein-1 (MCP-1), a chemokine involved in leukocyte recruitment and glomerular injury, by cultured human mesangial cells (MC). To this end, platelets isolated from normal human donors were cocultured with MC at various ratios. MCP-1 synthesis was evaluated by quantitative real-time PCR and enzyme-linked immunosorbent assay. Platelets at 1:100 ratio (MC to platelets) induced an approximately 20-fold increase in mesangial MCP-1 mRNA and protein expression through an obligatory cell-to-cell contact-dependent mechanism. Importantly, blockade of the CD40/CD40 ligand (CD40L) pathway with neutralizing antibodies decreased MCP-1 production by approximately 60%. It was confirmed that CD40 was functionally expressed on MC. Gel-shift assays and inhibitors of phosphorylation were used to demonstrate that activation of p38 mitogen-activated protein kinase, protein tyrosine kinases, and nuclear factor-kappa B activation were essential for MCP-1 production. These data indicate that platelet/MC contact stimulates the production of MCP-1 and may contribute to glomerular inflammatory responses by recruiting leukocytes from the peripheral blood.

Ultrasonography of entheseal insertions in the lower limb in spondyloarthropathy

OBJECTIVE

To compare ultrasonography (US) with clinical examination in the detection of entheseal abnormality of the lower limb in patients with spondyloarthropathy (SpA).

METHODS

35 patients with SpA (ankylosing spondylitis 27; psoriatic arthritis 7; reactive arthritis 1) underwent independent clinical and ultrasonographic examination of both lower limbs at five entheseal sites-superior pole and inferior pole of patella, tibial tuberosity, Achilles tendon, and plantar aponeurosis. US was performed using an ATL (Advanced Technology Laboratories, Bothell, Washington, USA) high definition imaging 3000 machine with linear 7-4 MHz and compact linear 10-5 MHz probes to detect bursitis, structure thickness, bony erosion, and enthesophyte (bony spur). An enthesitis score was formulated from these US findings giving a possible maximum total score of 36.

RESULTS

On clinical examination 75/348 (22%) entheseal sites were abnormal and on US examination 195/348 (56%) sites were abnormal. In 19 entheseal sites with bursitis on US, only five were detected by clinical examination. Compared with US, clinical examination had a low sensitivity (22.6%) and moderate specificity (79.7%) for the detection of enthesitis of the lower limbs. There was no significant correlation between the US score of enthesitis and acute phase parameters such as erythrocyte sedimentation rate (ESR) or C reactive protein (CRP). The intraobserver kappa value for analysis of all sites was 0.9.

CONCLUSIONS

Most entheseal abnormality in SpA is not detected at clinical examination. US is better than clinical examination in the detection of entheseal abnormality of the lower limbs in SpA. A quantitative US score of lower limb enthesitis is proposed but further studies are required to validate it in SpA.

The role of innate mediators in inflammatory response

Cytokines produced by innate immune response can profoundly influence the subsequent adaptive immunity. IL-15 and -18 are two of several mediators produced by macrophages that perform such a function. Here we present recent data mainly from our own laboratory illustrating the important role of IL-15 and -18 in the induction and perpetuation of chronic inflammation during experimental and clinical rheumatoid synovitis.

Novel pathways that regulate tumor necrosis factor-alpha production in rheumatoid arthritis

Clinical intervention studies have clearly shown the benefit in suppressing tumor necrosis factor-alpha (TNF-alpha) rheumatoid arthritis (RA). In consequence, considerable interest has arisen in those pathways that in turn regulate TNF-alpha production, because they may offer further possible therapeutic targets. Several candidate pathways are currently being investigated. They include T cell/macrophage interactions mediated primarily through cell-cell membrane contact; novel cytokine activities; microbial-derived products, in particular bacterial deoxyribonucleic acid sequences; autoreactive T cells, and immunoglobulins. At the subcellular level, there is further interest in targeting signaling and mRNA processing and cytokine cleavage pathways required for optimal TNF-alpha production. The key recent observations in these areas, particularly in the extracellular compartment, are reviewed.

Enhanced Th1 response to Staphylococcus aureus infection in human lactoferrin-transgenic mice

Lactoferrin (Lf) is an iron-binding protein of external secretions and neutrophil secondary granules with antimicrobial and immunomodulatory activities. To further define these properties of Lf, we have investigated the response to Staphylococcus aureus infection in transgenic mice carrying a functional human Lf gene. The transgenic mice cleared bacteria significantly better than congenic littermates, associated with a trend to reduced incidence of arthritis, septicemia, and mortality. We identified two pathways by which S. aureus clearance was enhanced. First, human Lf directly inhibited the growth of S. aureus LS-1 in vitro. Second, S. aureus-infected transgenic mice exhibited enhanced Th1 immune polarization. Thus, spleen cells from infected transgenic mice produced higher levels of TNF-alpha and IFN-gamma and less IL-5 and IL-10 upon stimulation ex vivo with the exotoxin toxic shock syndrome toxin-1 compared with congenic controls. To confirm that these effects of Lf transgene expression could occur in the absence of live bacterial infection, we also showed that Lf-transgenic DBA/1 mice exhibited enhanced severity of collagen-induced arthritis, an established model of Th1-induced articular inflammation. Higher levels of stainable iron in the spleens of transgenic mice correlated with human Lf distribution, but all other parameters of iron metabolism did not differ between transgenic mice and wild-type littermates. These results demonstrate that human Lf can mediate both antimicrobial and immunomodulatory activities with downstream effects on the outcome of immune pathology in infectious and inflammatory disease.

A proinflammatory role of IL-18 in the development of spontaneous autoimmune disease

Serum from patients with systemic lupus erythematosus (SLE) contained significantly higher concentrations of IL-18 than normal individuals. MRL/lpr mice, which develop spontaneous lupus-like autoimmune disease, also had higher serum levels of IL-18 than wild-type MRL/++ mice. Daily injections of IL-18 or IL-18 plus IL-12 resulted in accelerated proteinuria, glomerulonephritis, vasculitis, and raised levels of proinflammatory cytokines in MRL/lpr mice. IL-18-treated MRL/lpr mice also developed a "butterfly" facial rash resembling clinical SLE. In contrast, MRL/lpr mice treated with IL-18 plus IL-12 did not develop a facial rash. The facial lesion in the IL-18-treated mice showed epidermal thickening with intense chronic inflammation accompanied by increased apoptosis, Ig deposition, and early systemic Th2 response compared with control or IL-12 plus IL-18-treated mice. These data therefore show that IL-18 is an important mediator of lupus-like disease and may thus be a novel target for therapeutic intervention of spontaneous autoimmune diseases.

IL-10 improves skin disease and modulates endothelial activation and leukocyte effector function in patients with psoriatic arthritis

Psoriatic arthritis (PsA) provides an ideal disease model in which to investigate the bioactivities of potentially therapeutic cytokines at multiple sites of tissue inflammation. We investigated the effects of IL-10, an antiinflammatory cytokine, given s.c. for 28 days in a double-blind, placebo-controlled study in PsA patients. Synovial/skin biopsies, peripheral blood leukocytes, articular magnetic resonance images, and clinical disease activity scores were obtained sequentially. Modest, but significant clinical improvement in skin, but not articular disease activity scores with only minor adverse effects was observed. Type 1, but not type 2 T cell cytokine production in vitro was suppressed in human rIL-10 compared with placebo recipients. Similarly, monokine production in vitro was reduced, whereas serum soluble TNFRII levels were elevated, indicating suppression of monocyte function. Decreased T cell and macrophage infiltration in synovial tissues was accompanied by reduced P-selectin expression. Moreover, suppressed synovial enhancement on magnetic resonance imaging and reduced alpha(v)beta(3) integrin expression on von Willebrand factor(+) vessels were observed. Together these data demonstrate that a short course of IL-10 modulates immune responses in vivo via diverse effects on endothelial activation, and leukocyte recruitment and effector function. Such biological changes may result in clinically meaningful improvement in disease activity.

A role for IL-18 in neutrophil activation

IL-18 expression and functional activity has been identified in several autoimmune and infectious diseases. To clarify the potential role of IL-18 during early innate immune responses, we have explored the capacity of IL-18 to activate neutrophils. Human peripheral blood-derived neutrophils constitutively expressed IL-18R (alpha and beta) commensurate with the capacity to rapidly respond to IL-18. IL-18 induced cytokine and chemokine release from neutrophils that was protein synthesis dependent, up-regulated CD11b expression, induced granule release, and enhanced the respiratory burst following exposure to fMLP, but had no effect upon the rate of neutrophil apoptosis. The capacity to release cytokine and chemokine was significantly enhanced in neutrophils derived from rheumatoid arthritis synovial fluid, indicating differential responsiveness to IL-18 dependent upon prior neutrophil activation in vivo. Finally, IL-18 administration promoted neutrophil accumulation in vivo, whereas IL-18 neutralization suppressed the severity of footpad inflammation following carrageenan injection. The latter was accompanied by reduction in tissue myeloperoxidase expression and suppressed local TNF-alpha production. Together, these data define a novel role for IL-18 in activating neutrophils and thereby promoting early innate immune responses.

The Sushi domain of soluble IL-15 receptor alpha is essential for binding IL-15 and inhibiting inflammatory and allogenic responses in vitro and in vivo

IL-15 is a pleiotropic cytokine that plays important roles in both innate and adaptive immunity. It is associated with a range of immunopathology, including rheumatoid arthritis and allograft rejection. IL-15 functions through the trimeric IL-15R complex, which consists of a high affinity binding alpha-chain and the common IL-2R beta- and gamma-chains. Characterization of IL-15/IL-15R interactions may facilitate the development of improved IL-15 antagonists for therapeutic interventions. We previously constructed soluble murine IL-15Ralpha (sIL-15Ralpha) by deleting the cytoplasmic and transmembrane domains. To localize the functional domain of IL-15Ralpha, we have now constructed various truncated versions of sIL-15Ralpha. The shortest region retaining IL-15 binding activity is a 65-aa sequence spanning the Sushi domain of IL-15Ralpha. Sushi domains, common motifs in protein-protein interactions, contain four cysteines forming two disulfide bonds in a 1-3 and 2-4 pattern. Amino acid substitution of the first or fourth cysteine in sIL-15Ralpha completely abolished its IL-15 binding activity. This also abrogated the ability of sIL-15Ralpha to neutralize IL-15-induced proinflammatory cytokine production and anti-apoptotic response in vitro. Furthermore, the mutant sIL-15Ralpha lost its ability to inhibit carrageenan-induced local inflammation and allogenic cell-induced T cell proliferation and cytokine production in vivo. Thus, the Sushi domain is critical for the functional activity of sIL-15Ralpha.

Comparative study of intramuscular gold and methotrexate in a rheumatoid arthritis population from a socially deprived area

OBJECTIVE

To compare the risk-benefit ratio of intramuscular gold (gold sodium thiomalate (GST)) and methotrexate (MTX) in a population with rheumatoid arthritis (RA) from a deprived area.

METHODS

Patients with active RA were randomly assigned to open treatment with GST or MTX. Clinical and laboratory assessment was performed at 0, 12, 24, and 48 weeks. Results were analysed on an intention to treat basis.

RESULTS

141 patients were recruited-72 were randomly allocated to GST and 69 to MTX. There were no statistically significant differences found in either the clinical or demographic variables at baseline. At 48 weeks 31 (43%) patients continued to receive GST and 43 (62%) MTX. The median MTX dose achieved was 10 mg. Gold caused significantly more withdrawals for toxicity (43% GST v 19% MTX, p=0.0026, log rank test). Both groups experienced a significant improvement in erythrocyte sedimentation rate, C reactive protein, Ritchie Articular Index, and pain score by 24 weeks (p<0.001, Friedman test). Although a trend towards an improved Health Assessment Questionnaire (HAQ) score and global wellbeing was seen in both groups, this did not reach statistical significance. No differences in efficacy were found when the two groups were compared (Mann-Whitney).

CONCLUSION

GST and low dose MTX showed equivalent efficacy, but toxicity was more common in patients treated with GST. GST, although more toxic, remains a useful alternative for patients in whom MTX is contraindicated.