Elevation of proinflammatory cytokine (IL-18, IL-17, IL-12) and Th2 cytokine (IL-4) concentrations in patients with systemic lupus erythematosus

Platelet-activating factor induces Th17 cell differentiation

Th17 cells have been implicated in a number of inflammatory and autoimmune diseases. The phospholipid mediator platelet-activating factor (PAF) is found in increased concentrations in inflammatory lesions and has been shown to induce IL-6 production. We investigated whether PAF could affect the development of Th17 cells. Picomolar concentrations of PAF induced IL-23, IL-6, and IL-1β expression in monocyte-derived Langerhans cells (LCs) and in keratinocytes. Moreover, when LC were pretreated with PAF and then cocultured with anti-CD3- and anti-CD28-activated T cells, the latter developed a Th17 phenotype, with a significant increase in the expression of the transcriptional regulator RORγt and enhanced expression of IL-17, IL-21, and IL-22. PAF-induced Th17 development was prevented by the PAF receptor antagonist WEB2086 and by neutralizing antibodies to IL-23 and IL-6R. This may constitute a previously unknown stimulus for the development and persistence of inflammatory processes that could be amenable to pharmacologic intervention.

The dysregulation of cytokine networks in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with chronic immune activation and tissue damage. Organ damage in SLE results from the deposition of immune complexes and the infiltration of activated T cells into susceptible organs. Cytokines are intimately involved in every step of the SLE pathogenesis. Defective immune regulation and uncontrolled lymphocyte activation, as well as increased antigen presenting cell maturation are all influenced by cytokines. Moreover, expansion of local immune responses as well as tissue infiltration by pathogenic cells is instigated by cytokines. In this review, we describe the main cytokine abnormalities reported in SLE and discuss the mechanisms that drive their aberrant production as well as the pathogenic pathways that their presence promotes.

B cell signature during inactive systemic lupus is heterogeneous: toward a biological dissection of lupus

Systemic lupus erythematosous (SLE) is an autoimmune disease with an important clinical and biological heterogeneity. B lymphocytes appear central to the development of SLE which is characterized by the production of a large variety of autoantibodies and hypergammaglobulinemia. In mice, immature B cells from spontaneous lupus prone animals are able to produce autoantibodies when transferred into immunodeficient mice, strongly suggesting the existence of intrinsic B cell defects during lupus. In order to approach these defects in humans, we compared the peripheral B cell transcriptomas of quiescent lupus patients to normal B cell transcriptomas. When the statistical analysis is performed on the entire group of patients, the differences between patients and controls appear quite weak with only 14 mRNA genes having a false discovery rate ranging between 11 and 17%, with 6 underexpressed genes (PMEPA1, TLR10, TRAF3IP2, LDOC1L, CD1C and EGR1). However, unforced hierarchical clustering of the microarrays reveals a subgroup of lupus patients distinct from both the controls and the other lupus patients. This subgroup has no detectable clinical or immunological phenotypic peculiarity compared to the other patients, but is characterized by 1/an IL-4 signature and 2/the abnormal expression of a large set of genes with an extremely low false discovery rate, mainly pointing to the biological function of the endoplasmic reticulum, and more precisely to genes implicated in the Unfolded Protein Response, suggesting that B cells entered an incomplete BLIMP1 dependent plasmacytic differentiation which was undetectable by immunophenotyping. Thus, this microarray analysis of B cells during quiescent lupus suggests that, despite a similar lupus phenotype, different biological roads can lead to human lupus.

4-1BB triggering ameliorates experimental autoimmune encephalomyelitis by modulating the balance between Th17 and regulatory T cells

Agonistic anti-4-1BB Ab is known to ameliorate experimental autoimmune encephalomyelitis. 4-1BB triggering typically leads to the expansion of CD8(+) T cells, which produce abundant IFN-γ, and this in turn results in IDO-dependent suppression of autoimmune responses. However, because neutralization of IFN-γ or depletion of CD8(+) T cell only partially abrogates the effect of 4-1BB triggering, we sought to identify an additional mechanism of 4-1BB-triggered suppression of autoimmune responses using IFN-γ- or IFN-γR-deficient mice. 4-1BB triggering inhibited the generation of Th17 cells that is responsible for experimental autoimmune encephalomyelitis induction and progression, and increased Foxp3(+)CD4(+) regulatory T (Treg) cells, particularly among CD4(+) T cells. This was not due to a direct effect of 4-1BB signaling on CD4(+) T cell differentiation: 4-1BB signaling not only reduced Th17 cells and increased Treg cells in wild-type mice, which could be due to IFN-γ production by the CD8(+) T cells, but also did so in IFN-γ-deficient mice, in that case by downregulating IL-6 production. These results show that although secondary suppressive mechanisms evoked by 4-1BB triggering are usually masked by the strong effects of IFN-γ, 4-1BB signaling seems to modulate autoimmune responses by a number of mechanisms, and modulation of the Th17 versus Treg cell balance is one of those mechanisms.

Cholera toxin B subunit linked to glutamic acid decarboxylase suppresses dendritic cell maturation and function

Dendritic cells are the largest population of antigen presenting cells in the body. One of their main functions is to regulate the delicate balance between immunity and tolerance responsible for maintenance of immunological homeostasis. Disruption of this delicate balance often results in chronic inflammation responsible for initiation of organ specific autoimmune diseases such as rheumatoid arthritis, multiple sclerosis and type I diabetes. The cholera toxin B subunit (CTB) is a weak mucosal adjuvant known for its ability to stimulate immunity to antigenic proteins. However, conjugation of CTB to many autoantigens can induce immunological tolerance resulting in suppression of autoimmunity. In this study, we examined whether linkage of CTB to a 5kDa C-terminal protein fragment of the major diabetes autoantigen glutamic acid decarboxylase (GAD(35)), can block dendritic cell (DC) functions such as biosynthesis of co-stimulatory factor proteins CD86, CD83, CD80 and CD40 and secretion of inflammatory cytokines. The results of human umbilical cord blood monocyte-derived DC-GAD(35) autoantigen incubation experiments showed that inoculation of immature DCs (iDCs), with CTB-GAD(35) protein dramatically suppressed levels of CD86, CD83, CD80 and CD40 co-stimulatory factor protein biosynthesis in comparison with GAD(35) alone inoculated iDCs. Surprisingly, incubation of iDCs in the presence of the CTB-autoantigen and the strong immunostimulatory molecules PMA and Ionomycin revealed that CTB-GAD(35) was capable of arresting PMA+Ionomycin induced DC maturation. Consistent with this finding, CTB-GAD(35) mediated suppression of DC maturation was accompanied by a dramatic decrease in the secretion of the pro-inflammatory cytokines IL-12/23p40 and IL-6 and a significant increase in secretion of the immunosuppressive cytokine IL-10. Taken together, our experimental data suggest that linkage of the weak adjuvant CTB to the dominant type 1 diabetes autoantigen GAD strongly inhibits DC maturation through the down regulation of major co-stimulatory factors and inflammatory cytokine biosynthesis. These results emphasize the possibility that CTB-autoantigen fusion proteins enhance DC priming of naïve Th0 cell development in the direction of immunosuppressive T lymphocytes. The immunological phenomena observed here establish a basis for improvement of adjuvant augmented multi-component subunit vaccine strategies capable of complete suppression of organ-specific autoimmune diseases in vivo.

Bee venom-associated Th1/Th2 immunoglobulin class switching results in immune tolerance of NZB/W F1 murine lupus nephritis

BACKGROUND/AIMS

Bee venom (BV) therapy has been used to treat inflammatory diseases including rheumatoid arthritis in humans and in experimental animals. This study was conducted to examine the therapeutic effect of BV on established lupus nephritis in New Zealand Black/White (NZB/W) F1 female mice.

METHODS

Beginning at 18 weeks of age, mice were given a subcutaneous injection of either BV (3 mg/kg BW) or an equal volume of saline once a week until the end of the study. To examine the effect of BV on CD4+CD25+Foxp3+ regulatory T cells, splenocytes from NZB/W mice (23 weeks of age) were treated with BV (1 μg/ml) or PBS in the presence of anti-CD3ε (1 μg/ml) and anti-CD28 antibodies (4 μg/ml) for 48 h.

RESULTS

BV administration delayed the development of proteinuria to a significant extent, prevented renal inflammation, reduced tubular damage, and reduced immune deposits in the glomeruli. Interestingly, CD4+CD25+ regulatory T cells were significantly increased in vitro and in vivo after BV treatment.

CONCLUSION

Collectively, the administration of BV that has immune modulating effects represents an applicable treatment of lupus nephritis in NZB/W F1 mice.

Interferon-lambda1 induces peripheral blood mononuclear cell-derived chemokines secretion in patients with systemic lupus erythematosus: its correlation with disease activity

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organ systems. Previous studies have suggested that interferon-lambda 1 (IFN-λ1), a type III interferon, plays an immunomodulatory role. In this study we investigated its role in SLE, including its correlation with disease activity, organ disorder and production of chemokines.

METHODS

We determined levels of IFN-λ1 mRNA in peripheral blood mononuclear cells (PBMC) and serum protein levels in patients with SLE using real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunoassay (ELISA). Further, we detected the concentration of IFN-inducible protein-10 (IP-10), monokine induced by IFN-γ (MIG) and interleukin-8 (IL-8) secreted by PBMC under the stimulation of IFN-λ1 using ELISA.

RESULTS

IFN-λ1 mRNA and serum protein levels were higher in patients with SLE compared with healthy controls. Patients with active disease showed higher IFN-λ1 mRNA and serum protein levels compared with those with inactive disease as well. Serum IFN-λ1 levels were positively correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), anti-dsDNA antibody, C-reactive protein (CRP) and negatively correlated with complement 3. Serum IFN-λ1 levels were higher in SLE patients with renal involvement and arthritis compared with patients without the above-mentioned manifestations. IFN-λ1 with different concentrations displayed different effects on the secretion of the chemokines IP-10, MIG and IL-8.

CONCLUSIONS

These findings indicate that IFN-λ1 is probably involved in the renal disorder and arthritis progression of SLE and associated with disease activity. Moreover, it probably plays an important role in the pathogenesis of SLE by stimulating secretion of the chemokines IP-10, MIG and IL-8. Thus, IFN-λ1 may provide a novel research target for the pathogenesis and therapy of SLE.

Distribution of Th17 cells and Th1 cells in peripheral blood and cerebrospinal fluid in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated demyelinating disease of the peripheral nervous system. Th17 and Th1 cells contribute to the pathogenesis of most autoimmune diseases, but little is known about their distribution and reciprocal relationship in CIDP. In this study, we analyzed the distribution of Th17, Th1, and Th17/Th1 cells in the peripheral blood and cerebrospinal fluid (CSF). The results showed that the frequency of Th17 cells was significantly higher in the peripheral blood mononuclear cell (PBMCs) and CSF of active CIDP in comparison with remitting CIDP or to other non-inflammatory neurological diseases (ONDs), accompanied by similar findings for Th17/Th1 cells. Both active and remitting CIDP have higher percentage of Th1 cells in the CSF than OND. CSF protein levels positively correlated with the frequencies of Th17 cells either in the PBMCs or CSF of active CIDP, while there was no significant correlation with Th1 cells. In line with these observations, the levels of interleukin-17 (IL-17) in plasma and transcript factors retinoic acid receptor-related orphan receptor (ROR)γt expressed by PBMCs were significantly higher in the active CIDP than remitting CIDP or OND. In summary, our preliminary findings suggest that elevated numbers of inflammatory T cells, especially for Th17 cells, might be an important determinant in the evolution of CIDP.

IL-17-producing T cells in lupus nephritis

Significant evidence implicates interleukin-17 (IL-17) in the pathogenesis of systemic lupus erythematosus (SLE), particularly in the development of tissue damage. IL-17 production and IL-17-producing CD4+ and CD3 + CD4-CD8- cells are increased in patients with SLE. IL-17-producing cells are present in the inflamed kidney tissues from patients with lupus nephritis. In lupus-prone mice, IL-17 production appears to be involved in the expression of disease pathology and pharmacologic or genetic manipulation of its production results in suppression of the disease. It becomes obvious that the use of biologics including humanized anti-IL-17 antibodies or decoy IL-17 receptors deserve clinical consideration. Similarly, the development of drugs that suppress the production of IL-17 is in order.

Impact of interleukin-17 on macrophage phagocytosis of apoptotic neutrophils and particles

There is now substantial evidence that the cytokine interleukin-17 orchestrates the accumulation of neutrophils in mammals and thereby contributes to host defense. However, the role of IL-17 in controlling neutrophil turnover is not fully understood. Here, we demonstrate that IL-17 stimulates the apoptosis of mouse neutrophils and, simultaneously, the release of the microbicidal compound, myeloperoxidase. IL-17 also stimulates mouse macrophages to phagocytose aged neutrophils and latex beads, and it induces an increase in a soluble form of the phagocytic receptor, lectin-like oxidized low-density lipoprotein receptor-1 as well. In contrast, IL-17 does not markedly increase the release of the archetype neutrophil-recruiting cytokine, macrophage inflammatory protein-2 in mouse macrophages. Importantly, IL-17 also stimulates the phagocytosis of latex beads in human monocyte-derived macrophages. Thus, IL-17 bears the potential to control both phagocytosis and neutrophil turnover during activation of host defense.

Interleukin-17 contributes to the pathogenesis of autoimmune hepatitis through inducing hepatic interleukin-6 expression

T helper cells that produce IL-17 (Th17 cells) have recently been identified as the third distinct subset of effector T cells. Emerging data suggests that Th17 cells play an important role in the pathogenesis of many liver diseases by regulating innate immunity, adaptive immunity, and autoimmunity. In this study, we examine the role and mechanism of Th17 cells in the pathogenesis of autoimmune hepatitis (AIH). The serum levels of IL-17 and IL-23, as well as the frequency of IL-17+ cells in the liver, were significantly elevated in patients with AIH, compared to other chronic hepatitis and healthy controls. The hepatic expressions of IL-17, IL-23, ROR-γt, IL-6 and IL-1β in patients with AIH were also significantly increased and were associated with increased inflammation and fibrosis. IL-17 induces IL-6 expression via the MAPK signaling pathway in hepatocytes, which, in turn, may further stimulate Th17 cells and forms a positive feedback loop. In conclusion, Th17 cells are key effector T cells that regulate the pathogenesis of AIH, via induction of MAPK dependent hepatic IL-6 expression. Blocking the signaling pathway and interrupting the positive feedback loop are potential therapeutic targets for autoimmune hepatitis.

Recovery of the immune balance between Th17 and regulatory T cells as a treatment for systemic lupus erythematosus

The Th17 lineage, a lineage of effector CD4(+) T cells, is characterized by the production of IL-17. Expansion of Th17 cells has been implicated in a growing list of autoimmune disorders. Our studies, as well as others, have shown that Th17 cells play a key role in the pathogenesis of SLE. Therefore, some investigators advocate that Th17 cells are a promising therapeutic target for SLE. However, neutralization of IL-17 in vivo actually aggravated inflammation by inducing infiltration of other effector cells. Thus, the therapeutic effects of antagonizing Th17 cells for the treatment of SLE in the clinic are worth discussing. Moreover, in patients with SLE, the expansion of effector T cells is always closely related to the depletion and dysfunction of Treg cells. Therefore, we hypothesize that for the treatment of SLE, we should focus on therapeutic agents that can regulate the immune balance between Th17 and Treg cells rather than on those that exclusively regulate Th17 cells.

C1q regulation of dendritic cell development from monocytes with distinct cytokine production and T cell stimulation

The causative association of complement C1q deficiency with systemic lupus erythematosus (SLE), which inevitably involves the breakdown of tolerance, remains poorly explained. Its non-hepatic, macrophage and dendritic cell (DC) origin may be highly relevant. In tissues, C1q is produced by DCs and macrophages which deposits around these cells and we ask whether this pericellular form of C1q regulates DC development from monocytes. DCs cultured on immobilized C1q (C1q-DCs) show similar MHC, CD40, CD80, CD86, CD83 and CCR7 expression as normal DCs, but these cells exhibit increased phagocytosis of apoptotic cells and elevated IL-10 but reduced IL-12 and IL-23 production. Intracellularly, C1q-DCs exhibit increased ERK, p38 and p70S6 kinase activity. By mixed leukocyte reaction, C1q-DCs show reduced Th1 and Th17 induction from allogeneic CD4(+) T cells. LPS and IFNγ, which cause normal DCs to induce increased CD25 expression on CD4(+) T cells, attenuate C1q-DC induction of CD25. These imply that the DC pericellular C1q may induce tolerogenic properties in developing DCs.

The emergence of TH17 cells as effectors of renal injury

IL-17-producing Th17 effector cells directly induce renal inflammation by activating neutrophils or by participating in macrophage-mediated tissue injury. Th17 cells and cytokines participate in human and experimental renal disease, especially in proliferative glomerulonephritis where Th17 effector cells are active. Although growing evidence suggests Th17 cells are particularly relevant to effector responses involving neutrophils, there are still important questions to address before the complete functions of Th17 cells in renal disease are understood fully.

Identification of Baicalin as an immunoregulatory compound by controlling T(H)17 cell differentiation

T_H17 cells have been implicated in a growing list of inflammatory disorders. Antagonism of T_H17 cells can be used for the treatment of inflammatory injury. Currently, very little is known about the natural compound controlling the differentiation of T_H17 cells. Here, we showed that Baicalin, a compound isolated from a Chinese herb, inhibited T_H17 cell differentiation both in vitro and in vivo. Baicalin might inhibit newly generated T_H17 cells via reducing RORγt expression, and together with up-regulating Foxp3 expression to suppress RORγt-mediated IL-17 expression in established T_H17 cells. In vivo treatment with Baicalin could inhibit T_H17 cell differentiation, restrain T_H17 cells infiltration into kidney, and protect MRL/lpr mice against nephritis. Our findings not only demonstrate that Baicalin could control T_H17 cell differentiation but also suggest that Baicalin might be a promising therapeutic agent for the treatment of T_H17 cells-mediated inflammatory diseases.

Role of TH-17 cells in rheumatic and other autoimmune diseases

In humans multiple pathways can induce TH-17 cell differentiation, whereas in mice this process is mostly modulated by IL-6 and TGF-β. IL-17 produced by TH-17 cells has been associated with a number of inflammatory autoimmune diseases including psoriasis, systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis, and rheumatoid arthritis. In this review, we have primarily focused on the role of TH-17 cells/IL-17 in the pathogenesis of rheumatoid arthritis and experimental arthritis. The potential role of TH-17 cells in rheumatoid arthritis progression has been demonstrated by correlating the percent TH-17 cells or levels of IL-17 with rheumatoid arthritis disease activity score and C-reactive protein levels. Further, previous studies suggest that IL-17 mediated vascularization may lay the foundation for rheumatoid arthritis joint neutrophil and monocyte recruitment as well as cartilage and bone destruction. The profound role of IL-17 in the pathogenesis of experimental arthritis may be due to its synergistic effect with TNF-α and IL-1β. Although the initial clinical trial employing anti-IL-17 antibody has been promising for rheumatoid arthritis, future studies in humans will shed more light on how anti-IL-17 therapy affects rheumatoid arthritis and other autoimmune disease pathogenesis.

Current and emerging strategies for the treatment and management of systemic lupus erythematosus based on molecular signatures of acute and chronic inflammation

Lupus is a chronic, systemic inflammatory condition in which eicosanoids, cytokines, nitric oxide (NO), a deranged immune system, and genetics play a significant role. Our studies revealed that an imbalance in the pro- and antioxidants and NO and an alteration in the metabolism of essential fatty acids exist in lupus. The current strategy of management includes administration of nonsteroidal anti-inflammatory drugs such as hydroxychloroquine and immunosuppressive drugs such as corticosteroids. Investigational drugs include the following: 1) belimumab, a fully human monoclonal antibody that specifically recognizes and inhibits the biological activity of B-lymphocyte stimulator, also known as B-cell-activation factor of the TNF family; 2) stem cell transplantation; 3) rituximab, a chimeric monoclonal antibody against CD20, which is primarily found on the surface of B-cells and can therefore destroy B-cells; and 4) IL-27, which has potent anti-inflammatory actions. Our studies showed that a regimen of corticosteroids and cyclophosphamide, and methods designed to enhance endothelial NO synthesis and augment antioxidant defenses, led to induction of long-lasting remission of the disease. These results suggest that methods designed to modulate molecular signatures of the disease process and suppress inflammation could be of significant benefit in lupus. Some of these strategies could be vagal nerve stimulation, glucose-insulin infusion, and administration of lipoxins, resolvins, protectins, and nitrolipids by themselves or their stable synthetic analogs that are known to suppress inflammation and help in the resolution and healing of the inflammation-induced damage. These strategies are likely to be useful not only in lupus but also in other conditions, such as rheumatoid arthritis, scleroderma, ischemia-reperfusion injury to the myocardium, ischemic heart disease, and sepsis.

Psoriasis: from pathogenesis to novel therapeutic approaches

Psoriasis is one of the commonest chronic inflammatory disorders. Its cause is unknown, but a wealth of studies indicate that the disease results from a complex and dynamic interplay between genetic and environmental factors that trigger an excessive inflammatory response in the skin. Dendritic cells and effector T-cells are central in the development of the psoriastic lesion, and cytokines produced by these cells stimulate keratinocytes to proliferate and increase the migration of inflammatory cells into the skin, promoting epidermal hyperplasia and inflammation. Understanding the immunology of the psoriatic plaque has led to new therapeutic options and novel candidates for immunomodulation, and has changed the ways psoriatic patients are managed.

Review: T helper 17 cells: their role in glomerulonephritis

T helper (Th) cells are an integral part of the host's immune response to eliminate invading pathogens. However, autoimmune or 'autoinflammatory' diseases can develop if Th cell responses are not effectively regulated. Several subsets of Th cells exist, including the Th17 subset that produces interleukin-17A, important in experimental models of organ-specific autoimmune inflammation. Its discovery has explained paradoxical observations in model systems thought to be Th1 mediated but were exacerbated in the absence of interferon-gamma, the prototypic Th1 effector cytokine. Th17 cells express unique transcription factors and secrete a unique pattern of cytokines. Interleukin-17A induces pro-inflammatory cytokines and chemokines and mediates neutrophil recruitment. Th17 cells have a reciprocal relationship with T regulatory cells and can also mediate suppression of Th1 responses. Recent studies also suggest that Th17 cells are not terminally differentiated but can switch into Th1 cells. Th17 cells have themselves been recently shown to induce antigen-specific cell-mediated proliferative glomerulonephritis. There is increasing evidence implicating Th17 cells in anti-glomerular basement membrane disease, lupus nephritis and pauci-immune glomerulonephritis. This review will review the discovery of the Th17 subset, its properties, its relationship with other Th subsets and assess the current evidence implicating Th17 cells in glomerulonephritis.

IL-6: regulator of Treg/Th17 balance

IL-6 is a pleiotropic cytokine involved in the physiology of virtually every organ system. Recent studies have demonstrated that IL-6 has a very important role in regulating the balance between IL-17-producing Th17 cells and regulatory T cells (Treg). The two T-cell subsets play prominent roles in immune functions: Th17 cell is a key player in the pathogenesis of autoimmune diseases and protection against bacterial infections, while Treg functions to restrain excessive effector T-cell responses. IL-6 induces the development of Th17 cells from naïve T cells together with TGF-beta; in contrast, IL-6 inhibits TGF-beta-induced Treg differentiation. Dysregulation or overproduction of IL-6 leads to autoimmune diseases such as multiple sclerosis (MS) and rheumatoid arthritis (RA), in which Th17 cells are considered to be the primary cause of pathology. Given the critical role of IL-6 in altering the balance between Treg and Th17 cells, controlling IL-6 activities is potentially an effective approach in the treatment of various autoimmune and inflammatory diseases. Here, we review the role of IL-6 in regulating Th17/Treg balance and describe the critical functions of IL-6 and Th17 in immunity and immune-pathology.

Potentiation of Th17 cytokines in aging process contributes to the development of colitis

Th17 cells, which produce IL-17 and IL-22, promote autoimmunity in mice and have been implicated in the pathogenesis of autoimmune/inflammatory diseases in humans. However, the Th17 immune response in the aging process is still not clear. In the present study, we found that the induction of IL-17-producing CD4(+) T cells was significantly increased in aged individuals compared with young healthy ones. The mRNA expression of IL-17, IL-17F, IL-22, and RORC2 was also significantly increased in aged people. Similar to humans, Th17 cells as well as mRNAs encoding IL-17, IL-22 and RORγt were dramatically elevated in naïve T cells from aged mouse compared to young ones. In addition, CD44 positive IL-17-producing CD4(+) T cells were significantly higher in aged mice, suggesting that memory T cells are an important source of IL-17 production. Furthermore, the percentage of IL-17-producing CD4(+) T cells generated in co-culture with dendritic cells from either aged or young mice did not show significant differences, suggesting that dendritic cells do not play a primary role in the elevation of Th17 cytokines in aged mouse cells. Importantly, transfer of CD4(+)CD45Rb(hi) cells from aged mice induced more severe colitis in RAG(-/-) mice compared to cells from young mice, Taken together, these results suggest that Th17 immune responses are elevated in aging humans and mice and may contribute to the increased development of inflammatory disorders in the elderly.

Elevated interleukin-18 and skewed Th1:Th2 immune response in lupus nephritis

There is evidence that interleukin-18 plays a role in lupus nephritis (LN). Since interleukin -18 (IL-18) promotes polarization of the immune response toward Th1, we investigated level of IL-18 and assessed the phenotypic distribution of Th1 and Th2 type cells in LN. A predominance of Th1 type (IFN-γ+) cells and significant correlations with serum IL-18 was seen in the patients with LN compared to healthy controls. Although most patients were treated with high dosage of glucocorticoid and other immunosuppressive agents, higher level of IL-18 was found in both serum and glomeruli. However, there was no paralleled upregulation of its gene expression in peripheral blood mononuclear cells. Our findings indicate that the elevated IL-18 should be a symbol of disease activity and play a major role in the pathogenesis of LN by promoting cytokine imbalance towards Th1 type immune response. We conclude that patients with LN would benefit from it while the bioactivity of this cytokine was effectively counteracted.

Th17 cell dynamics in HIV infection

PURPOSE OF REVIEW

Th17 cells are a newly identified subtype of CD4 T cells that respond to bacterial and fungal antigens and are important in mucosal immunology. Because HIV infection results in loss of CD4 T cells as well as disruption to the gastrointestinal tract that causes microbial translocation and immune activation, Th17 cells potentially play an important role in HIV pathogenesis. Here we examine the relationship between Th17 cells and HIV disease pathogenesis.

RECENT FINDINGS

Th17 cells are preferentially lost from the gastrointestinal tract of HIV-infected individuals, which is not entirely due to direct infection, as Th17 cells can be infected in vivo, but are not preferentially infected. Long-term highly active antiretroviral therapy (HAART) can result in restoration of Th17 cells in the gastrointestinal, which may be associated with better disease prognosis. Furthermore, other cells, such as Vdelta1 T cells, can make IL-17 in vivo during HIV infection and may contribute to antibacterial immunity after loss of Th17 cells.

SUMMARY

Recent studies have improved our understanding of the role for Th17 cells during HIV infection; however, more studies are needed to discern better the detrimental consequences of loss of Th17 cells during HIV infection.

Interleukin 4 and STAT6 gene polymorphisms are associated with systemic lupus erythematosus in Chinese patients

An imbalance between T Helper 1 (TH1) and T Helper 2 (TH2) cytokine production is important for the pathogenesis of systemic lupus erythematosus (SLE). We aimed to investigate gene—gene associations of TH1 and TH2 cytokines genes in Chinese patients with SLE. Twenty single nucleotide polymorphisms (SNPs) in eight cytokines genes were genotyped in 110 SLE patients and 138 healthy controls in a case—control association study. The minor allelic frequencies of interleukin4(IL4) -590 T/C, -33 T/C, 9241C/G, and IL10 -592 A/C were significantly increased in SLE patients compared with those in controls (p < 0.05). None of the separate 20 SNPs showed significant association with SLE after Bonferroni correction. An IL4 haplotype -590C/-33C/9241G/14965C was significantly associated with SLE (odds ratio 3.7, 95% confidence interval [CI] 1.5—8.9, p = 0.004, Bonferroni-corrected p = 0.024). A borderline significant three-locus gene—gene interaction among IL4 9241 C/G, IL4 -33 T/C, signal transducer and activator of transcription 6, IL4-induced (STAT6) 2892 C/T was detected by a multifactor dimensionality reduction test (p = 0.051). However, the presence of two at-risk genotypes lead to increased risk of SLE for two-locus interaction using logistic regression method. The risk of SLE increased significantly when a subject has two at-risk genotypes for IL4 -590C and STAT6 2892C (odds ratio, 3.24, 95% CI 1.5—7.0, p = 0.003, Bonferroni-corrected p = 0.009), IL4 -33C and STAT6 2892C (odds ratio 3.06, 95% CI 1.4— 6.7, p = 0.005, Bonferroni-corrected p = 0.015), as well as IL4 9241G and STAT6 2892C (odds ratio 3.34, 95% CI 1.6—7.1, p = 0.002, Bonferroni-corrected p = 0.006). Further, plasma IL-4 concentrations were significantly lower in SLE patients than in healthy controls (1.59 + 3.53 versus 5.67 + 11.28 pg/ml, p = 0.042). These results indicated that IL4 and STAT6 genes might be involved in the etiology of SLE and potentially increased SLE risk through their interaction effect in Chinese patients.

Therapeutic effects of umbilical cord blood-derived mesenchymal stem cell transplantation in experimental lupus nephritis

Mesenchymal stem cells (MSCs) have been shown to possess immunomodulatory properties. Systemic lupus erythematosus is an autoimmune disease that results in nephritis and subsequent destruction of renal microstructure. We investigated whether transplantation of human umbilical cord blood-derived MSCs (uMSCs) is useful in alleviating lupus nephritis in a murine model. It was found that uMSCs transplantation significantly delayed the development of proteinuria, decreased anti-dsDNA, alleviated renal injury, and prolonged the life span. There was a trend of decreasing T-helper (Th) 1 cytokines (IFN-γ, IL-2) and proinflammatory cytokines (TNF-α, IL-6, IL-12) and increasing Th2 cytokines (IL-4, IL-10). The in vitro coculture experiments showed that uMSCs only inhibited lymphocytes and splenocytes proliferation but not mesangial cells. Long-term engraftment of uMSCs in the kidney was not observed either. Together, these findings indicated that uMSCs were effective in decreasing renal inflammation and alleviating experimental lupus nephritis by inhibiting lymphocytes, inducing polarization of Th2 cytokines, and inhibition of proinflammatory cytokines production rather than direct engraftment and differentiating into renal tissue. Therapeutic effects demonstrated in this preclinical study support further exploration of the possibility to use uMSCs from mismatched donors in lupus nephritis treatment.

IL-17 contributes to autoimmune hepatitis

The role of interleukin-17 (IL-17) in autoimmune hepatitis (AIH) was investigated. A mouse model of experimental autoimmune hepatitis was established, and the syngeneic S-100 antigen emulsified in complete Freud's adjuvant was injected intraperitoneally into adult male C57BL/6 mice. The IL-17 expression in serum and the livers of the mice models was detected by using ELISA and immunohistochemistry, respectively. IL-17 neutralizing antibody was used to study the biological effect of IL-17 in the experimental AIH. IL-17 neutralizing antibody in vivo administration alleviated the hepatic inflammation and ALT level in the AIH model. IL-17 in the peripheral blood mononuclear cells (PBMC) of AIH patients was measured by using real-time PCR method. The results showed that IL-17 level was significantly up-regulated in AIH patients and mice models. It was concluded that IL-17 contributed to the development of AIH and might be a potential therapeutic target of AIH.

Therapeutic potential of IL-27 in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by a diverse array of autoantibody production, complement activation and immune complex deposition, causing tissue and organ damage. Effective medical treatment for SLE is lacking because the etiology and pathogenesis of SLE are incompletely understood. It has been confirmed that cytokine-mediated immunity plays a crucial role in the pathogenesis of various autoimmune diseases including SLE. Recently, IL-27 was identified, which belongs to the IL-12 cytokine family. IL-27 exerts profound anti-inflammatory effects in several experimental autoimmune models. In particular, suppressive effects on T(H)17 cells, which are implicated in the pathogenesis of SLE. Moreover, administration of IL-27 or augmentation of IL-27 signaling suppresses some autoimmune diseases, including autoimmune diabetes and murine lupus, suggesting that IL-27 may be therapeutically relevant in SLE. In this article, we discuss the biological features of IL-27 and summarize recent advances on the role of IL-27 in the pathogenesis and treatment of SLE. Even though IL-27 has shown therapeutic potential in SLE, further research, particularly in humans, is needed in order to establish the precise role of IL-27 in SLE.

Differential immunotoxic effects of inorganic and organic mercury species in vitro

Despite the fact that humans are exposed to multiple forms of mercury (elemental, inorganic, and organic), most research on mercury toxicity has focused on methylmercury (MeHg) and on neurotoxic outcomes and mechanisms. Recent work has indicated that the immunotoxic effects of mercury compounds may be significant contributors to human disease as well as mechanistically relevant to other target organ toxicities. In this study, we compared the effects of inorganic Hg (iHg) to organic Hg species (MeHg and ethylmercury, EtHg) in human peripheral blood mononuclear cells (PBMCs) in vitro at sub-cytotoxic concentrations, using methods developed to characterize response of human PBMCs to iHg in vitro. PBMCs were isolated from six volunteer blood donors (three males and three females) and cultured in the presence and absence of lipopolysaccharide (LPS) and low levels (up to 200nM of each Hg species, separately) for 24h in culture. Cell culture supernatants were analyzed for cytokine concentrations with a bead-based multiplex assay. We report that iHg and MeHg both increase pro-inflammatory cytokine release in LPS-stimulated PBMCs, while EtHg decreases IFN-gamma release as well pro-inflammatory cytokine release. IL-17 release is significantly increased only in response to iHg treatment. Levels of anti-inflammatory cytokines (IL-1Ra and IL-10) were not significantly altered by any Hg treatment. These results indicate that both organic and inorganic species of Hg can affect the human immune system, but that they may exert different effects on immune function.

Cytokine-induced monocyte characteristics in SLE

Monocytes in SLE have been described as having aberrant behavior in a number of assays. We examined gene expression and used a genome-wide approach to study the posttranslational histone mark, H4 acetylation, to examine epigenetic changes in SLE monocytes. We compared SLE monocyte gene expression and H4 acetylation with three types of cytokine-treated monocytes to understand which cytokine effects predominated in SLE monocytes. We found that γ-interferon and α-interferon both replicated a broad range of the gene expression changes seen in SLE monocytes. H4 acetylation in SLE monocytes was overall higher than in controls and there was less correlation of H4ac with cytokine-treated cells than when gene expression was compared. A set of chemokine genes had downregulated expression and H4ac. Therefore, there are significant clusters of aberrantly expressed genes in SLE which are strongly associated with altered H4ac, suggesting that these cells have experienced durable changes to their epigenome.

Spontaneous autoimmune dacryoadenitis in aged CD25KO mice

To investigate time-related immunopathological changes in the lacrimal glands (LGs) of CD25KO mice, we examined LGs of C57BL/6 (wild-type) and CD25KO mice at 8, 12, and 16 weeks of age. T cell infiltration was quantified by flow cytometry, and gland function by tear peroxidase activity and epidermal growth factor mRNA expression. T helper (Th)-1, -2 and -17-associated cytokine expression was evaluated by real-time PCR. Epithelial apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay and activated caspase-3 staining. Eight-week-old CD25KO mice demonstrated significantly increased numbers of CD4 and CD8 T cells infiltrating the LGs. This peaked at 12 weeks of age. No peroxidase secretion was detected, and epidermal growth factor mRNA expression was barely detected in CD25KO mice. Ductal epithelial apoptosis was noted in CD25KO mice. Young CD25KO LGs had higher Th-17- (interleukin [IL]-23R, transforming growth factor-beta1, IL-17A, CC chemokine attractant ligand-20) and Th-1-associated cytokine transcripts (interferon-gamma, T-bet, IL-12, IL-2, IL-18) than young wild-type LGs. There was also a significant time-related decrease in IL-17A and CC chemokine attractant ligand-20 in CD25KO LGs. Taken together, autoimmune LG infiltration with loss of LG function was observed in CD25KO mice as early as 8 weeks of age. Time-related switch from Th-17 to Th-1 inflammation was noted in CD25KO mice.

The imbalance between regulatory and IL-17-secreting CD4+ T cells in lupus patients

It has been well recognized that a deficit of numbers and function of CD4+CD25+Foxp3+ cells (Treg) is attributed to the development of some autoimmune diseases; however, there are controversial data regarding the suppressive effect of Treg cells on the T cell response in systemic lupus erythematosus (SLE). Additionally, IL-17-producing cells (Th17) have been recently emerged as a new pathogenic cell, but their role in lupus remains unclear. In this study, we studied the connection between Treg and Th17 cells in lupus patients. We observed that, while Treg or Th17 cells alone were not correlated to SLE development, the ratio of Treg to Th17 cells in active SLE patients is significantly lower than that in inactive SLE patients and healthy controls, and we also found corticosteroid treatment increased the ratio of Treg to Th17 cells in active SLE patients. Moreover, this ratio is inversely correlated with the severity of active SLE. The present study indicates that active SLE appears to exist as an imbalance between Treg and Th17 cells. Correction of this Treg/Th17 imbalance may have therapeutic impact for patients with SLE.

(S)-armepavine from Chinese medicine improves experimental autoimmune crescentic glomerulonephritis

OBJECTIVE

Intra-renal T cells and macrophages play a key pathogenic role in the development and progression of glomerular crescents. We aimed to establish (S)-armepavine [(S)-ARM], a major bioactive compound of a Chinese medicinal plant, Nelumbo nucifera, as a potential therapeutic agent in the treatment of autoimmune crescentic glomerulonephritis (ACGN).

METHODS

A mouse ACGN model associated with T-cell dysregulation, was used to evaluate the therapeutic effects of (S)-ARM on the rapidly progressive glomerular disorder.

RESULTS

The results showed that (S)-ARM administered in the established phase of ACGN is capable of dramatically decreasing glomerular crescents in the kidney and improving proteinuria and renal dysfunction. These effects were associated with greatly inhibited infiltration of T cells/macrophages and suppressed nuclear factor (NF)-κB activation in the kidney, lowered serum levels of autoantibodies and both serum and intra-renal levels of pro-inflammatory cytokines, suppressed T/B-cell activation and T-cell proliferation of the spleen, reduced glomerular immune deposits and apoptosis in both the spleen and kidney in (S)-ARM-treated ACGN mice, compared with the vehicle-treated (disease control) group of ACGN mice.

CONCLUSION

We demonstrated therapeutic effects of (S)-ARM on ACGN as a result of: (i) early systemic negative modulation of T/B cells; (ii) intra-renal regulation of combined NF-κB activation and mononuclear leucocytic infiltration, thereby preventing glomerular crescent formation; and (iii) protection from apoptosis in both the spleen and kidney.

Foxp3+ regulatory T cells, Th17 effector cells, and cytokine environment in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is thought to result from an aberrant immune response. Inflammation in IBD may be caused by the loss of homeostasis between CD4+ CD25high Foxp3+ regulatory cells (Treg) and proinflammatory Th17 cells. The aim of this study was to investigate Treg and Th17 cells in the peripheral blood and intestinal mucosa of IBD patients and to assess the mucosal cytokine environment.

METHODS

Treg and Th17 cells were measured in peripheral blood of 63 IBD patients and 28 controls by flow cytometry. Forkhead box p3 (Foxp3), interleukin (IL)-17a, IL-1beta, IL-6, IL-21, IL-23, and transforming growth factor (TGF)-beta mRNA were analyzed using real-time reverse transcription polymerase chain reaction in intestinal biopsies of 24 IBD and 18 control subjects.

RESULTS

A decrease in Treg and increase in Th17 cells was observed in the peripheral blood of IBD patients. When measured in the same patient and expressed as a ratio, a significant decrease in Treg/Th17 ratio was observed in IBD. Elevated expression of Foxp3, IL-17a, IL-1beta, and IL-6 was observed in the mucosa of IBD patients, while TGF-beta was only elevated in ulcerative colitis.

CONCLUSION

IBD is associated with a reduced ratio of Treg to Th17 cells in peripheral blood and is characterized by a proinflammatory cytokine microenvironment, which supports the continued generation of Th17 cells.

Foxp3+ regulatory T cells, Th17 effector cells, and cytokine environment in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is thought to result from an aberrant immune response. Inflammation in IBD may be caused by the loss of homeostasis between CD4+ CD25high Foxp3+ regulatory cells (Treg) and proinflammatory Th17 cells. The aim of this study was to investigate Treg and Th17 cells in the peripheral blood and intestinal mucosa of IBD patients and to assess the mucosal cytokine environment.

METHODS

Treg and Th17 cells were measured in peripheral blood of 63 IBD patients and 28 controls by flow cytometry. Forkhead box p3 (Foxp3), interleukin (IL)-17a, IL-1beta, IL-6, IL-21, IL-23, and transforming growth factor (TGF)-beta mRNA were analyzed using real-time reverse transcription polymerase chain reaction in intestinal biopsies of 24 IBD and 18 control subjects.

RESULTS

A decrease in Treg and increase in Th17 cells was observed in the peripheral blood of IBD patients. When measured in the same patient and expressed as a ratio, a significant decrease in Treg/Th17 ratio was observed in IBD. Elevated expression of Foxp3, IL-17a, IL-1beta, and IL-6 was observed in the mucosa of IBD patients, while TGF-beta was only elevated in ulcerative colitis.

CONCLUSION

IBD is associated with a reduced ratio of Treg to Th17 cells in peripheral blood and is characterized by a proinflammatory cytokine microenvironment, which supports the continued generation of Th17 cells.

Th17 cells: the emerging reciprocal partner of regulatory T cells in the liver

T helper cells that produce interleukin-17 (IL-17) (Th17 cells) have recently been identified as the third distinct subset of effector T cells, the differentiation of which depends on specific transcription nuclear factor retinoic acid-related orphan nuclear receptor-gammat. Emerging data have suggested that Th17 cells play an important role in innate immunity, adaptive immunity and autoimmunity. Interestingly, there is a reciprocal relationship between Th17 cells and regulatory T cells (Treg), not only in development, but also in their effector function. Transforming growth factor (TGF)-beta induces Treg-specific transcription factor Forkhead box P3(FOXP3), while the addition of IL-6 to TGF-beta inhibits the generation of Treg cells and induces Th17 cells. It is proposed that the fine balance between Th17 and Treg cells is crucial for maintenance of immune homeostasis. In addition to IL-6, other factors such as retinoic acid, rapamycin, or cytokines (e.g., IL-2 and IL-27) could dictate the balance between Th17 and Treg cells. Since Treg cells play an important role in hepatic immunity with overregulation in chronic viral hepatitis and hepatic carcinoma, and inadequate inhibition in autoimmune liver diseases, graft rejection and acute liver failure, it is reasonable to assume that Th17 cells may play a reciprocal role in these diseases. Thus, future research on the Treg/Th17 balance may provide an opportunity to illustrate the pathogenesis of hepatic inflammation and to explore new therapeutic targets for immune-related liver diseases.

IL-17 in systemic lupus erythematosus

IL-17 is a cytokine with powerful proinflammatory activity. Production of IL-17 is abnormally increased in patients with systemic lupus erythematosus (SLE), a multiorgan chronic autoimmune disease. In patients with SLE, CD3⁺CD4⁻CD8⁻ (double negative) T cells are an important source of IL-17. IL-17 produced by double negative and CD4 T cells participates in the pathogenesis of the disease. IL-17-producing T cells are present in the kidneys of patients with lupus nephritis. IL-17 increased production in patients with SLE can amplify the immune response by increasing target organ inflammation and damage and by augmenting the production of antibodies by B cells.

Dysregulated balance of Th17 and Th1 cells in systemic lupus erythematosus

INTRODUCTION

Interleukin (IL)-17 is a proinflammatory cytokine that is produced largely by a unique CD4(+) T-helper (Th) subset called Th17 cells. The development of Th17 cells is suppressed by interferon (IFN)-gamma produced by Th1 cells, suggesting cross-regulation between Th17 and Th1 cells. Thus, this study analyzed the balance of CD4+ Th17 and Th1 cell responses in peripheral blood from patients with systemic lupus erythematosus (SLE) and healthy subjects.

METHODS

Twenty-five adult patients with SLE and 26 healthy subjects matched for gender and age (+/- 2 years) were recruited. Peripheral blood mononuclear cells (PBMCs) from patients and healthy subjects were stimulated for 4 h ex vivo with phorbol myristate acetate (PMA) and ionomycin. The frequency of CD4(+) T cells producing IL-17 and/or IFN-gamma was measured by using flow cytometry. Expression of Th17-associated chemokine receptors CCR4 and CCR6 on CD4(+) T cells as well as plasma levels of Th17-polarizing cytokines were assessed. Disease activity was evaluated by the SLE disease activity index score (SLEDAI). Unpaired t test and Pearson correlation were used for statistical analyses.

RESULTS

Patients with SLE had an increased frequency of CD4(+)IL-17(+) T cells compared with healthy subjects. However, the frequency of CD4(+)IFN-gamma(+) T cells was similar between the two groups, indicating an altered balance of Th17 and Th1 cell responses in SLE. Patients with SLE also had an increased frequency of CD4(+)CCR4(+)CCR6(+) T cells that are known to produce IL-17. The frequency of CD4(+)IL-17(+) T cells and CD4(+)CCR4(+)CCR6+ T cells correlated with disease activity. In measuring plasma levels of the Th17-polarizing cytokines, levels of IL-6 were higher in patients with SLE than in healthy subjects, although levels of IL-1beta, IL-21, IL-23, and transforming growth factor (TGF)-beta were not different between the two groups.

CONCLUSIONS

We demonstrate an enhanced Th17 cell response that correlates with disease activity in patients with SLE, suggesting a role for IL-17 in the pathogenesis of lupus. Our data indicate that the mechanisms involved in balancing Th1 and Th17 regulation, as well as in producing IL-6, are aberrant in SLE, leading to an increased Th17 response. We suggest that CCR4 and CCR6 expression on CD4(+) T cells should be considered as markers of disease activity, and that IL-17 blocking may offer a therapeutic target in SLE.

Th17 cytokines and arthritis

Th17 cells are implicated in human autoimmune diseases, such as rheumatoid arthritis (RA), although it has not been established whether this persistent destructive arthritis is driven by Th1 and/or Th17 cells. Interleukin-17A (IL-17A) contributes to the pathogenesis of arthritis as has been shown in several experimental arthritis models. Importantly, recent data from first clinical trials with anti-IL-17A antibody treatment in psoriatic arthritis patients and RA patients looks promising. This review summarizes the findings about the role of Th17 cells in arthritis and discusses the impact of the different Th17 cytokines in the pathogenesis of this disease. However, further studies are needed to unravel the interplay between IL-17A and other Th17 cytokines such as IL-17F, IL-22, and IL-21 in the pathoimmunological process of this crippling disease, in particular, whether regulating Th17 cell activity or specific combinations of Th17 cytokines will have additional value compared to neutralizing IL-17A activity alone. Moreover, tumor necrosis factor-positive Th17 cells are discussed as potential dangerous cells in driving persistent arthritis in human early RA.

Genome-wide association study in Asian populations identifies variants in ETS1 and WDFY4 associated with systemic lupus erythematosus

Systemic lupus erythematosus is a complex and potentially fatal autoimmune disease, characterized by autoantibody production and multi-organ damage. By a genome-wide association study (320 patients and 1,500 controls) and subsequent replication altogether involving a total of 3,300 Asian SLE patients from Hong Kong, Mainland China, and Thailand, as well as 4,200 ethnically and geographically matched controls, genetic variants in ETS1 and WDFY4 were found to be associated with SLE (ETS1: rs1128334, P = 2.33×10⁻¹¹, OR = 1.29; WDFY4: rs7097397, P = 8.15×10⁻¹², OR = 1.30). ETS1 encodes for a transcription factor known to be involved in a wide range of immune functions, including Th17 cell development and terminal differentiation of B lymphocytes. SNP rs1128334 is located in the 3′-UTR of ETS1, and allelic expression analysis from peripheral blood mononuclear cells showed significantly lower expression level from the risk allele. WDFY4 is a conserved protein with unknown function, but is predominantly expressed in primary and secondary immune tissues, and rs7097397 in WDFY4 changes an arginine residue to glutamine (R1816Q) in this protein. Our study also confirmed association of the HLA locus, STAT4, TNFSF4, BLK, BANK1, IRF5, and TNFAIP3 with SLE in Asians. These new genetic findings may help us to gain a better understanding of the disease and the functions of the genes involved.

In this study, we first conducted a genome-wide association study in a Hong Kong Chinese population, followed by replication in three other cohorts from Mainland China and a cohort from Thailand, which totaled 3,300 Asian patients and 4,200 ethnically and geographically matched controls. We identified novel variants in ETS1 and WDFY4 associated with SLE with genome-wide significance and confirmed the association of HLA locus, STAT4, BLK, IRF5, BANK1, TNFSF, and IRF5 with the disease. ETS1 encodes a critical transcription factor involved in Th17 and B cell development. Allelic expression study showed a significantly lower expression of ETS1 from the risk allele, which provided functional support to the genetic findings. WDFY4 is a huge protein with unknown function but is predominantly expressed in primary and secondary immune tissues, and a nonsynonymous SNP in this gene was found to be highly associated with SLE susceptibility. Our findings shed new light on the function of these genes as well as the mechanism of this devastating disease.

Th17 cytokines and arthritis

Th17 cells are implicated in human autoimmune diseases, such as rheumatoid arthritis (RA), although it has not been established whether this persistent destructive arthritis is driven by Th1 and/or Th17 cells. Interleukin-17A (IL-17A) contributes to the pathogenesis of arthritis as has been shown in several experimental arthritis models. Importantly, recent data from first clinical trials with anti-IL-17A antibody treatment in psoriatic arthritis patients and RA patients looks promising. This review summarizes the findings about the role of Th17 cells in arthritis and discusses the impact of the different Th17 cytokines in the pathogenesis of this disease. However, further studies are needed to unravel the interplay between IL-17A and other Th17 cytokines such as IL-17F, IL-22, and IL-21 in the pathoimmunological process of this crippling disease, in particular, whether regulating Th17 cell activity or specific combinations of Th17 cytokines will have additional value compared to neutralizing IL-17A activity alone. Moreover, tumor necrosis factor-positive Th17 cells are discussed as potential dangerous cells in driving persistent arthritis in human early RA.

Translational mini-review series on Th17 cells: development of mouse and human T helper 17 cells

There has been a considerable amount of interest in the immunological community about new phenotypic subsets of CD4(+) T cells, particularly cells that produce the cytokine interleukin (IL)-17 [named T helper type 17 (Th17) cells]. While the initial discovery of Th17 cells and the pathways that controlled their development was in the mouse, recent attention has shifted to the existence of these cells and the relevant upstream cytokine signals in humans. While it is clear that CD4(+) T cells producing IL-17 exist in vivo, their relevance to disease pathogenesis is only just being understood. In this paper, we review the data regarding the generation of human Th17 cells in vitro and the evidence that this effector population is important in human disease states.

Plasma IL-17A is increased in new-onset SLE patients and associated with disease activity

OBJECTIVE

To investigate the role of interleukin-17A (IL-17A) and Th17 cell in the pathogenesis of systemic lupus erythematosus (SLE), we studied the plasma IL-17A and the expression of Th17 cell transcription factor RORgammat in Chinese new-onset SLE patients.

METHODS

Sixty SLE patients aged between 18 and 40 years and 56 age-matched healthy volunteers were involved in the study. Enzyme-linked immunosorbent assay was used to measure plasma IL-17A level, and rea1-time fluorescent quantitative polymerase chain reaction was used to measure RORgammat mRNA.

RESULTS

The results showed that both IL-17A level and RORgammat mRNA in SLE patients were higher than that of controls. Correlation analysis indicated that plasma IL-17A level was positively correlated with Systemic Lupus Erythematosus Disease Activity Index, not with RORgammat mRNA.

CONCLUSION

We concluded that IL-17A might play a role in the pathogenesis of SLE and associated with disease activity. RORgammat-determined Th17 cell might be involved with increased IL-17A in SLE but not exclusively the unique source.