Relationship between HLA polymorphisms and gamma interferon and interleukin-10 cytokine production in healthy individuals after rubella vaccination

We studied the association between HLA alleles and rubella-specific gamma interferon (IFN-gamma) (Th1) and interleukin-10 (IL-10) (Th2) cytokine responses among 106 healthy children (ages, 14 to 17 years) previously immunized with two doses of rubella vaccine. Antibody titers and cytokine responses to rubella vaccination were not sex or age dependent. Several class I HLA-A (*0201, *2402, *6801) alleles were significantly associated with rubella vaccine-induced IFN-gamma secretion. Several class II HLA-DRB1 (*0101) and HLA-DQB1 (*0501) alleles were also suggestive of an association with IFN-gamma secretion. Alleles with potential associations with rubella-specific IL-10 production included HLA-A (*0201, *6801), HLA-B (*4901), and HLA-DRB1 (*1302). The class I A*0201 and A*6801 alleles were associated with both IFN-gamma and IL-10 secretion. These tentative associations need to be validated in larger studies with subjects of differing ethnicities. These results provide additional evidence that HLA genes may influence Th1- and Th2-specific cytokine response(s) following rubella immunization, which in turn can influence both cellular and humoral immune responses to rubella vaccination.     

Ultraviolet-irradiated apoptotic lymphocytes produce interleukin-10 by themselves

Since inflammatory responses are rarely associated with apoptotic cell death, it is plausible that cells undergoing apoptosis may signal the immune system to suppress inflammatory responses. By employing intracytoplasmic cytokine staining in conjunction with annexin V-binding, we examined the representative pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) and anti-inflammatory cytokine interleukin-10 (IL-10) expression in ultraviolet (UV)-irradiated lymphocytes and analyzed them with apoptosis induction at a single cell level. We show here that lymphocytes exposed to UV resulted in IL-10 expression with marginal TNFalpha expression, and these IL-10-expressing cells underwent apoptosis. Addition of inhibitors for caspases blocked UV-induced apoptosis but not IL-10. These results indicate that UV elicited at least two types of signals: one which was caspase dependent, leading to apoptosis; and another which was caspase independent, leading to IL-10 production. Lymphocyte apoptosis was thus found to link anti-inflammatory cytokine secretion, and thereby may contribute to preventing unwanted immune responses.     

Genetic contribution of the interleukin-10 promoter polymorphism in endometriosis susceptibility

PROBLEM: Interleukin-10 (IL-10) is an important immunomodulatory cytokine. The aim of this study was to investigate whether polymorphisms of the IL-10 gene promoter polymorphisms may be responsible in part for genetic susceptibility to endometriosis. METHODS OF STUDY: Polymorphisms at position -1082 and -592 in the IL-10 promoter region were determined in 196 patients with endometriosis and 160 fertile healthy women by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). RESULTS: There were no statistically significant differences in the genotype and allele frequencies of IL-10 promoter polymorphism between the endometriosis and control groups. However, when subgrouped according to clinical features, the frequencies of the -592*CC genotype and -592*C allele were significantly increased in patients with autoantibodies to carbonic anhydrase II (anti-CA II ab) compared with controls. CONCLUSION: IL-10 promoter polymorphisms were associated with the production of anti-CA II ab in patients with endometriosis, suggesting a role in the genetic susceptibility for endometriosis.     

Hypophysectomy enhances interleukin-1beta, tumor necrosis factor-alpha, and interleukin-10 mRNA expression in the rat brain.

Although the effects of various cytokines as regulators of hormone synthesis and production are well documented, the role for pituitary hormones as modulators of cytokine synthesis is not fully understood. In this study, we investigated the effect of pituitary hormones' depletion on cytokine synthesis after short- (21 days) and long- (35 days) term hypophysectomy (ST-HX and LT-HX, respectively). The expresssion of the proinflammatory cytokine interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory cytokines IL-10 and transforming growth factor-beta (TGF-beta) in the rat brain was studied using in situ hybridization. Our results indicate that IL-1beta mRNA-expressing cells were significantly upregulated at day 21 in hypophysectomized rats compared to sham-operated controls. This enhanced expression was also detected later at day 35 post hypophysectomy. However, TNF-alpha mRNA expression was significantly increased only at the later sampling interval. IL-10 mRNA-expressing cells were increased after long-term hypophysectomy compared to controls. TGF-beta mRNA-expressing cells were not increased after hypophysectomy. In conclusion, these results suggest a role for pituitary hormones in IL-1beta, TNF-alpha, and IL-10 synthesis.     

The complex role of interleukin-10 in autoimmunity

Interleukin-10 (IL-10) is a cytokine that has been tested in different clinical trials based on its ability to down regulate T helper 1-type responses, namely IFN-gamma secretion and activation of monocytes/macrophages. There is also evidence in different animal models, that IL-10 could be useful in controlling Th2-mediated inflammatory processes. However, IL-10 also displays immunostimulatory properties especially on B cells and activated CD8(+)T cells. These seemingly divergent effects may explain the apparent lack of activity or adverse effects observed after IL-10 treatment in several animal models or clinical trials. Nevertheless, the ability of IL-10 to induce the differentiation of a subset of regulatory CD4(+)T cells (Tr1) and the importance of IL-10 for the in vivo function of regulatory T cells tends to support the view of IL-10 as a crucial cytokine in the control of immune responses. In different in vivo models, these cells were shown to inhibit Th1 and Th2-type inflammatory responses through the secretion of IL-10. These Tr1 cells may thus be used in specific cellular therapy in order to deliver IL-10 precisely at the site of inflammation.     

Renovascular disease is associated with low producer genotypes of the anti-inflammatory cytokine interleukin-10

Cytokines are important mediators of inflammatory and proliferative responses in disease states including atherosclerosis. Genetic variations in cytokine production could potentially influence the outcome of these responses. The aim of this study was to determine whether cytokine gene polymorphism might influence the development of atherosclerotic renal artery stenosis. Sixty-six patients with atherosclerotic renal artery stenosis and 100 normal healthy individuals were genotyped for interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-2 promoter region polymorphism. TNF-a, TNF-d, and IL-10 microsatellite polymorphisms were also analyzed. The frequency of the anti-inflammatory cytokine IL-10 promoter (-1082 A positive) GA and AA genotypes which are associated with low production were higher in the patient group when compared to the control group. The AA-TT-AA homozygous genotype combination of three single-nucleotide polymorphisms at -1082, -819, and -592 in the IL-10 gene was also observed at a higher frequency in the patient group compared to the controls. The frequency of TNF-alpha, IL-6, and IL-2 polymorphisms did not show any significant difference between the patient and control groups. To correlate IL-10 genotypes with differences in IL-10 protein expression, in vitro mRNA and protein levels were analyzed in lipopolysaccharide-stimulated peripheral blood mononuclear cells from 22 patients with renal artery stenosis and 33 controls. Individuals genotyped as A positive at position -1082 produced lower levels of IL-10 protein and had lower copy numbers of mRNA when compared to individuals genotyped as A negative in both patient and control groups. The increased frequency of the low producer IL-10 promoter, -1082 A-positive genotype in patients with renal artery stenosis, suggests that IL-10 may protect against the development of atherosclerotic renovascular disease.     

Depletion of endogenous interleukin-10 augments interleukin-1 beta secretion by Mycobacterium bovis BCG-reactive human cells.

In this study, we found evidence that the interleukin-10 (IL-10) protein is functionally relevant in Mycobacterium bovis BCG-induced cytokine synthesis, as neutralization of endogenously synthesized IL-10 in human cells activated with BCG resulted in a two- to threefold increase in the level of IL-1 beta. When exogenous recombinant human IL-10 was added to human mononuclear cells, a significant reduction of BCG-induced IL-1 beta secretion was observed. This inhibitory effect was not attributed to a cytotoxic effect, since trypan blue exclusion studies indicated no loss of cell viability in the presence of IL-10, and it was specific, as it was completely abolished in the presence of anti-IL-10 neutralizing monoclonal antibody while an irrelevant antibody used as a control had no effect. Taken together, these are the first studies that demonstrate that the depletion of endogenous IL-10 via anti-IL-10 antibody results in a very significantly enhanced BCG-induced IL-1 beta secretion and that the addition of exogenous IL-10 to human mononuclear cells stimulated with BCG inhibits IL-1 beta production. Further experimental work is needed to determine if the neutralization of IL-10 activity via anti-IL-10 antibody indeed enhances cytokine synthesis in vivo. However, the present results may be of importance, since the use of anti-IL-10 antibody could presumably contribute to the protective immunity induced by BCG against tuberculosis via an increase in cytokine synthesis that would amplify antimicrobial systems.     

Inhibitory effects of interleukin-10 on synovial cells of rheumatoid arthritis.

This paper describes the immunoregulatory effects of interleukin-10 (IL-10) on synovial cells in vitro. Synovial cells were cultured with IL-10 in the presence or absence of various cytokines. Following incubation, the costimulatory molecule expression on synovial cells and cytokine production in culture supernatants were analysed by an indirect immunofluorescence method and enzyme-linked immunosorbent assay, respectively. We also examined the effect of IL-10 on the function of synovial cells as antigen-presenting cells (APC). Synovial cells spontaneously express several kinds of costimulatory molecule and produce various kinds of cytokines. Stimulation of synovial cells with interferon-gamma (IFN-gamma), IL-1 beta, or 12-O-tetradecanoyl phorbol 13-acetate (TPA) markedly enhanced the expression of costimulatory molecules and cytokine production of these cells. Both spontaneous and up-regulated costimulatory molecule expression and cytokine production were significantly suppressed by the addition of IL-10. Autologous T-cell proliferation was stimulated by purified protein derivative (PPD) in IFN-gamma-treated synovial cells and treatment of these synovial cells with IL-10 also suppressed T-cell proliferation. Our results suggest that IL-10 has an inhibitory effect on synovial cells and is an important immunoregulatory component of the cytokine network in rheumatoid arthritis.     

Functional characterization of human IL-10.

Rapid progress has been made over the past two years in the characterization of the biological activities of interleukin-10. Interleukin-10, produced by T cells, B cells, macrophages/monocytes and keratinocytes, alters profoundly the morphology, the expression of MHC class II antigens and the production of cytokines by monocytes which in turn can affect a variety of immunological responses including antigen specific proliferation and cytokine production of both soluble and allo-antigens by T cells, cytokine production by natural killer cells and immunoglobulin production by B cells. IL-10 also directly affects the function and growth of T cells, B cells and mast cells. These characteristics indicate that IL-10 has strong anti-inflammatory activities and may act as a general suppressor factor of immune reactions with consequences for transplantation, tolerance, cancer therapy and infectious diseases.     

Placental tissue interleukin-10 receptor distribution in pre-eclampsia

PROBLEM: Reduced placental (trophoblast) cytokine interleukin-10 (IL-10) occurs in human pre-eclampsia. Along with an increase in inflammatory cytokines this may play an important role in the development of hypertension in pregnancy. It is not clear whether the changes in placental IL-10 are due to a change in the placental cell production of IL-10 or a result of changes in cytokine receptor status in adjacent tissues. This study is aimed at qualifying the presence and distribution of IL-10 receptors in women with a pre-eclamptic outcome compared to normal pregnancy and gestational hypertension. METHOD OF STUDY: Patients at the KGV Hospital, Sydney was selected for the study. Placentas were collected fresh and paraffin serial sections made. Sections were stained with IL-10 receptor antibody (10 microgram/mL) using avidin-biotin immunohistochemistry. Tissues of patients with pre-eclampsia (n=11) were compared with normal pregnancy (n=12). Pre-eclampsia was defined as a blood pressure >140/90 mmHg on two occasions and de nova proteinuria >300 mg per day which resolved post-partum. The fetal weights, gestational ages and maternal ages at delivery were compared (ANOVA) and the differences in staining of decidual and villous tissues were graded according to density. Statistical comparisons were made using the Kruskal-Wallis test. RESULTS: The groups were similar for maternal gestational age but delivered at earlier gestation and with lower fetal weight. There was significantly less villous cytotrophoblast staining for IL-10 receptor in all groups (P=0.012) compared to decidual trophoblast cells. There was equal intensity and density of extravillous straining observed in normal pregnancy (45 +/- 12%) positive cells compared to pre-eclampsia (27 +/- 12%). CONCLUSION: IL-10 receptors are present in greater concentration in the extravillous (decidual) trophoblast compared to villi. The decrease in IL-10 produced by trophoblast cells in pre-eclampsia is not explained by a difference in the IL-10 receptor distribution compared to normal pregnancy.     

STAT-1-mediated repression of monocyte interleukin-10 gene expression in vivo

There have been substantial advances in understanding the events that regulate gene expression at the cellular and molecular level; however, there has been limited progress integrating this information to understand how biological systems function in vivo. For example, the anti-inflammatory cytokine IL-10 is thought to down-regulate the effects of the pro-inflammatory cytokine IFN-gamma on monocyte activation following LPS stimulation. However, the often-postulated reciprocal regulation of IL-10 gene expression by IFN-gamma has not been studied in vivo. Here we demonstrate that the regulation of IL-10 gene expression has at least two phases following challenge with LPS or a gram-negative organism. In C57BL/6 mice, early IL-10 induction occurs independently of STAT-1, while a delayed active repression of IL-10 gene expression is critically dependent on STAT-1, but only partially dependent upon IFN-alpha/beta and IFN-gamma. This in vivo IL-10 production comes from blood monocytes, but not tissue macrophages, and cannot be reproduced in vitro. This study provides new insights into the regulation of IL-10 following challenge with a gram-negative organism, and highlights the importance of studying these cytokine regulatory pathways in vivo.     

Effect of interleukin-10 on dendritic cell maturation and function

The main function of dendritic cells (DC) is to induce the differentiation of naive T lymphocytes into helper cells producing a large array of lymphokines, including interleukin (IL)-2; interferon-γ (IFN-γ), IL-4, IL-5 and IL-10. The potent immunostimulatory properties of DC develop during a process of maturation that occurs spontaneously in vitro. Since IL-10 has been shown to inhibit Th1 responses, we determined its effect on DC maturation and accessory function. Our data show that DC that have undergone maturation in vitro in the presence of IL-10, have an impaired capacity to induce a Th1-type response in vivo, leading to the development of Th2 lymphocytes. Their inability to promote the synthesis of IFN-γ seems to correlate with a decreased production of IL-12, an heterodimeric cytokine necessary for optimal generation of Th1-type cells. These results suggest that IL-10 skews the Th1/Th2 balance to Th2 in vivo by selectively blocking IL-12 synthesis by the antigen-presenting cells that play a role of adjuvant of the primary immune response. The cytokines present in the environment at the presentation step may, therefore, determine the class of the immune response induced by DC in vivo, i.e. Th0 Th1 and/or Th2.     

Divergent effects of interleukin-10 on cytokine production by mononuclear phagocytes and endothelial cells

Interleukin-10 (IL-10), a product of T helper type 2 (TH2) cells and monocytes, inhibits cytokine production in mononuclear phagocytes. Given the similarities and interrelationship between cells of the monocyte-macrophage lineage and endothelial cells, we examined the effects of IL-10 on vascular endothelium. Murine IL-10 induced low levels of IL-6 production and amplified induction of IL-6 by lipopolysaccharide (LPS) or IL-1 in the murine tEND.1 endothelioma line, used for these studies because it retains properties of normal endothelium. The effect was more evident after prolonged (48–72 h) exposure to IL-10. IL-10 had similar activity on other endothelioma lines, whereas it inhibited IL-6 production by peritoneal macrophages. Induction and amplification of cytokine production by IL-10 was associated with higher levels of mRNA, which were maintained longer (up to 48 h) than in controls. In addition to IL-6, murine IL-10 induced or amplified expression of the chemoattractant cytokines monocyte chemotactic protein-1 (MCP-1) and KG Human IL-10 inhibited IL-6 release by LPS-stimulated human peripheral blood mononuclear cells, whereas it did not interfere with cytokine production by LPS- or IL-1-stimulated human umbilical vein endothelial cells. The selective inhibitory action of IL-10 on mononuclear phagocytes versus endothelial cells may play a role in the pathophysiology of TH2-directed responses.     

IL-10 expression profiling in human monocytes

Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine with numerous immunomodulatory effects, including the inhibition of proinflammatory cytokine production. The mechanisms by which IL-10 exerts these effects still remain largely unknown. As there is evidence that suggests IL-10-mediated cytokine suppression requires the induction of an intermediate gene, we have used gene-chip technology to identify IL-10-inducible genes in human monocytes. We have been able to identify a total of 19 genes that are up-regulated in response to IL-10. Three of these genes had been identified previously: IL-1ra, suppressors of cytokine signaling-3, and CD163; however, the other 16 represent newly identified IL-10-responsive genes. Further analysis of the regulation of eight of these genes showed a remarkable specificity to regulation by lipopolysaccharides (LPS) and IL-10, but not by other anti-inflammatory mediators such as IL-4 and transforming growth factor-beta, suggesting that two diverse stimuli such as IL-10 and LPS may engage common signaling mechanisms.