Inhibition of IL-10 expression by IFN-gamma up-regulates transcription of TNF-alpha in human monocytes

Stimulation of human monocytes with LPS induces expression of multiple cytokines, including TNF-alpha, IL-1 beta, IL-6, and IL-10, IL-10 expression is delayed relative to that of TNF-alpha, IL-1 beta, and IL-6. Furthermore, IL-10 feedback inhibits expression of TNF-alpha, IL-1 beta, and IL-6, thus providing an efficient autocrine mechanism for controlling proinflammatory cytokine production in monocytes. The Th1-type lymphokine, IFN-gamma, markedly up-regulates TNF-alpha production in monocytes. However, the precise mechanism by which IFN-gamma mediates this effect is unknown. We examined the effects of IFN-gamma on IL-10 expression in LPS-stimulated monocytes, and the relationship between IL-10 and TNF-alpha production in these cells. LPS stimulation induced rapid, ordered expression of multiple cytokines. Steady-state mRNA levels for TNF-alpha increased rapidly, reached maximal levels by 2 to 3 h poststimulation, and then declined sharply. IL-1 beta and IL-6 mRNA levels also increased markedly following stimulation with LPS, but decreased more slowly than did TNF-alpha. Down-regulation of mRNA for TNF-alpha, IL-1 beta, and IL-6 coincided with a delayed and more gradual increase in IL-10 mRNA levels. Furthermore, neutralization of IL-10 with anti-IL-10 Abs prolonged TNF-alpha mRNA expression, and significantly increased net TNF-alpha production. IFN-gamma suppressed expression of IL-10 mRNA and protein in a dose-dependent manner. Moreover, inhibition of IL-10 production correlated with a marked increase in both the magnitude and duration of TNF-alpha expression. Thus, potentiation of TNF-alpha production by IFN-gamma in monocytes is coupled to inhibition of endogenous IL-10 expression.     

Hypoxia stimulates cytokine production by villous explants from the human placenta

It has been hypothesized that inadequate placentation in the hypertensive disorder of pregnancy known as preeclampsia creates foci of placental ischemia/hypoxia leading to the elaboration of factors that compromise systemic endothelial function to produce disease sequelae. As tumor necrosis factor-alpha (TNF alpha) and interleukin-1 (IL-1) are inflammatory cytokines capable of eliciting endothelial cell dysfunction, we investigated whether the production of these inflammatory cytokines by cultured villous explants from the human placenta was affected by incubation in reduced oxygen (2% O2). The term placenta produced TNF alpha, IL-6, and low levels of IL-1alpha and IL-1beta under standard tissue culture conditions. Hypoxia significantly increased TNF alpha, IL-1alpha, and IL-1beta production by 2-, 6-, and 23-fold, respectively, but did not affect IL-6 production. Further, cytokines were immunolocalized to the syncytiotrophoblast layer as well as to some villous core cells. Hypoxic regulation of placental TNF alpha and IL-1beta production also appeared to differ based on gestational age. Finally, treatment with either cobalt chloride or an iron chelator mimicked the hypoxic response, suggesting that stimulation of placental cytokine production may involve a heme-containing, O2-sensing protein. These results suggest that placental hypoxia can lead to the elaboration of inflammatory cytokines, which may contribute to the pathophysiology of preeclampsia.     

Adult-onset energy restriction of rhesus monkeys attenuates oxidative stress-induced cytokine expression by peripheral blood mononuclear cells

We previously reported that energy restriction (ER) of mice attenuated age-associated increases in serum levels of interleukin-6 (IL-6). Here, we studied peripheral blood mononuclear cells (PBMC) from male rhesus monkeys to investigate the following: 1) the production of IL-6 and other cytokines become dysregulated with aging; 2) ER influences cytokine production and mRNA expression; and, 3) oxidative stress, as induced in vitro by xanthine and xanthine oxidase (X/XOD), influences cytokine mRNA and protein levels. Two types of comparisons were made as follows: 1) between normally fed young (6-9 y) and old monkeys (22-33 y); and 2) between middle-aged monkeys (15-21 y) fed either a normal energy intake or subjected to ER (for 5.5 y at 30% less than base-line intake). IL-6 protein levels and X/XOD-induced IL-6 mRNA levels in PBMC from old monkeys were significantly greater than those in PBMC from young animals. In contrast, interleukin-1beta (IL-1beta) and interleukin-8 mRNA levels were not strongly influenced by advancing age. X/XOD, which increased levels of protein carbonyls (indicative of oxidative damage) in PBMC, induced the expression of all three cytokines. ER reduced IL-6 protein and mRNA levels induced by X/XOD and the unstimulated mRNA levels of IL-1beta. These results indicate that, in a nonhuman primate model, oxidative stress may contribute to age-associated increases in the levels of certain cytokines and that adult-onset ER partially ameliorates this alteration.     

Pulmonary and hepatic gene expression following cecal ligation and puncture: monophosphoryl lipid A prophylaxis attenuates sepsis-induced cytokine and chemokine expression and neutrophil infiltration

Polymicrobial sepsis induced by cecal ligation and puncture (CLP) reproduces many of the pathophysiologic features of septic shock. In this study, we demonstrate that mRNA for a broad range of pro- and anti-inflammatory cytokine and chemokine genes are temporally regulated after CLP in the lung and liver. We also assessed whether prophylactic administration of monophosphoryl lipid A (MPL), a nontoxic derivative of lipopolysaccharide (LPS) that induces endotoxin tolerance and attenuates the sepsis syndrome in mice after CLP, would alter tissue-specific gene expression post-CLP. Levels of pulmonary interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), granulocyte colony-stimulating factor (G-CSF), IL-1 receptor antagonist (IL-1ra), and IL-10 mRNA, as well as hepatic IL-1beta, IL-6, gamma interferon (IFN-gamma), G-CSF, inducible nitric oxide synthase, and IL-10 mRNA, were reduced in MPL-pretreated mice after CLP compared to control mice. Chemokine mRNA expression was also profoundly mitigated in MPL-pretreated mice after CLP. Specifically, levels of pulmonary and hepatic macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, MIP-2, and monocyte chemoattractant protein-1 (MCP-1) mRNA, as well as hepatic IFN-gamma-inducible protein 10 and KC mRNA, were attenuated in MPL-pretreated mice after CLP. Attenuated levels of IL-6, TNF-alpha, MCP-1, MIP-1alpha, and MIP-2 in serum also were observed in MPL-pretreated mice after CLP. Diminished pulmonary chemokine mRNA production was associated with reduced neutrophil margination and pulmonary myeloperoxidase activity. These data suggest that prophylactic administration of MPL mitigates the sepsis syndrome by reducing chemokine production and the recruitment of inflammatory cells into tissues, thereby attenuating the production of proinflammatory cytokines.     

Localization of mRNA for inflammatory cytokines in radicular cyst tissue by in situ hybridization, and induction of inflammatory cytokines by human gingival fibroblasts in response to radicular cyst contents

The expression of mRNA encoding the inflammatory cytokines interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor alpha(TNF-alpha) have been examined in radicular cysts by in situ hybridization. Furthermore, the biological activity of the contents of radicular cysts (RCC) has been assayed by adding extracts of RCC to cultured human gingival fibroblasts (HGFs) and analyzing the culture medium for the release of inflammatory cytokines. In the epithelial layer, keratinocytes expressed all cytokine mRNAs examined at various levels. Basal layer cells expressed mRNA for each cytokine. In the subepithelial granulation tissue of the cysts, fibroblasts and macrophages expressed mRNA for IL-6, IL-8, IL-1beta and TNF-alpha mRNA at varying levels; especially clear expression of TNF-alpha and IL-1beta mRNA was detected on macrophages. The infiltrating lymphoid cells, largely composed of T cells and plasma cells, expressed these cytokine mRNAs, especially those encoding IL-6 and IL-8, at various levels. In vitro analysis indicated dose-dependent release of both IL-6 and IL-8 by HGFs in response to RCC. After heating to 100 degrees C for 10 min, RCC almost completely failed to stimulate IL-6 release from HGFs. Furthermore, anti-IL-1beta antibody (neutralization test) did not prevent the stimulation of IL-6 release by RCC. Significant amounts of IL-6 and IL-8 were detected in RCC in two cases, and a trace amount of IL-1beta was detected in one case. This study demonstrated the wide expression of mRNA encoding inflammatory cytokines in radicular cyst tissues, and RCC itself was capable of stimulating IL-6 and IL-8 production from HGFs.     

Mg2+ coordination in catalytic sites of F1-ATPase

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) and inflammatory cytokines on regulation of interleukin-6 (IL-6) production by human gingival fibroblasts (HGF). The HGF cell lines used in this study, H-CL and F-CL, were established by the explant technique from healthy gingival tissue. Cultured cells were grown to confluency and incubated with various concentrations of LPS from Escherichia coli or Porphyromonas gingivalis or with the recombinant human cytokine tumor necrosis factor alpha (TNF-alpha), IL-1alpha, or IL-1beta. Culture supernatants were collected at various times and assessed for IL-6 production by enzyme-linked immunosorbent assay. Total RNA was isolated from the harvested cells and used to assess levels of IL-6 mRNA by the RNase protection assay. Both LPS preparations induced IL-6 production (1 to 4 ng of IL-6 per ml) by both HGF cell lines. Although TNF-alpha stimulated IL-6 production by HGF, > 10-fold-larger amounts were induced with IL-1alpha and IL-1beta. Furthermore, the addition of both IL-1alpha and TNF-alpha to cultured cells resulted in approximately 600- to 800-fold-higher levels of IL-6 than seen in control cultures, suggesting that these cytokines synergistically induced IL-6 production by HGF. IL-6 message in cultured cells was upregulated 20-fold by TNF-alpha, 1,000-fold by IL-1alpha and IL-1beta, and 1,400-fold by IL-1alpha plus TNF-alpha. IL-1alpha and TNF-alpha alone upregulate IL-6 production in a dose- and time-dependent fashion. The addition of IL-1alpha and TNF-alpha to cultured HGF cells resulted in a synergistic induction of IL-6 after 8 h of incubation and when greater than 10 pg of this combination per ml was used. Our studies show that inflammatory cytokines are hundreds of times more potent than LPS in stimulating IL-6 production by HGF.     

Fourier analysis of nucleotide sequences. Periodicity in E. coli promoter sequences

The synthesis of proinflammatory cytokines involves members of the mitogen-activated protein (MAP) kinase stress pathway, particularly p38 MAP kinase and c-jun NH2-terminal kinase. In this report we used hyperosmotic stress to study changes in steady-state mRNA levels and synthesis of proinflammatory cytokines in freshly obtained human peripheral blood mononuclear cells (PBMC) in vitro. There was no evidence of interleukin (IL)-8 gene expression in freshly obtained human blood despite 30 cycles of amplification of reverse-transcribed mRNA using the polymerase chain reaction. In contrast, exposure of PBMC to hyperosmotic conditions (330-410 mOsM) by the addition of NaCl to tissue culture medium induced gene expression for IL-1 alpha, IL-1 beta, and IL-8. Routine tissue culture medium is hyperosmotic (305 mOsM) compared to human plasma (280-295 mOsM), but decreasing the osmolarity to the physiological range resulted in a 50% reduction in baseline IL-8 synthesis (P < 0.001). Although hyperosmotically induced accumulation of steady-state mRNA levels for IL-1 alpha and IL-1 beta increased 50- and 7-fold over control, respectively, these were poorly translated into each respective cytokine. However, in PBMC stimulated by hyperosmotic stress, the addition of femtomolar concentrations of bacterial lipopolysaccharide, IL-1, or 1% normal human serum resulted in a synergistic synthesis (at least twice that expected) of IL-1 alpha, IL-1 beta, TNF-alpha, and IL-8.     

Dimethoxyphenylethylamine and tetrahydropapaverine are toxic to the nigrostriatal system

Experimental allergic neuritis (EAN) is a T cell mediated animal model of Guillain-Barré syndrome, characterized by inflammation and demyelination of the peripheral nervous system (PNS). To study the involvement of immunoregulatory cytokines, we induced EAN in Lewis rats by immunizing with bovine PNS myelin (BPM) and Freund's complete adjuvant. mRNA expression of the cytokines IL-1beta, IL-6, IL-10, IL-12, TNF-alpha and TNF-beta, and the cytolytic effector molecule cytolysin was examined in lymph node mononuclear cells (MNC) over the course of EAN by in situ hybridization after culture without antigen and in the presence of BPM, the myelin P2 protein, the control antigen acetylcholine receptor, or the mitogen PHA. Three patterns of cytokine mRNA expressing MNC in relation to clinical EAN could be distinguished: (i) IL-1beta mRNA expressing cells peaked already on day 3 post immunization (p.i.), and BPM- and P2-reactive TNF-alpha, and BPM-reactive IL-6 mRNA expressing cells were also detected already on day 7 p.i., i.e., before onset of clinical EAN; (ii) BPM- and P2-reactive TNF-alpha peaked together with P2-reactive TNF-beta, IL-6 and IL-12 mRNA expressing cells at height of clinical EAN, consistent with a disease-promoting role for these four cytokines; (iii) high levels of BPM- and P2-reactive IL-10 and cytolysin mRNA expressing cells were observed only during recovery (day 28 p.i.), consistent with a disease down-regulating role of IL-10 and cytolysin. The results suggest a major proinflammatory role for IL-1beta, TNF-alpha, TNF-beta, IL-6 and IL-12 and a disease down-regulating function of IL-10 as well as cytolysin in EAN.     

Magnetic ordering in the three-dimensional site-disordered Heisenberg model

The role of oncostatin M (OM) in modulating production of cytokines by connective tissue cells is largely unexplored. We have examined the effects of stimulating fibroblast cultures derived from human synovium and from normal lung with OM alone or in combination with IL-1, IL-1 alpha (or IL-1 beta) at 1 or 5 ng/ml, stimulated production of high levels of granulocyte-macrophage CSF (GM-CSF), IL-8, and IL-6 protein. At various concentrations (0.1-50 ng/ml), OM alone failed to significantly enhance protein or mRNA levels of GM-CSF, IL-8, IL-6, or G-CSF after 18 h of stimulation. When combined with IL-1 alpha or -beta, OM caused a dose-dependent inhibition of the IL-1-induced level of IL-8 and GM-CSF protein and mRNA expression, whereas IL-6 production was simultaneously enhanced. In contrast, when IL-6 or leukemia inhibitory factor (two other cytokines that share gp130 receptor components with OM) were used in a similar fashion in combination with IL-1 alpha, neither cytokine consistently altered the IL-1-induced levels of IL-8, GM-CSF, or IL-6. In addition, only OM and not IL-6 or leukemia inhibitory factor was able to induce STAT-1 nuclear factor binding to DNA in stimulated fibroblast extracts as measured by electrophoretic mobility shift assay. These results suggest that OM can significantly alter cytokine profiles of stimulated fibroblasts and may play a unique role in modulating cytokine production by these cells at sites of inflammation.     

Cytokine induction in murine macrophages infected with virulent and avirulent Rhodococcus equi

To look for a possible correlation between the virulence of Rhodococcus equi and its cytokine-inducing capacity, we evaluated intracellular survival and measured cytokine induction by mouse macrophages infected with a virulent strain containing an 85-kb plasmid and expressing VapA (103+), its avirulent plasmid-cured derivative (103-), and heat-killed 103+ (HK). After incubation with similar numbers of bacteria, macrophages infected with 103- contained significantly more organisms than those infected with 103+ or HK. The number of bacteria in the macrophages infected with 103- and HK decreased progressively, whereas the 103+ numbers remained constant over 48 h. Interleukin 1beta (IL-1beta), IL-6, IL-10, IL-12 p40, and tumor necrosis factor alpha (TNF-alpha) mRNA induction peaked at 4 h and returned to baseline between 12 and 48 h postinfection. IL-1beta, IL-6, IL-10, and TNF-alpha concentrations assessed by enzyme-linked immunosorbent assay generally agreed well with mRNA expression; IL-12 could, however, not be detected. For all the cytokines detected, mean concentrations in the supernatants were consistently higher in the 103(-)-infected monolayers than in those infected with 103+, although, with the exception of IL-1beta, the differences were not statistically significant. R. equi HK was a poor inducer of cytokine production. In conclusion, virulent and avirulent R. equi strains induced similar levels of cytokine synthesis. The slightly greater induction of most cytokines observed following infection with 103- is likely secondary to greater uptake by macrophages rather than to a direct role of VapA or another plasmid-encoded product in downregulating cytokine induction.     

Lactobacilli and streptococci induce interleukin-12 (IL-12), IL-18, and gamma interferon production in human peripheral blood mononuclear cells

Human peripheral blood mononuclear cells (PBMC) were stimulated with three nonpathogenic Lactobacillus strains and with one pathogenic Streptococcus pyogenes strain, and cytokine gene expression and protein production were analyzed. All bacteria strongly induced interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor alpha mRNA expression and protein production. S. pyogenes was the most potent inducer of secretion of IL-12 and gamma interferon (IFN-gamma), and two of three Lactobacillus strains induced IL-12 and IFN-gamma production. All strains induced IL-18 protein production. IL-10 and IL-4 production was induced weakly and not at all, respectively. Our data show that nonpathogenic lactobacilli and pathogenic streptococci can induce Th1 type cytokines IL-12, IL-18, and IFN-gamma in human PBMC.     

Individual cell analysis of the cytokine repertoire in human immunodeficiency virus-1-infected monocytes/macrophages by a combination of immunocytochemistry and in situ hybridization

The expression of many cytokines is dysregulated in individuals infected with the human immunodeficiency virus-1 (HIV-1). To determine the effects of HIV-1 infection on cytokine expression in individual cells (at the single cell level), we investigated the intracellular levels of proinflammatory cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, and IL-8) and hematopoietic growth factors (granulocyte colony-stimulating factor [G-CSF], granulocyte-macrophage colony-stimulating factor [GM-CSF]) in monocyte-derived macrophages, mock-infected, or infected with HIV-1 by immunocytochemical staining for cytokine protein and compared this with secreted cytokine levels as determined by specific enzyme-linked immunosorbent assay (ELISA). No difference in the frequency or intensity of cell-associated immunocytochemical cytokine staining could be observed between HIV-1 and mock-infected cells even though the level of secreted proinflammatory cytokines increased and the hematopoietic growth factors decreased in HIV-1-infected cultures. Furthermore, equal expression of cytokine mRNA was observed in all cells in the culture regardless of whether the cells were productively infected with HIV-1 as determined by double-labelling immunocytochemical staining for HIV-1 p24 antigen and in situ hybridization for cytokine mRNA expression. These results indicate that HIV-1 infection results in dysregulation of intracellular cytokine mRNA expression and cytokine secretion not only in HIV-1-infected cells, but also through an indirect way(s) affecting cells not producing virus.     

Pectoralis major rupture during gait training: case report

The macrophage derived cytokines interleukin-beta (IL-1beta), and tumor necrosis factor alpha (TNFalpha), and the T-cell derived cytokine interferon gamma (IFNgamma) have been implicated to play an important role in early attack on islet cells during human islet transplantation (ITx). Therefore, the aim of this study was to investigate the influence of the current immunosuppressive induction therapy in clinical islet transplantation on mRNA expression of these cytokines in blood cells, compared to lipopolysaccharide (LPS) induced cytokine release in vitro and to plasma levels. The cytokine release correlated to lymphocyte counts and significantly decreased after ATG, and partially recovered 2 weeks after ITx. Unexpectedly, there was no correlation between mRNA expression for IL-1beta in total blood and the number of lymphocytes and monocytes remaining after anti thymocyte globulin (ATG)-therapy. Even when the blood was nearly totally depleted from mononuclear cells, high amounts of IL-1beta mRNA could be detected. However, IL-1beta secretion could not be stimulated in vitro. Our results show that application of ATG during ITx might contribute to graft survival during the early posttransplant period by suppression of the synthesis of monocyte derived cytokines IL-1beta and TNFalpha.     

Cell-associated human retinal pigment epithelium interleukin-8 and monocyte chemotactic protein-1: immunochemical and in-situ hybridization analyses

Human retinal pigment epithelial (RPE) cells secrete chemokines, interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) in response to pro-inflammatory cytokines. In this study we (1) examined the efficiency of human RPE IL-8 and MCP-1 secretion, (2) determined the amount of neutrophil and monocyte chemotactic activity in human RPE cell conditioned media and cell extracts that is attributable to IL-8 and MCP-1, respectively, and (3) assessed the sensitivity of immunohistochemistry and in situ hybridization for detecting chemokine production by cytokine-stimulated human RPE cells. Conditioned media and extracts from human RPE cells stimulated with various physiologic concentrations of interleukin-1 beta (IL-1 beta) (0.2-20 ng ml-1), tumor necrosis factor (TNF-alpha) (0.2-20 ng ml-1) or interferon-gamma (IFN-gamma) (10-1000 U ml-1) were examined to compare secreted and cell associated levels of IL-8 and MCP-1 at various time points up to 24 hr. ELISA demonstrated that IL-8 and MCP-1 are both efficiently secreted by pro-inflammatory cytokine treated human RPE cells. Substantial dose- and time-dependent RPE secretion of IL-8 was observed following stimulation with IL-1 beta or TNF-alpha, but cell associated IL-8 was detectable only after high dose (20 ng ml-1) IL-1 beta stimulation and comprised less than 1% of the total IL-8 induced. Dose- and time-dependent RPE cell MCP-1 secretion was also observed following IL-1 beta > TNF-alpha > IFN-gamma stimulation, with an average of 4% of the total MCP-1 retained within RPE. Bioassays demonstrated neutrophil and monocyte chemotactic activity in conditioned media from stimulated RPE cells, but not in human RPE cell extracts. Inhibition of conditioned media-induced chemotaxis by specific anti-IL-8 or anti-MCP-1 antibodies demonstrated that IL-8 and MCP-1 were responsible for the majority of HRPE-derived neutrophil (> 60%) and monocyte (53-57%) chemotactic activity, respectively. Using in situ hybridization IL-8 mRNA was readily detected within IL-1 beta > TNF-alpha stimulated RPE cells and MCP-1 mRNA easily visualized within IL-1 beta > TNF-alpha > or IFN-gamma stimulated cells. Immunohistochemistry to detect IL-8 was positive only in RPE cells exposed to high dose IL-1 beta (20 ng ml-1) for 8 or 24 hr and was weak. Immunohistochemical staining for MCP-1 in RPE cells was more intense and was visualized within RPE cells stimulated with IL-beta, TNF-alpha, or IFN-gamma. This study demonstrates that: (1) RPE cells efficiently secrete IL-8 and MCP-1 upon stimulation with pro-inflammatory cytokines; (2) secreted IL-8 and MCP-1 account for the majority of human RPE neutrophil and monocyte chemotactic activity; (3) in situ hybridization readily detects IL-8 and MCP-1 mRNA in cytokine stimulated RPE cells; and (4) immunohistochemistry demonstrates cell-associated MCP-1 in cytokine stimulated RPE cells, but only minimal cell-associated IL-8.     

Patterns of cytokine production in psoriatic synovium

OBJECTIVE: To determine patterns of cytokine production and mRNA expression in synovium from patients with psoriatic arthritis (PsA) and to compare the profile of cytokine production in PsA explants with those derived from rheumatoid (RA) and osteoarthritic (OA) synovia and psoriatic skin. METHODS: Cytokine levels were measured in supernatants from synovial and dermal explant cultures at Day 10 by ELISA. Cytokine mRNA expression in PsA whole tissue was determined by multi-gene assay. Cytokine levels in explant supernatants were compared between PsA, RA and OA, and psoriatic skin. Synovial tissues were scored histologically by a pathologist blinded to the clinical diagnosis. RESULTS: PsA explants released elevated levels of interleukin (IL)-1beta, IL-2, IL-10, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha, but not IL-4 or IL-5. A similar pattern of gene expression was detected in whole synovial tissue. These cytokine levels were greater in PsA than RA, despite higher histopathologic scores in RA explants. Production of IL-1beta, IFN-gamma, and IL-10 were strongly correlated. Levels of IFN-gamma, IL-1beta, and IL-10 were higher in psoriatic synovium than psoriatic dermal plaques. CONCLUSION: The cytokine profile in PsA is characterized by the presence of Th1 cytokines and the monokines TNF-alpha and IL-1beta and very elevated levels of IL-10. The higher levels of these cytokines in PsA compared to RA suggest the presence of different underlying mechanisms.