Terminal differentiation of spontaneous rheumatoid factor-secreting B cells from rheumatoid arthritis patients depends on endogenous interleukin-10

Association of interleukin-10 gene single nucleotide polymorphisms with rheumatoid arthritis in a Chinese population

PURPOSE OF THE STUDY

Increasing numbers of studies show that interleukin (IL)-10 plays a key role in the pathogenesis of autoimmune diseases including rheumatoid arthritis (RA) and acts as an immunomodulatory cytokine. The purpose of the present study was to analyse the relationship between gene single nucleotide polymorphisms (SNPs) in the IL-10 gene and RA susceptibility.

STUDY DESIGN

We genotyped three SNPs (rs1800890, rs3024495, rs3024505) of the IL-10 gene in a Chinese population of 354 RA patients and 367 controls. Genotyping was conducted using TaqMan SNP genotyping assays. Plasma IL-10 levels were measured by ELISA.

RESULTS

The A allele of the rs1800890 variant was significantly related to decreased risk for RA compared with the T allele (A vs T: OR 0.580, 95% CI 0.345 to 0.975, P=0.038). No significant association between the genotype distribution of these SNPs and RA susceptibility was detected. The genotype effect of the dominant model was also evaluated, but no statistical difference was found. Further analysis in RA patients demonstrated that none of these SNPs were associated with rheumatoid factor (RF) or anti-citrullinated protein antibody (anti-CCP). In addition, no significant differences in plasma IL-10 levels were observed among RA patients with different genotypes.

CONCLUSIONS

The IL-10 rs1800890 variant might contribute to RA susceptibility in the Chinese population. Replication studies in different ethnic groups are required to further examine the critical role of IL-10 gene variation in the pathogenesis of RA.

The Mechanisms Underlying Chronic Inflammation in Rheumatoid Arthritis from the Perspective of the Epigenetic Landscape

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that is characterized by synovial hyperplasia and progressive joint destruction. The activation of RA synovial fibroblasts (SFs), also called fibroblast-like synoviocytes (FLS), contributes significantly to perpetuation of the disease. Genetic and environmental factors have been reported to be involved in the etiology of RA but are insufficient to explain it. In recent years, accumulating results have shown the potential role of epigenetic mechanisms, including histone modifications, DNA methylation, and microRNAs, in the development of RA. Epigenetic mechanisms regulate chromatin state and gene transcription without any change in DNA sequence, resulting in the alteration of phenotypes in several cell types, especially RASFs. Epigenetic changes possibly provide RASFs with an activated phenotype. In this paper, we review the roles of epigenetic mechanisms relevant for the progression of RA.

Aging-dependent decline of IL-10 producing B cells coincides with production of antinuclear antibodies but not rheumatoid factors

Aging is associated with development of autoimmunity. Loss of B cell tolerance in the elderly is suggested by an increased prevalence of anti-nuclear antibodies (ANAs) and rheumatoid factors (RFs). Accumulating evidence indicates that B cells also impact autoimmunity via secretion of cytokines. So far, few studies have directly assessed the effect of aging on the latter B cell function. Here, we determined if and how human aging influences the production of cytokines by B cells. In a cross-sectional study, we found that absolute numbers of circulating B cells were similar in 31 young (ages 19-39) and 73 old (age ≥ 60) individuals. Numbers of transitional B cells (CD19(+)CD27(-)CD38(High)CD24(High)) were decreased in old individuals, whereas numbers of naive and memory B cell subsets were comparable in young and old individuals. Short-term in vitro stimulation of whole blood samples revealed that numbers of B cells capable of producing TNF-α were similar in young and old individuals. In contrast, B cells capable of IL-10 production were decreased in old subjects. This decline of IL-10(+) B cells was observed in old individuals that were ANA positive, and in those that were negative for both ANAs and RFs. However, IL-10(+) B cells were remarkably well retained in the circulation of old subjects that were RF positive. Thus, pro-inflammatory TNF-α(+) B cells are retained in the elderly, whereas IL-10(+) B cells generally decline. In addition, our findings indicate that IL-10(+) B cells may differentially impact the development of ANAs and RFs in the elderly.

Putative IL-10 Low Producer Genotypes Are Associated with a Favourable Etanercept Response in Patients with Rheumatoid Arthritis

Outcome predictors of biologic therapeutic drugs like TNF inhibitors are of interest since side effects like serious infections or malignancy cannot be completely ruled out. Response rates are heterogeneous. The present study addressed the question whether in patients with rheumatoid arthritis (RA) interleukin-10 (IL-10) promoter genotypes with potential relevance for IL-10 production capacity are associated with response to long-term treatment with etanercept. Caucasian RA patients that, according to the EULAR criteria, responded well (n = 25), moderately (n = 17) or not (n = 8) to etanercept therapy (median 36 months, range 4–52), and 160 matched controls were genotyped for the IL-10 promoter SNPs -2849 G>A (rs6703630), -1082 G>A (rs1800896), -819 C>T (rs1800871) and -592 C>A (rs1800872). Haplotypes were reconstructed via mathematic model and tested for associations with disease susceptibility and therapy response. We identified the four predominant haplotypes AGCC, GATA, GGCC, and GACC in almost equal distribution. Patients that responded well carried the putative IL-10 low producer allele -2849 A or the haplotypes AGCC and GATA (RR 2.1 and 4.0, respectively; 95% CI 1.1–4.0 and 1.1–14.8), whereas an unfavourable response was associated with carriage of the putative high producer haplotype GGCC (RR 1.9, 95% CI 1.1–3.3). No significant associations of alleles or haplotypes with disease susceptibility were observed. In RA, a low IL-10 production which is genetically determined rather by haplotypes than by SNPs may favour the response to etanercept treatment. Iatrogenic blockade of TNF may reveal proinflammatory effects of its endogeneous antagonist IL-10. Further studies are needed to correlate these genetic findings to direct cytokine measurements.

Survival of human circulating antigen-induced plasma cells is supported by plasma cell-niche cytokines and T follicular helper lymphocytes

Human circulating Ag-induced plasma cells (PCs) contain a high proportion of cycling cells. This study reveals that these PCs spontaneously proliferate in culture during 72 h, as determined by BrdU-uptake detection. Transcriptome analysis indicates that, in comparison with tonsil and bone marrow (BM) PCs, these PCs distinctively upregulate genes involved in cell division. Blood PC proliferation occurs simultaneously with increasing apoptosis rates, and is associated with PC survival. In addition, the proliferating activity of these PCs is enhanced by the addition of cytokines present in PC survival niches. Moreover, blood Ag-induced, but not BM, PCs exhibit the expression of molecules involved in the interaction between memory B cells and T follicular helper (Tfh) cells. In fact, purified circulating and tonsil Tfh cells increased IgG secretion by blood Ag-induced, but not by BM, PCs. This effect is exerted by augmenting blood PC survival through a mechanism partly dependent on cell contact. These results strongly suggest that the proliferating capacity of circulating Ag-induced PCs contributes to their competitive migration to survival niches, either to long-living PC niches or to temporal niches present in reactive lymphoid organs and inflamed tissues, structures where Tfh cells appear to participate.

Association of polymorphisms in interleukin-10 gene promoter with autoantibody production in patients with rheumatoid arthritis

Interleukin-10 (IL-10) is a major anti-inflammatory cytokine that plays a crucial role in the regulation of the immune system. Allelic polymorphisms in the IL-10 gene promoter may contribute to the regulation of autoantibody production. To examine the association between both individuals IL-10 single nucleotide polymorphisms and the production of autoantibodies and the radiographic progression of rheumatoid arthritis (RA), a total of 144 RA patients were recruited into the study. We found significant differences in genotype distribution of the -1082G/A polymorphism between IgG, IgA, and IgM rheumatoid factor(RF)-positive/negative RA patients. We also found significant differences in allelic frequencies of the -3575T/A, -819C/T, and -592A/C polymorphisms between anticyclic citrullinated peptide (anti-CCP)-positive/negative RA patients. The haplotype TGAATA was found to be less frequent within anti-CCP-positive RA patients. Results obtained in this study provide evidence of an association between polymorphisms in IL-10 gene promoter and the production of autoantibodies in RA patients.

Induction of tumour necrosis factor receptor-expressing macrophages by interleukin-10 and macrophage colony-stimulating factor in rheumatoid arthritis

Despite its potent ability to inhibit proinflammatory cytokine synthesis, interleukin (IL)-10 has a marginal clinical effect in rheumatoid arthritis (RA) patients. Recent evidence suggests that IL-10 induces monocyte/macrophage maturation in cooperation with macrophage-colony stimulating factor (M-CSF). In the present study, we found that the inducible subunit of the IL-10 receptor (IL-10R), type 1 IL-10R (IL-10R1), was expressed at higher levels on monocytes in RA than in healthy controls, in association with disease activity, while their expression of both type 1 and 2 tumour necrosis factor receptors (TNFR1/2) was not increased. The expression of IL-10R1 but not IL-10R2 was augmented on monocytes cultured in the presence of RA synovial tissue (ST) cell culture supernatants. Cell surface expression of TNFR1/2 expression on monocytes was induced by IL-10, and more efficiently in combination with M-CSF. Two-color immunofluorescence labeling of RA ST samples showed an intensive coexpression of IL-10R1, TNFR1/2, and M-CSF receptor in CD68+ lining macrophages. Adhered monocytes, after 3-day preincubation with IL-10 and M-CSF, could produce more IL-1beta and IL-6 in response to TNF-alpha in the presence of dibutyryl cAMP, as compared with the cells preincubated with or without IL-10 or M-CSF alone. Microarray analysis of gene expression revealed that IL-10 activated various genes essential for macrophage functions, including other members of the TNFR superfamily, receptors for chemokines and growth factors, Toll-like receptors, and TNFR-associated signaling molecules. These results suggest that IL-10 may contribute to the inflammatory process by facilitating monocyte differentiation into TNF-alpha-responsive macrophages in the presence of M-CSF in RA.

IL-4 and IL-10 modulate autoimmune haemolytic anaemia in NZB mice

New Zealand Black (NZB) mice spontaneously develop autoimmune haemolytic anaemia (AIHA). Here the effect of injecting NZB mice with plasmids encoding IL-4 (pIL-4) or IL-10 (pIL-10) on NZB disease was tested. Both constructs delayed the development of anaemia as judged by increased haematocrit values as compared with controls, but neither altered the IgG1 to IgG2 red blood cell (RBC) bound autoantibody levels. The increased haematocrit value was associated temporally with increased RBC bound IgG in NZB mice treated with pIL-10, but not pIL-4. By contrast, up-regulation of splenic macrophage FcgammaRIIb2 mRNA was associated temporally with increased haematocrit values in NZB mice given pIL-4. However, no such increase occurred in NZB mice that inhaled a peptide containing a dominant T-cell epitope, although this treatment is known to bias the autoimmune response towards Th2 and to reduce the severity of anaemia. It is considered that IL-4 treatment, in part, ameliorates NZB anaemia by increasing the expression of the inhibitory FcgammaRIIb2 and thereby reducing the capacity of splenic macrophages to phagocytose autoantibody coated RBC, but that this mechanism does not explain the beneficial effects of the inhaled peptide.

Interleukin 10 promoter microsatellite polymorphisms are associated with response to long term treatment with etanercept in patients with rheumatoid arthritis

OBJECTIVES

To analyse the association of interleukin 10 (IL10) promoter polymorphisms, which have been shown to be related to IL10 secretion capacity, with the response to long term treatment with etanercept in patients with rheumatoid arthritis (RA).

METHODS

Fifty patients with active RA were treated for up to 4 years (median 39 months, range 3-52) with stable doses of etanercept as monotherapy. Treatment response was assessed as defined by the EULAR criteria in an intention to treat analysis, with the last observation carried forward. IL10 promoter microsatellite polymorphisms IL10.R and IL10.G were genotyped by fragment length analysis in patients and 189 healthy controls matched for ethnicity, age, and sex. Haplotypes were reconstructed using a method based on bayesian, coalescent theory with the PHASE software.

RESULTS

IL10 microsatellite polymorphisms were not associated with susceptibility to RA. When patients with good treatment response (n = 25) were compared with patients with moderate (n = 17) or no response (n = 8), a significantly different distribution of the prevailing alleles R2, R3 and G9, G13, respectively, became evident. Good treatment response was associated with carriage of the R3 allele or R3-G9 haplotype, whereas the allele G13 and the haplotype R2-G13 predominated in patients with moderate or no response.

CONCLUSION

Genotyping of the IL10 promoter microsatellites may be useful in predicting the clinical response to etanercept in patients with RA. The high prevalence of the presumptive IL10 low producer allele R3 in patients with a favourable response suggests that IL10 promotes disease activity in RA under the specific condition of tumour necrosis factor antagonism.

Investigation of an IL-2 polymorphism in patients with different levels of chronic periodontitis

BACKGROUND

Interleukin-2 (IL-2) is a pro-inflammatory cytokine derived from Th1 cells. This cytokine is involved in B-cell activation and stimulates macrophages, natural killer cells, T-cell proliferation and osteoclast activity. IL-2 has been also implicated in the stimulation of osteoclast activity in bone resorption.

OBJECTIVE

In this study the relationship between the polymorphism - 330 (T-->G) in the IL-2 gene and different levels of chronic periodontal disease was investigated.

MATERIAL AND METHODS

DNA was extracted from buccal epithelial cells of 113 unrelated adult individuals acting as controls and with different levels of periodontitis. The PCR-RFLP technique was used to investigate the polymorphism in the promoter of IL-2 gene.

RESULTS

When comparing the data of three groups of patients (Control, Moderate and Severe) we did not find significant differences between the studied IL-2 polymorphism and severity levels of PD. However, when the Control and Moderate phenotypes were grouped together and compared with genotypes TT vs. TG/GG, a significant difference was observed.

CONCLUSION

We conclude that the - 330 (T-->G) polymorphism in the IL-2 gene is associated with the severity of periodontal disease. The results presented in this study suggest an active role of IL-2 in the pathogenesis of periodontal disease.

Interleukin-10 and the interleukin-10 receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Interleukin-10 and the Interleukin-10 Receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Regulation of immunoglobulin secretion by plasma cells infiltrating nasal polyps

OBJECTIVE/HYPOTHESIS

To learn more about the role of plasma cells infiltrating nasal polyps in the pathogenesis of nasal polyposis, we examined their function by analyzing immunoglobulin (Ig) production and the factors implicated in the secretion.

STUDY DESIGN

A series of 19 consecutive nasal polyp tissue samples and, as a control, peripheral blood samples from the same patients, were studied by histopathological and immunological examination.

METHODS

Hematoxylin-eosin and immunohistochemical staining was carried out to identify plasma cells infiltrating nasal polyps. Nasal polyp mononuclear cells (NPMNCs) were purified from nasal polyp tissue samples, and Ig-secreting cells were identified in cytospin preparations stained with fluorescein isothiocyanate-conjugated antibodies against IgA, IgG, IgM, and IgE. Purified NPMNCs were cultured in basal conditions and after the addition of several stimuli. Ig secreted into the culture supernatants was evaluated by an enzyme-linked immunosorbent assay.

RESULTS

Plasma cells accounted for an important fraction of the inflammatory infiltrate. The main Ig isotype synthesized by these cells was IgA, whereas little IgE was detected. In vitro cultures demonstrated that the plasma cells actively secreted Ig for a short period. When cytokine dependence was analyzed, interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-alpha) were shown to be partially responsible for the Ig production. Dependence on CD95-mediated apoptosis was not observed.

CONCLUSIONS

Nasal polyp-infiltrating plasma cells are mainly IgA-secreting cells, the latter property being related to the mucosal immune system. The IgA production is partly dependent on IL-10 and TNF-alpha. The absence of IgE-secreting cells in most of the samples suggests that a type I hypersensitivity reaction is not essential for the development of nasal polyp.

Production of interleukin (IL)-1beta, IL-1 receptor antagonist and IL-10 by blood mononuclear cells in chronic arthritis

Joint erosion is a prevalent feature of rheumatoid arthritis (RA) but not of many other chronic inflammatory arthritides (non-RA). Joint destruction is mediated by cytokines, primarily interleukin (IL)-1 and tumour necrosis factor. Less erosive activity in patients with non-RA compared to RA might be related to factors that inhibit production and/or function of IL-1. Release of IL-1beta, and the two antagonists, IL-1 receptor antagonist (IL-1ra) and IL-10 from blood mononuclear cells were therefore quantitated by ELISA in 22 patients with RA, 11 with non-RA and 15 healthy age-matched controls. Release of IL-1beta was comparable between the three groups but only detectable in cultures stimulated with lipopolysaccharide; it decreased in patients treated with prednisolone: 3.8 ng/10(6)monocytes (median) vs 11.7 (P=0.045). Release of IL-1ra was in all but IgG-stimulated cultures comparable between groups. The ratio of IL-1ra/IL-1beta was elevated in LPS-stimulated cells from RA patients only: 2.0 versus 1.3 (P=0.02). In contrast, IgG-induced IL-1ra release was significantly elevated only in non-RA patients: 95 ng/10(6)monocytes vs 40 (P=0.014), and the levels correlated positively to those of blood CRP (P=0.02). Though stimulated release of IL-10 was similar between the three groups, the levels were lower in non-erosive than erosive arthritis patients, and controls (P=0. 05). In conclusion, increased IgG-stimulated IL-1ra release and elevated IL-1ra/IL-1beta ratio may protect against actions of IL-1 in vivo, and decreased release of IL-10 might be related to features of non-erosive arthritis.

Resistance of Rheumatoid Synovial Dendritic Cells to the Immunosuppressive Effects of IL-10

IL-10 down-regulates the APC function of many dendritic cells (DC), including human peripheral blood (PB) DC. In rheumatoid arthritis (RA), synovial fluid (SF) DC express markers of differentiation and are effective APC despite abundant synovial IL-10. The regulation of DC responsiveness to IL-10 was therefore examined by comparing the effect of IL-10 on normal PB and RA SF DC. Whereas IL-10 down-modulated APC function and MHC class II and B7 expression of PB DC, IL-10 had no such effect on SF DC. Since SF DC have differentiated in vivo in the presence of proinflammatory cytokines, PB DC were cocultured in the presence of IL-10 and either GM-CSF, IL-1β, TNF-α, IL-6, or TGF-β. GM-CSF, IL-1β, and TNF-α were all able to restore APC function. Whereas the effects of IL-10 on PB DC were shown to be mediated by IL-10R1, neither PB nor RA SF DC constitutively expressed IL-10R1 mRNA or detectable surface protein. In contrast, IL-10R1 protein was demonstrated in PB and SF DC whole cell lysates, suggestive of predominant intracellular localization of the receptor. Thus, DC responsiveness to IL-10 may be regulated through modulation of cell surface IL-10R1 expression or signaling.

Interleukin 10 secretion in relation to human IL-10 locus haplotypes

Stimulation of human blood cultures with bacterial lipopolysaccharide (LPS) shows large inter-individual variation in interleukin 10 (IL-10) secretion, which has been shown to have a genetic component of over 70%. Alleles at two microsatellite loci in the 4 kb immediately upstream of the human IL-10 transcription initiation site in 132 individuals from 56 Dutch families were defined and assigned as haplotypes. LPS-induced IL-10 secretion was measured by ELISA and related to the IL-10 promoter haplotypes present in 78 unrelated individuals obtained from these families. Analysis showed that LPS-induced IL-10 secretion from unrelated individuals varied with IL-10 promoter haplotypes (P = 0.024; Kruskal-Wallis test). Two observations were made in relation to secreted IL-10 levels and promoter haplotypes; first, those haplotypes containing the allele IL10.R3 were associated with lower IL-10 secretion than haplotypes containing any other IL10.R allele. Second, the haplotype IL10.R2/IL10.G14 was associated with highest IL-10 secretion overall, whereas the haplotype IL10.R3/IL10.G7 was associated with lowest IL-10 secretion. These data demonstrate that the ability to secrete IL-10 can vary in man according to the genetic composition of the IL-10 locus.

IL-10 as a therapeutic strategy in the treatment of rheumatoid arthritis

IL-10 has anti-inflammatory and immunoregulatory properties that suggest a potential therapeutic role in RA. IL-10 inhibits proinflammatory cytokine and chemokine production in addition to blocking T-cell responses to specific antigens. It acts primarily through inhibition of costimulatory properties of macrophages. IL-10 stimulates proliferation and differentiation of antibody-forming B-cells. Preclinical studies in a variety of animal models, including collagen-induced arthritis, have shown that IL-10 is effective in preventing or inhibiting inflammation and autoreactivity. Although in RA, circulating and synovial levels of IL-10 are increased, accumulated evidence suggests that there may be a relative deficit of available IL-10. Moreover, exogenous addition of IL-10 in vitro has been shown to affect the immunopathological processes involved in RA. Preliminary studies of human recombinant IL-10 in patients with RA have demonstrated a trend towards efficacy with a good safety profile. Taken together, the data support a therapeutic role for IL-10 in the treatment of RA.

IL-10 interrupts memory B cell expansion in the germinal center by inducing differentiation into plasma cells

Germinal center (GC) B cells undergo proliferation, somatic hypermutation and isotype switching in the course of differentiation into plasma cells to produce high-affinity antibodies. To understand the molecular mechanism regulating the expansion of memory B cells and the termination of expansion by differentiation into plasma cells, we investigated the effect of interleukin-2 (IL-2), IL-4, IL-10 and CD40 ligand (CD40L) on the differentiation of GC B cells in the defined culture system containing a follicular dendritic cell (FDC)-like cell line. IL-2, IL-4 and CD40L are required for the optimum proliferation and differentiation of GC B cells. When IL-10 was added to this culture condition, CD20+ CD38+ GC B cells sequentially differentiated into CD20+ CD38- memory B cells and then CD20- CD38+ plasma cells. In the absence of IL-10, the resulting CD20+ CD38- memory B cells continued to proliferate and retained its phenotype. The proliferation of memory B cells was interrupted by addition of IL-10 which induced the differentiation into plasma cells. The expression of CD80 and CD86 was up-regulated in the memory B cells, compared to naive B cells and plasma cells. The identity of memory B cells generated in vitro from GC B cells was further substantiated since memory B cells generated in vivo displayed the identical pattern of proliferation and differentiation under the same culture condition. These results highlight the potent role of GCT helper cells in the expansion and differentiation of memory B cells by regulating different cytokine production.

Pro- and anti-inflammatory cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by the accumulation of inflammatory cells into the synovium and the destruction of joints. Cytokines are important regulators of the synovial inflammation. Some cytokines, such as tumour necrosis factor (TNF)-alpha and interleukin (IL)-1, function by promoting inflammatory responses and by inducing cartilage degradation. Other cytokines, such as IL-4, IL-10 and IL-13, function mainly as anti-inflammatory molecules. Although anti-inflammatory cytokines are present in rheumatoid joints, in progressive RA their levels obviously are too low to neutralize the deleterious effects of proinflammatory cytokines. Inhibiting the action of proinflammatory cytokines by using specific cytokine inhibitors or anti-inflammatory cytokines is the basis for new therapies currently tested in patients with RA. Promising results on the use of neutralizing anti-TNF-alpha monoclonal antibodies in the treatment of RA have been reported. The results from a trial using recombinant IL-10 in the treatment of patients with RA are available in the near future and will be important in determining the therapeutic potential of this cytokine.

Dysregulation of interleukin-10 production in relatives of patients with systemic lupus erythematosus

OBJECTIVE

To evaluate interleukin-10 (IL-10) production in relatives of patients with systemic lupus erythematosus (SLE).

METHODS

Production of IL-10 was evaluated in 13 families in which several members had SLE. The constitutive IL-10 production in SLE patients (n = 16) was compared with that in healthy members of these multiplex families (n = 70), in 30 SLE patients who had no relatives with SLE, and in 46 healthy unrelated controls.

RESULTS

The level of IL-10 production did not differ between SLE patients who were members and those who were not members of multiplex families (mean +/- SEM 4,384 +/- 908 pg/ml and 4,709 +/- 560 pg/ml, respectively), but was higher in both groups than in healthy unrelated controls (515 +/- 88 pg/ml). The healthy members of the multiplex families constitutively produced large amounts of IL-10 (3,080 +/- 311 pg/ml; P < 0.001 compared with healthy unrelated controls). This high IL-10 production was independent of age and sex, and was similar in first- and second-degree relatives of SLE patients. The IL-10 was produced both by monocytes and by a subpopulation of B lymphocytes in SLE patients and in their relatives.

CONCLUSION

The dysregulation of IL-10 production previously identified in SLE patients is also present in healthy members of families with several cases of SLE, and it may contribute to the immunologic abnormalities affecting relatives of SLE patients.

Cytokines in autoimmunity

The past few years have witnessed exciting developments regarding the role of cytokines in autoimmune diseases, particularly in rheumatoid arthritis and Crohn's disease, with the demonstration that anti-TNF alpha therapy is clinically beneficial and provides reproducible results. Recent contributions to this field, derived from in vivo studies in animal models of autoimmunity, and increasingly from clinical trials, have greatly enhanced our understanding of this field.