IL-4-induced immune deviation as antigen-specific therapy for inflammatory autoimmune disease

Elucidation of stannin function using microarray analysis: implications for cell cycle control

Stannin (Snn) is a highly conserved, vertebrate protein whose cellular function is unclear. We have recently demonstrated in human umbilical vein endothelial cells (HUVECs) that Snn gene expression is significantly induced by tumor necrosis factor-alpha (TNF-alpha) in a protein kinase C-epsilon (PKC-epsilon)-dependent manner. In HUVEC, TNF-alpha stimulation of HUVECs results in altered gene expression, and a slowing or halting of cell growth. An initial set of experiments established that Snn knockdown via siRNA, prior to TNF-alpha treatment, resulted in a significant inhibition of HUVEC growth compared to TNF-alpha treatment alone. In order to assess how Snn may be involved in TNF-alpha signaling in HUVEC growth arrest, we performed microarray analysis of TNF-alpha-stimulated HUVECs with and without Snn knockdown via siRNA. The primary comparison made was between TNF-alpha-stimulated HUVECs and TNF-alpha-exposed HUVECs that had Snn knocked down via Snn-specific siRNAs. Ninety-six genes were differentially expressed between these two conditions. Of particular interest was the significant upregulation of several genes associated with control of cell growth and/or the cell cycle, including interleukin-4, p29, WT1/PRKC, HRas-like suppressor, and MDM4. These genes act upon cyclin D1 and/or p53, both of which are key regulators of the G1 phase of the cell cycle. Functional studies further supported the role of Snn in cell growth, as cell cycle analysis using flow cytometry shows a significant increase of G1 cell cycle arrest in HUVECs with Snn knockdown in response to TNF-alpha treatment. Together these studies suggest a functional role of Snn in regulation of TNF-alpha-induced signaling associated with HUVEC growth arrest.

Role of interleukin-4 in atherosclerosis

Vascular endothelial cell injury or dysfunction has been implicated in the onset and progression of cardiovascular diseases including atherosclerosis. A number of previous studies have demonstrated that the pro-oxidative and pro-inflammatory pathways within vascular endothelium play an important role in the initiation and progression of atherosclerosis. Recent evidence has provided compelling evidence to indicate that interleukin-4 (IL-4) can induce pro-inflammatory environment via oxidative stress-mediated up-regulation of inflammatory mediators such as cytokine, chemokine, and adhesion molecules in vascular endothelial cells. In addition, apoptotic cell death within vascular endothelium has been hypothesized to be involved in the development of atherosclerosis. Emerging evidence has demonstrated that IL-4 can induce apoptosis of human vascular endothelial cells through the caspase-3-dependent pathway, suggesting that IL-4 can increase endothelial cell turnover by accelerated apoptosis, the event which may cause the dysfunction of the vascular endothelium. These studies will have a high probability of revealing new directions that lead to the development of clinical strategies toward the prevention and/or treatment for individuals with inflammatory vascular diseases including atherosclerosis.

Experimental research on treatment of ulcerative colitis with integrative traditional Chinese and Western medicine

AIM: To explore the effect of the clyster treatment with integrated traditional Chinese and Western medicine on ulcerative colitis (UC), and to investigate its mechanism.

METHODS: The mouse model of UC was established, and then the rats were treated (clyster) with the combination of tin-like powder, dexamethasone, gentamicin, and berberine. Then the therapeutic effect was observed, and the mechanism of the treatment was analyzed.

RESULTS: The disease active index (DAI) and histopathologic score (HPS) of the low dose (DAI: 5.10±4.07, HPS: 8.00±6.38), the moderate dose (DAI: 0.80±1.87, HPS: 1.30±1.49), the high dose (DAI: 1.00±1.94, HPS: 0.90±1.45), and the positive control group (DAI: 5.30±4.37, HPS: 8.00±5.12) were markedly lower than those of the negative control group (DAI: 8.60±1.26, HPS: 13.20±1.69) (all P <0.05). The DAI and HPS of the moderate dose group were markedly lower than those of the low dose group and the positive control group (all P <0.05), but there was no significant difference between the moderate and high dose group (P >0.05). The levels of interleukin-4 (IL-4) of the low, moderate, and high dose group, and the positive control group were markedly lower than those of the negative control group (32.33±15.30, 25.79±6.33, 29.92±12.81, 28.45±9.30 vs 63.89±11.31, all P <0.05), but the levels of interferon-γ (IFN-γ) were markedly higher than those of the negative control group (198.38±31.46, 187.49±13.04, 188.14±14.11, 207.64±41.44 vs 127.41±21.47, all P <0.05).

CONCLUSION: The combination enema of tin-like powder, dexamethasone, gentamicin, and berberine has definite therapeutic effect on UC, which may be related with its regulation on IL-4 and IFN-γ level.

ERK1-deficient mice show normal T cell effector function and are highly susceptible to experimental autoimmune encephalomyelitis

T cell activation engages multiple intracellular signaling cascades, including the ERK1/2 (p44/p42) pathway. It has been suggested that ERKs integrate TCR signal strength, and are important for thymocyte development and positive selection. However, the requirement of ERKs for the effector functions of peripheral mature T cells and, specifically, for T cell-mediated autoimmunity has not been established. Moreover, the specific requirements for ERK1 vs ERK2 in T cells have not been resolved. Therefore, we investigated the role of ERK1 in T cell immunity to foreign and self Ags and in the induction of experimental autoimmune encephalomyelitis. The results show that in ERK1-deficient (ERK1-/-) mice, the priming, proliferation, and cytokine secretion of T cells to the self Ag myelin oligodendrocyte glycoprotein peptide 35-55 and to the prototypic foreign Ag OVA are not impaired as compared with wild-type mice. Furthermore, ERK1-/- mice are highly susceptible to experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein peptide 35-55. Finally, thymocyte development and mitogen-induced proliferation were not impaired in ERK1-/- mice on the inbred 129 Sv and C57BL/6 backgrounds. Collectively, the data show that ERK1 is not critical for the function of peripheral T cells in the response to self and foreign Ags and in T cell-mediated autoimmunity, and suggest that its loss can be compensated by ERK2.

In vitro Th2 deviation of myelin-specific peripheral blood lymphocytes from patients with multiple sclerosis

This study aimed at investigating if selective ex vivo immune deviation of myelin-specific cytokine secretion towards Th2 is possible in blood cells from patients with multiple sclerosis (MS). Interleukin (IL)-4 (Th2) and interferon-gamma (Th1) secreting cells were recorded by ELISPOT in 13 MS patients. Deviation was successful in 10 patients. Interleukin-4 alone was most effective in inducing myelin-specific immune deviation in MS patients whereas IL-1 or IL-15 in combination with IL-4 did not improve the results. Further studies and improvements are needed before ex vivo immune deviation can be considered a potential treatment in patients with MS.

Gene expression profile in interleukin-4-stimulated human vascular endothelial cells

Interleukin-4 (IL-4)-mediated pro-oxidative and pro-inflammatory vascular environments have been implicated in the pathogenesis of atherosclerosis. The cellular and molecular regulatory mechanisms underlying this process, however, are not fully understood. In the present study, we employed GeneChip microarray analysis to investigate global gene expression patterns in human vascular endothelial cells after treatment with IL-4. Our results showed that mRNA levels of a total of 106 genes were significantly up-regulated and 41 genes significantly down-regulated with more than a 2-fold change. The majority of these genes are critically involved in the regulation of inflammatory responses, apoptosis, signal transduction, transcription factors, and metabolism; functions of the remaining genes are unknown. The changes in gene expression of selected genes related to inflammatory reactions, such as vascular cell adhesion molecule-1 (VCAM-1), E-selectin, monocyte chemoattractant protein-1 (MCP-1), and interleukin-6 (IL-6), were verified by quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) analyses. IL-4 treatment also significantly increased the adherence of inflammatory cells to endothelial cell monolayers in a dose-dependent manner. These results may help determine the molecular mechanisms of action of IL-4 in human vascular endothelium. In addition, a better understanding of IL-4-induced vascular injury at the level of gene expression could lead to the identification of new therapeutic strategies for atherosclerosis.

T cell reactivity to P0, P2, PMP-22, and myelin basic protein in patients with Guillain-Barre syndrome and chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVES

It has been suggested that autoimmunity to peripheral myelin proteins is involved in the pathogenesis of Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). We aimed to compare reactivity of peripheral blood mononuclear cells (PBMC) to antigens of peripheral myelin proteins in patients with GBS and patients with CIDP with that of healthy controls and patients with other non-immune mediated neuropathies (ON).

METHODS

We prepared PBMC from blood from 83 healthy controls and from 64 patients with GBS, 54 with CIDP, and 62 with ON. PBMC were tested in antigen specific proliferation assays against peptides from myelin proteins P0, P2, PMP22, and myelin basic protein (MBP), which is identical to myelin P1, and against whole human MBP. Interferon-gamma (IFN-gamma) and interleukin (IL)-5 enzyme linked immunospot (ELISPOT) assays were also performed in some subjects to assess spontaneous and peripheral myelin antigen specific PBMC cytokine secretion.

RESULTS

Antigen specific PBMC proliferation assays showed no significant elevation of peptide specific T cell responsiveness in patients with GBS or CIDP compared with healthy controls or patients with ON. Levels of spontaneous ELISPOT IFN-gamma secretion were increased in patients with GBS and significantly increased in those with CIDP compared with healthy controls and patients with ON. No convincing differences in antigen specific ELISPOT IFN-gamma secretion levels to individual peptides were detectable in patients with GBS. The proportion of patients with CIDP with an increased number of PBMC producing IFN-gamma in response to peptide PMP-22(51-64) was significantly increased compared with healthy controls and patients with ON. No significant differences in antigen specific ELISPOT IL-5 secretion levels were detectable in patients with GBS or CIDP compared with controls, but levels of spontaneous IL-5 secretion were significantly higher in patients with CIDP than in healthy controls or patients with ON.

CONCLUSIONS

Although the lack of significantly increased antigen specific PBMC proliferation in GBS and CIDP does not support a role for T cells, the more sensitive ELISPOT technique detected increased numbers of PBMC secreting IFN-gamma spontaneously in 25% of patients with GBS, providing further evidence for a role of T cells in the immunopathology of GBS. Increased numbers of spontaneous IFN-gamma and IL-5 secreting cells, and increased IFN-gamma secretion in response to PMP-22(51-64), in patients with CIDP provide further evidence for a role of myelin specific T cells in CIDP.

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Antigen-specific therapies for the treatment of multiple sclerosis: a clinical trial update

Within the past year a host of antigen-specific therapies for multiple sclerosis (MS) progressed along the path from IND submission to FDA approval. The Immune Response Corporation vaccinated patients with a Vbeta6 peptide, demonstrating that the vaccine was immunogenic, well tolerated, and reduced the number of Vbeta6+ T-cells in the cerebrospinal fluid (CSF). Connetics Corp. conducted a Phase I/II trial on chronic progressive MS patients vaccinated with CDR2 peptides from TCR Vbeta55.2 and found that patients with a measurable response to the vaccine remained clinically stable for a year. A study at the University of Alberta MS Patient Care and Research Clinic demonstrated that intrathecal injection of a B cell/T cell epitope of myelin basic protein (MBP) decreased the level of antiMBP antibody, but iv. administration did not decrease the relapse rate. AutoImmune Inc. completed a Phase III trial of oral myelin in the spring of 1997 which failed to show a statistical difference between those patients fed placebo and those fed daily capsules of myelin protein (Myoral). Three phase I trials of iv. myelin antigen(s) were initiated: MP4 (Alexion Pharmaceuticals, Inc.), a recombinant fusion of myelin basic protein and proteolipid protein; AG284 (Anergen, Inc.), a solubilised HLA-DR2:MBP peptide complex; and NBI-5788 (Neurocrine Biosciences, Inc.), an altered peptide ligand of an immunodominant MBP T-cell epitope. Following the conclusion of a successful Phase III clinical trial, TEVA Pharmaceutical Industries LTD received FDA approval to market Copaxone (glatiramer acetate) for the treatment of relapsing-remitting MS in December of 1996 and launched the product in 1997. The recent preclinical research and clinical trial status of these antigen-specific MS therapeutics are summarized in this review.

TH1 and TH2 lymphocyte development and regulation of TH cell-mediated immune responses of the skin

Since the first description of the subpopulations of TH1 and TH2 cells, insights into the development and control of these cells as two polarized and physiologically balanced subsets have been generated. In particular, implications of the TH1-TH2 concept for TH cell-mediated skin disorders have been discovered. This article will review the basic factors that control the development of TH1 and TH2 cells, such as the cytokines IL-12 and IL-4 and transcription factors, the possible role of costimulatory molecules, and specialized dendritic cell populations. These regulatory mechanisms will be discussed in the context of polarized TH1 or TH2 skin disorders such as psoriasis and atopic dermatitis. Also presented are the principles that govern how chemokines and chemokine receptors recruit TH1 and TH2 cells to inflammatory sites and how they amplify these polarized TH cell responses. All of these concepts, including a novel role for IL-4-inducing TH1 responses, can contribute to the design of better therapeutic strategies to modulate TH cell-mediated immune responses.

T cell epitope spreading to myelin oligodendrocyte glycoprotein in HLA-DR4 transgenic mice during experimental autoimmune encephalomyelitis

Epitope spreading has been implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and human multiple sclerosis (MS). T cell epitope spreading has been demonstrated in rodents for myelin basic protein (MBP) and proteolipid protein (PLP) determinants, but not for myelin oligodendrocyte glycoprotein (MOG), another important myelin antigen. Moreover, the role of human autoimmunity-associated MHC molecules in epitope spreading, including HLA-DR2 and DR4, has not been formally examined. To address these questions, we investigated epitope spreading to MOG determinants in HLA-DR4 (DRB1*0401) transgenic mice during EAE. The data show that upon induction of EAE in HLA-DR4 transgenic mice with the immunodominant HLA-DR4-restricted MOG peptide 97-108 (MOG(97-108); TCFFRDHSYQEE), the T cell response diversifies over time to MOG(181-200) (core: MOG(183-191); FVIVPVLGP) and MBP. The spreading epitope MOG(181-200) binds with high affinity to HLA-DRB1*0401 and is presented by human HLA-DRB1*0401+antigen presenting cells. Moreover, this epitope is encephalitogenic in HLA-DRB1*0401 transgenic mice. This study demonstrates intra- and intermolecular epitope spreading to MOG and MBP in "humanized" HLA-DR4 transgenic mice.

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Dendritic cells: friend or foe in autoimmunity?

The large amount of information that has been acquired from human and animal models substantiates that the DC lineage system represents a double-edged sword in the immune system. Presumably, in normal physiology, tolerizing DCs guard against autoimmunity and control established immune reactions, whereas immunogenic DCs provide active host defenses. In autoimmune diseases, there is strong evidence to support the idea that tolerance is overridden by the development of immunogenic DCs that favor cross-priming. Based on the wide range of possible clinical applications, it is not surprising that manipulation of DCs for clinical benefit is rampant. Indeed, multiple clinical strategies are currently underway, including the development of DC immunotherapy for cancer vaccines and graft survival. In cancer, DC-based vaccines for solid tumors, such as melanoma, were well-tolerated and produced beneficial antitumor responses, even in patients who had advanced disease. Although initial trials such as these are highly promising, the ultimate goal is to develop DC-based strategies that will lead to highly specific, long-lasting immunity against the cancer cells. In autoimmune diseases and transplant settings, the goal is to devise strategies that will block the initiation and maintenance of autoreactive and antigraft responses, respectively. Specific strategies for autoimmune diseases might include interference with cross-priming events that activate autoreactive T cells and genetic engineering to introduce molecules that have immunosuppressive functions, such as IL-10, TGF3, Fas ligand, ILT3, and ILT4. Successful application to these diseases will necessitate high specificity. In this regard, recent preliminary studies that described antigen-specific suppression of a primed immune response by tolerogenic DCs are especially informative.

Effects of glycoprotein isolated from Rhus verniciflua stokes on TPA-induced apoptosis and production of cytokines in cultured mouse primary splenocytes

Glycoprotein of Rhus verniciflua Stokes (RVS glycoprotein) was isolated and identified using SDS-PAGE. To study the anti-apoptotic effects of RVS glycoprotein on mouse splenocytes, splenocytes were exposed to 100 nM TPA (61.68 ng/ml) for 3 h with or without RVS glycoprotein (100 microg/ml). Results from our experiment showed that RVS glycoprotein protects from splenocyte apoptosis induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). We also studied the effects of RVS glycoprotein on the proliferation of T/B cells and the production of cytokines. Our results showed that Concanavalin A (Con A)-induced T cell proliferation and the production of interleukin-2 (IL-2)/interleukin-4 (IL-4) were reduced, and that Lipopolysaccharide (LPS)-induced B cell proliferation and the Tumor necrosis factor alpha (TNF-alpha) were reduced significantly by the addition of 50 microg/ml RVS glycoprotein (P<0.01), compared to the control. These results indicate that RVS glycoprotein has the capacity to modulate apoptosis, cytokine production and T/B cell proliferation in splenocytes.

Lower prevalence of IL-4 receptor alpha-chain gene G variant in very-low-birth-weight infants with necrotizing enterocolitis

BACKGROUND/PURPOSE

Altered production of immunoregulatory cytokines is associated with the development of necrotizing enterocolitis (NEC) in preterm very low-birth-weight (VLBW) infants. According to data obtained in adults, functional genetic polymorphisms influence cytokine production capacity. The aim of this study was to evaluate whether functional polymorphisms of interleukin (IL)-1beta, IL-4 receptor alpha-chain (IL-4ra), IL-6, and IL-10 genes might be associated with the risk of NEC in VLBW infants.

METHODS

Dried blood spot samples of 46 VLBW infants with NEC were analyzed using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods. Samples from 90 VLBW infants without NEC were used as controls.

RESULTS

Infants with NEC carried the mutant variant of IL-4ra less frequently than controls (0.125 v 0.224; P <.05) even after adjustment for risk factors of NEC. No significant differences were found in the allelic frequencies of IL-1beta, IL-6, and IL-10 genes between NEC and control infants.

CONCLUSIONS

Carrier state of IL-4ra mutant allele might be associated with lower risk of NEC in VLBW infants. This genetic variant is associated with enhanced IL-4 effect. IL-4 is a major regulator of Th1-Th2 shift. The authors hypothesize that infants carrying the IL-4ra mutant allele might have Th2 skewness that might defend against the development of NEC.

Caspase-mediated oligodendrocyte cell death in the pathogenesis of autoimmune demyelination

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by localized areas of demyelination. MS is believed to be an autoimmune disorder mediated by activated immune cells such as T- and B-lymphocytes and macrophages/microglia. Lymphocytes are primed in the peripheral tissues by antigens, and clonally expanded cells infiltrate the CNS. They produce large amounts of inflammatory and cytokines that lead to demyelination and axonal degeneration. Although several studies have shown that oligodendrocytes (OLGs), the myelin-forming glial cells in the CNS, are sensitive to cell death stimuli, such as cytotoxic cytokines, anti-myelin antibodies, nitric oxide, and oxidative stress, in vitro, the mechanisms underlying injury to the OLGs in MS/EAE remain unclear. Transgenic mice that express the anti-apoptotic protein specifically in OLGs and caspase-11-deficient mice are significantly resistant to EAE induction. Histopathological analyses show that the number of caspase-activated OLGs and dead OLGs are reduced in the CNS of these mice. The numbers of infiltrating immune cells and the amounts of cytokines are also markedly reduced in EAE lesions. Therefore, caspase-mediated OLG death leads to the exacerbation of demyelination and the deterioration of neurological manifestations by inducing local inflammatory events.

Immunpathogenese der Psoriasis. Immunopathogenesis of Psoriasis

Psoriasis is a chronic inflammatory disease of the skin and the joints. Multiple factors contribute to the initiation of psoriasis. They include specific genetic characteristics such as major histocompatibility antigens and psoriasis susceptibility genes, as well as trigger factors, namely streptococcal infections. Today, psoriasis is considered as a T-lymphocyte mediated autoimmune disease, even though the putative autoantigen remains unknown. Bacterial proteins with similarity to structural proteins of keratinocytes are potential target antigens. As in other autoimmune diseases, inflammatory cytokines of the innate immune system initiate a cascade that activates inflammation locally in the skin, in the circulation and most likely also in lymph nodes. IFN-gamma-producing CD4+ Th1-lymphocytes seem to be of central importance in the pathogenesis of psoriasis as they critically influence differentiation and functioning of antigen presenting cells, mast cells, neutrophils and endothelial cells. This inflammatory cascade simultaneously provokes neoangiogenesis in the dermis and proliferation of keratinocytes. Based on this hypothesis, cytokines or anticytokine antibodies that either inhibit T-cell mediated inflammation or transform disease-inducing, pro-inflammatory Th1-lymphocytes into a phenotype with anti-inflammatory properties were tested in psoriasis. As both approaches improved psoriasis, they strongly support the current concept that views psoriasis as a Th1-lymphocyte mediated disease.

Decreased expression of Src homology 2 domain-containing protein tyrosine phosphatase 1 reduces T cell activation threshold but not the severity of experimental autoimmune myasthenia gravis

Myasthenia gravis (MG) and its murine model experimental autoimmune myasthenia gravis (EAMG) are T cell-dependent, antibody-mediated autoimmune diseases. Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1) is a cytosolic tyrosine phosphatase that is involved in regulating the T cell activation cascade from signals initiated through the TCR. To study the role of SHP-1 in EAMG pathogenesis, we immunized C57BL/6 (B6) mice heterozygous for deletion of the SHP-1 gene (me(v+/-)) and their littermate wild type B6 mice with torpedo acetylcholine receptor (TAChR). T cell proliferation and IFNgamma production were significantly increased in B6.me(v+/-) mice after immunization with AChR compared to that of wild type littermates. However, clinical incidence and severity of the disease were not changed. There also were no significant differences in AChR-specific antibodies produced between wild type and me(v+/-) mice. These data suggest that deficiency in SHP-1 expression does decrease the activation threshold of autoreactive T cells in EAMG, but the increased frequency of autoreactive T cells does not aggravate EAMG in terms of clinical score, incidence, or antibody titers.

In vivo blockade of macrophage migration inhibitory factor ameliorates acute experimental autoimmune encephalomyelitis by impairing the homing of encephalitogenic T cells to the central nervous system

Macrophage migration inhibitory factor (MIF) is a cytokine that plays a critical role in the regulation of macrophage effector functions and T cell activation. However, its role in the pathogenesis of T cell-mediated autoimmune diseases, such as experimental autoimmune encephalomyelitis (EAE), has remained unresolved. In this study, we report that anti-MIF Ab treatment of SJL mice with acute EAE improved the disease severity and accelerated the recovery. Furthermore, the anti-MIF treatment impaired the homing of neuroantigen-reactive pathogenic T cells to the CNS in a VCAM-1-dependent fashion. Interestingly, MIF blockade also decreased the clonal size of the neuroantigen-specific Th1 cells and increased their activation threshold. Taken together, the results demonstrate an important role for MIF in the pathogenesis of EAE/multiple sclerosis and suggest that MIF blockade may be a promising new strategy for the treatment of multiple sclerosis.

IL-4 responsive CD4+ T cells specific for myelin basic protein: IL-2 confers a prolonged postactivation refractory phase

This study compared myelin basic protein-specific T cells from Lewis rats that were derived in the presence of either rat IL-4 or IL-2. Interleukin-4 was a maintenance factor that enabled derivation of long-term T cell lines. When activated, IL-4 dependent lines were lacking in IL-2 production capacity but maintained high levels of responsiveness to IL-2 and recognized IL-2 as a dominant growth factor. Activated IL-4 dependent T cells rapidly reverted to a quiescent phenotype in the presence of IL-4 and rapidly regained myelin basic protein reactivity. In contrast, activated IL-2 dependent T cells that were propagated in IL-2 had a more persistent blastogenic phenotype and a prolonged refractory phase. Interleukin-4 dependent lines that were propagated in IL-2 up-regulated the capacity to produce IL-2 and also acquired prolonged postactivation refractoriness. Thus, IL-2 was a dominant growth factor that conferred prolonged activation-dependent non-responsiveness. The coupling of dominant growth factor activity with prolonged postactivation refractoriness may be associated with the requisite role of IL-2 in homeostatic self-tolerance.

Autoreactive T cells promote post-traumatic healing in the central nervous system

In general, autoimmune responses are considered harmful to the host. In the best-defined model of autoimmune disease, murine experimental allergic encephalomyelitis (EAE), for example, brain-protein-specific autoimmune responses of both major classes, type-1 and type-2, have been implicated in causing brain pathology. We induced type-1 and type-2 autoimmunity to myelin oligodendrocyte protein (MOG) in C57.BL/6 mice. Instead of using pertussis toxin (PTX) to open the blood-brain barrier (BBB), which is the classic procedure, we set an aseptic cerebral injury (ACI) to see what the consequences of pre-primed, autoreactive type-1 and type-2 memory T cells gaining access to the brain in the course of sterile tissue injury would be. Neither of these autoimmune response types induced pathology; on the contrary, both accelerated re-vascularization and post-traumatic healing. The data suggest that induction of either type-1 or type-2 autoimmune responses is not inherently noxious to the host, but can have beneficial effects on tissue repair. Autoimmune pathology may develop only if molecules of microbial origin such as pertussis toxin additionally induce the "infectious nonself/danger" reaction in the antigen-presenting cells (APC) of the target organ itself.

Redox-regulated mechanisms of IL-4-induced MCP-1 expression in human vascular endothelial cells

The present study focused on the molecular signaling pathways of monocyte chemoattractant protein-1 (MCP-1) induction by interleukin-4 (IL-4) in human umbilical vein endothelial cells (HUVEC). RT-PCR showed that MCP-1 mRNA accumulation was markedly increased in IL-4-treated HUVEC in a time- and dose-dependent manner. Antioxidants, such as pyrrolidine dithiocarbamate (PDTC) and N-acetylcysteine (NAC), significantly inhibited IL-4-induced MCP-1 mRNA expression. These effects correlated well with the PDTC-mediated inhibition of MCP-1 promoter transcriptional activity observed in IL-4-treated HUVEC. IL-4-induced MCP-1 gene expression was paralleled by a concomitant production of MCP-1 protein. In agreement with MCP-1 gene expression, PDTC attenuated IL-4-mediated induction of MCP-1 protein expression. In addition, IL-4 dramatically increased the transcription factor signal transducers and activators of transcription 1 (STAT1) DNA binding activity, an effect that was attenuated by PDTC. The role of STAT1 in the regulation of the IL-4-induced MCP-1 gene expression was further confirmed in HUVEC transfected with a reporter construct of the MCP-1 promoter with a mutated STAT1 binding site. These results demonstrate that IL-4-dependent MCP-1 induction in HUVEC is mediated by redox-regulated STAT1 activation.

New immunopathologic insights into multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system. Although the immune system seems to play an important role in the pathogenesis of disease, target antigens are still uncertain and pathways leading to tissue destruction have not been fully elucidated. Recent studies have significantly contributed to a better understanding of the disease process and broadened our view on possible scenarios of disease initiation and progression. We review the role of the immune system for the manifestation and evolution of MS and discuss different pathogenetic concepts. We conclude with an outlook on future strategies to identify the cause of MS.

Antinociceptive effects of interleukin-4, -10, and -13 on the writhing response in mice and zymosan-induced knee joint incapacitation in rats

The antinociceptive effects of interleukin (IL)-4, -10, and -13 were investigated in two different experimental pain models. Our results showed that pretreatment (30 min) with IL-4 (1-5 ng/animal), IL-10 (0.4-10 ng/animal), or IL-13 (0.4-2.5 ng/animal) inhibited the writhing response induced by the i.p. administration of acetic acid (53-89%) or zymosan (63-74%) in mice, and the knee joint incapacitation induced by i.a. injection of zymosan (49-66%) in rats. Neither of the cytokines affected the pain elicited in mice using the hot-plate test. This analgesic effect of IL-4, -10, and -13 was not reversed by the combined pretreatment with the opioid receptor antagonist naloxone. IL-4, -10, or -13 significantly inhibited the release of both tumor necrosis factor (TNF)-alpha (60, 53, and 100%, respectively) and IL-1beta (80, 100, and 100%, respectively) by mice peritoneal macrophages obtained after local (i.p.) injection of zymosan. Antisera against IL-4, -10, and -13 potentiated both the zymosan-induced writhing response and the articular incapacitation. Our results demonstrate that IL-4, -10, and -13 display analgesic activity that is probably not due to endogenous opioid release. This analgesic effect could be related to a peripheral mechanism, probably via the inhibition of the release of the pro-inflammatory cytokines TNF-alpha and IL-1beta by resident peritoneal macrophages.

Interleukin-4 therapy of psoriasis induces Th2 responses and improves human autoimmune disease

Selective skewing of autoreactive interferon-gamma (IFN-gamma)-producing T helper cells (Th1) toward an interleukin-4 (IL-4)-producing (Th2) phenotype can in experimental animals alleviate autoimmune disease without inducing general immunosuppression. In a prospective dose escalation study, we assessed treatment with human IL-4 (rhuIL-4) in 20 patients with severe psoriasis. The therapy was well tolerated, and within six weeks all patients showed decreased clinical scores and 15 improved more than 68%. Stable reduction of clinical scores was significantly better at 0.2-0.5 microg rhuIL-4 than at < or =0.1 microg rhuIL-4 (P = 0.009). In psoriatic lesions, treatment with 0.2-0.5 microg/kg rhuIL-4 reduced the concentrations of IL-8 and IL-19, two cytokines directly involved in psoriasis; the number of chemokine receptor CCR5+ Th1 cells; and the IFN-gamma/IL-4 ratio. In the circulation, 0.2-0.5 microg/kg rhuIL-4 increased the number of IL-4+CD4+ T cells two- to three-fold. Thus, IL-4 therapy can induce Th2 differentiation in human CD4+ T cells and has promise as a potential treatment for psoriasis, a prototypic Th1-associated autoimmune disease.

Dual roles for IFN-gamma, but not for IL-4, in spontaneous autoimmune thyroiditis in NOD.H-2h4 mice

Spontaneous autoimmune thyroiditis (SAT) is an organ-specific autoimmune disease characterized by chronic inflammation of the thyroid by T and B lymphocytes. To investigate the roles of Th1 and Th2 cytokines in the pathogenesis of SAT, IFN-gamma(-/-) and IL-4(-/-) NOD.H-2h4 mice were generated. IL-4(-/-) mice developed lymphocytic SAT (L-SAT) comparable to that of wild-type (WT) mice. They produced little anti-mouse thyroglobulin (MTg) IgG1, but had levels of anti-MTg IgG2b comparable to WT mice. Compared with WT mice, IFN-gamma(-/-) mice produced significantly less anti-MTg IgG1 and IgG2b. Absence of IFN-gamma resulted in abnormal proliferation of thyroid epithelial cells with minimal lymphocyte infiltration. Thyroids of IFN-gamma(-/-) mice had markedly reduced B lymphocyte chemoattractant expression, B cell and plasma cell infiltration, and decreased MHC class II expression on thyrocytes compared with WT mice. Adoptive transfer of WT splenocytes to IFN-gamma(-/-) mice restored the capacity to develop typical L-SAT, enhanced anti-MTg IgG1 and IgG2b production, up-regulated MHC class II expression on thyrocytes and decreased thyrocyte proliferation. These results suggest that IFN-gamma plays a dual role in the development of SAT. IFN-gamma is required for development of L-SAT, and it also functions to inhibit thyroid epithelial cell proliferation.

Change of mouse CD5(+) B1 cells to a macrophage-like morphology induced by gamma interferon and inhibited by interleukin-4

The in vitro effects of gamma interferon (IFN-gamma) on the mouse CD5(+) B1-cell line, TH2.52, a hybridoma between mouse B lymphoma and mouse splenic B cells that expresses a series of B1 markers, were investigated. A significant number of macrophage-like cells appeared in the cultures of TH2.52 cells exposed to IFN-gamma, these adhering to plastic dishes and exhibiting phagocytic activity. Positive for esterase staining, the macrophage-like cells returned to the original TH2.52 morphology upon removal of IFN-gamma. The change was prevented by treatment with SB202190, an inhibitor of p38 mitogen-activated protein (MAP) kinase and by transfection of a p38 MAP kinase dominant-negative mutant. Further, interleukin-4 (IL-4) inhibited IFN-gamma-induced phosphorylation of p38 MAP kinase and the appearance of macrophage-like cells. IFN-gamma and IL-4 exhibited contradictory actions on morphological change of CD5(+) B1 cells into macrophage-like cells. Differential regulation of CD5(+) B1 cells by IFN-gamma, a Th1 cytokine, and IL-4, a Th2 cytokine, may have clear immunological significance.

Restriction of de novo pyrimidine biosynthesis inhibits Th1 cell activation and promotes Th2 cell differentiation

Leflunomide, an inhibitor of de novo pyrimidine biosynthesis, has recently been introduced as a treatment for rheumatoid arthritis in an attempt to ameliorate inflammation by inhibiting lymphocyte activation. Although the immunosuppressive ability of leflunomide has been well described in several experimental animal models, the precise effects of a limited pyrimidine supply on T cell differentiation and effector functions have not been elucidated. We investigated the impact of restricted pyrimidine biosynthesis on the activation and differentiation of CD4 T cells in vivo and in vitro. Decreased activation of memory CD4 T cells in the presence of leflunomide resulted in impaired generation and outgrowth of Th1 effectors without an alteration of Th2 cell activation. Moreover, priming of naive T cells in the presence of leflunomide promoted Th2 differentiation from uncommitted precursors in vitro and enhanced Th2 effector functions in vivo, as indicated by an increase in Ag-specific Th2 cells and in the Th2-dependent Ag-specific Ig responses (IgG1) in immunized mice. The effects of leflunomide on T cell proliferation and differentiation could be antagonized by exogenous UTP, suggesting that they were related to a profound inhibition of de novo pyrimidine biosynthesis. These results indicate that leflunomide might exert its anti-inflammatory activities in the treatment of autoimmune diseases by preventing the generation of proinflammatory Th1 effectors and promoting Th2 cell differentiation. Moreover, the results further suggest that differentiation of CD4 T cells can be regulated at the level of nucleotide biosynthesis.

Protective effect of prior acute immune challenge, but not footshock, on inflammation in the rat

Previous studies have revealed that a single exposure to an acute stress or acute immune stimulus can produce long-lasting changes in the activity and responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis. The HPA axis is believed to be an important component in determining the susceptibility and severity of inflammation in autoimmune disease models such as adjuvant-induced arthritis (AA). In the present study we have tested the hypothesis that a single exposure to either footshock or lipopolysaccharide (LPS) 3 weeks prior to adjuvant injection can alter susceptibility to AA. Changes in HPA axis parameters were also determined. The results demonstrated that prior exposure to LPS conferred resistance to inflammation in AA, which was not related to a delay in onset of inflammation but rather an alteration in susceptibility. In contrast, prior exposure to the acute stress of footshock did not alter susceptibility. HPA axis parameters were increased in adjuvant-injected rats whether inflammation was present or not. These data suggest that prior exposure to acute immune stimuli, but not to acute footshock stress, may alter susceptibility to inflammation in the rat AA model. These changes in susceptibility do not appear to be solely mediated by increases in HPA axis activity, which were apparent in all AA groups irrespective of the presence of inflammation.

Immunoregulation of CNS autoimmunity by helminth and mycobacterial infections

The 'hygiene hypothesis' has been proposed to explain apparent increases in autoimmune disease and allergy in areas of the world with improved health care and sanitation. This hypothesis proposes that the lack of serious childhood infections impairs development of an appropriately educated immune response. Imbalance of Th1 and Th2 responses and lack of regulatory T-cell populations are two of many proposed potential mechanisms for immune failures such as autoimmunity and allergy. We summarize the literature evidence for the influence of infectious organisms on autoimmunity with focus on helminth and mycobacterial infections. We also demonstrate that Schistosoma mansoni ova pretreatment, Mycobacterium bovis (BCG) infection, and lyophilized Mycobacterium tuberculosis all modify the course of clinical disease in mice induced for experimental autoimmune encephalomyelitis (a mouse model for human multiple sclerosis (MS)). Our data supports the applicability of the hygiene hypothesis to CNS autoimmune disease.

Preferential induction of IL-10 in APC correlates with a switch from Th1 to Th2 response following infection with a low pathogenic variant of Theiler's virus

Theiler's murine encephalomyelitis virus induces immune-mediated demyelination in susceptible mice after intracerebral inoculation. A naturally occurring, low pathogenic Theiler's murine encephalomyelitis virus variant showed a single amino acid change within a predominant Th epitope from lysine to arginine at position 244 of VP1. This substitution is the only one present in the entire viral capsid proteins. In this paper, we demonstrate that the majority of T cells specific for VP1(233-250) and VP2(74-86) from wild-type virus-infected mice are Th1 type and these VP1-specific cells poorly recognize the variant VP1 epitope (VP1(K244R)) containing the substituted arginine. In contrast, the Th2-type T cell population specific for these epitopes predominates in variant virus-infected mice. Immunization with UV-inactivated virus or VP1 epitope peptides could not duplicate the preferential Th1/Th2 responses following viral infection. Interestingly, the major APC populations, such as dendritic cells and macrophages, produce IL-12 on exposure to the pathogenic wild-type virus, whereas they preferentially produce IL-10 in response to the low pathogenic variant virus. Thus, such a spontaneous mutant virus may have a profoundly different capability to induce Th-type responses via selective production of cytokines involved in T cell differentiation and the consequent pathogenicity of virally induced immune-mediated inflammatory diseases.

Mycobacterial infection inhibits established allergic inflammatory responses via alteration of cytokine production and vascular cell adhesion molecule-1 expression

Our previous studies, as well as those of others, have demonstrated that local or systemic Mycobacterium bovis bacille Calmette-Guérin (BCG) infection can inhibit de novo allergen-induced asthma-like reactions, but the effect of this infection on established allergic responses is unknown. The aim of this study was therefore to examine the effect of mycobacterial infection on established allergy in a murine model of asthma-like reaction. Mice were sensitized with ovalbumin (OVA) in alum followed by infection with BCG and subsequent intranasal challenge with the same allergen. In some experiments, mice were sensitized with OVA followed by intranasal challenge with OVA and then given BCG infection with subsequent rechallenge with OVA. Mice without BCG infection but treated with OVA in the same manner, were used as a control. The mice were examined for immunoglobulin E (IgE) response and eosinophilic inflammation, mucus production, cytokine/chemokine patterns and adhesion molecule expression in the lung. The results showed that postallergen BCG infection suppressed the established airway eosinophilia and mucus overproduction, but not IgE responses. The inhibition of asthma-like reactions by BCG infection was correlated with a shift of allergen-driven cytokine production pattern and, more interestingly, with a dramatic decrease of vascular cell adhesion molecule-1 (VCAM-1) expression in the lung. These findings suggest that intracellular bacterial infection can inhibit established allergic responses via alteration of local cytokine production and the expression of adhesion molecules.

Th1 and Th2 responses in pathogenesis and regulation of experimental autoimmune uveoretinitis

Experimental autoimmune uveoretinitis (EAU) in animals can be induced by immunization with retinal antigens or their fragments and represents human uveitis of putative autoimmune origin. The pathogenesis of EAU, and likely also of human uveitis, involves cell-mediated destruction of retinal tissues that is dependent on retinal antigen-specific T cells. Because in most cases a Th1-type response has been implicated in pathogenesis, the prevailing consensus has been that immunoregulatory manipulations designed to enhance the Th2 response at the expense of the Th1 response will be beneficial in clinical treatment of uveitis. This assumption may not always be correct. The present review will summarize the evidence that, despite a central role for Th1 response in uveitis, an unopposed Th2-like response can be equally or more destructive to the retinal tissues. Furthermore, the Th1 response itself triggers regulatory circuits that feed back and dampen further recruitment of antigen-specific T cells into the Th1 effector pool. Thus, although the Th1 effector response can and does result in retinal pathology, immunoregulatory strategies must take into account that immune deviation therapies designed to replace the Th1 with a Th2 response might result in exchanging one type of pathology for another rather than in achieving the desired therapeutic effect.

Spontaneous secretion of interleukin-4, interleukin-10 and interferon-gamma by first trimester decidual mononuclear cells

PROBLEM

A T-helper cell type 2 (Th2) cytokine dominated microenvironment has been predicted to be crucial for successful pregnancy. However, little information is available about local cytokine secretion in the human decidua. We determined the spontaneous secretion of interleukin-4 (IL-4), interferon-gamma (IFN-gamma) and IL-10 by decidual mononuclear cells at the single cell level and compared it with their secretion by peripheral blood mononuclear cells (PBMC) in the first trimester of pregnancy.

METHODS OF STUDY

The cytokine secretion from decidual and blood cells was detected by a sensitive enzyme-linked immunosorbent spot-forming cell (ELISPOT)-assay.

RESULTS

Cells secreting IL-4 (median 153, range 8-530), IL-10 (median 188, range 32-1600) and IFN-gamma (median 123, range 15-1140) were detected in all decidual and blood samples. The cytokine secretion showed a co-linear pattern in both the blood and decidua, i.e. when one cytokine was secreted at high levels, the others followed the trend. No correlation was found between the number of cytokine secreting cells in blood and decidua for any of the cytokines.

CONCLUSIONS

Interleukin-4 and IL-10 are locally secreted in the decidua early during normal pregnancy, probably counteracting the fetal rejecting effects of co-expressed IFN-gamma. The cytokine secretion by blood cells does not generally reflect the local secretion pattern during first trimester pregnancy.

A lower prevalence of atopy symptoms in children with type 1 diabetes mellitus

BACKGROUND

The Th1/Th 2 concept is a model to understand the pathophysiology of certain diseases. Atopic diseases (asthma, eczema and hayfever) are characterized by a chronic inflammatory reaction that is dominated by Th 2 cells, and type 1 diabetes mellitus (DM) is Th1 cell dominated. Because it is known that Th1 and Th 2 cells reciprocally counteract each other, it can be speculated that the prevalence of Th 2-mediated disease is lower in patients with Th1-mediated disease.

OBJECTIVE

To compare the prevalence of atopic diseases between children with DM and age-matched controls.

METHODS

Parents of children with DM were requested by Dutch paediatricians to complete the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire on the prevalence of atopic diseases. A control group was derived from a Dutch cross-sectional survey (the ISAAC2 study).

RESULTS

We received 555 completed questionnaires, which is estimated to be 25% of the total number of Dutch children with DM. The control group consisted of 777 children. After age-matching, the questionnaires of 188 DM patients were used. Symptoms of asthma, hayfever and eczema were reported less in the group of children with DM compared with the control group (wheeze last year, OR 0.796, 95% CI 0.408-1.554; hayfever symptoms last year, OR 0.642, 95% CI 0.369-1.118; eczema symptoms last year, OR 0.693, 95% CI 0.430-1.115).

CONCLUSION

The lower prevalence of astma, hayfever and eczema symptoms in DM patients compared with age-matched controls, although not statistically significant, is consistent with the Th1/Th 2 concept.

The CD8 T cell compartment plays a dominant role in the deficiency of Brown-Norway rats to mount a proper type 1 immune response

Differential cytokine production by T cells plays an important role in regulating the nature of an immune response. In the rat, Brown-Norway (BN) and Lewis (LEW) strains differ markedly in their susceptibility to develop either type 1 or type 2-mediated autoimmune manifestations. BN rats are susceptible to type 2-dependent systemic autoimmunity, while LEW rats are resistant. Conversely, type 1-mediated, organ-specific autoimmune disease can be easily induced in LEW, but not in BN, rats. The mechanisms involved in the differential development of type 1 and type 2 immune responses by these two strains are still unknown. In the present study we analyzed the contributions of APC, CD4 and CD8 T cells, and MHC molecules in the difference between LEW and BN rats to develop a type 1 immune response. First, we show that the defect of BN T cells to produce type 1 cytokines in vitro does not require the presence of APC and, by using an APC-independent stimulation assay, we have localized the defect within the T cell compartment. Both CD4 and CD8 T cells are involved in the defect of BN rats to develop a type 1 immune response with a major contribution of the CD8 T cell compartment. This defect is associated with an increase in the type 2 cytokine IL-4 in both BN T cell populations, but neutralization of this cytokine does not restore this defect. Finally, by using MHC congenic rats, we show that the MHC haplotype is not involved in the defect of BN T cells to mount a proper type 1 cytokine response.

T cell epitopes of human myelin oligodendrocyte glycoprotein identified in HLA-DR4 (DRB1*0401) transgenic mice are encephalitogenic and are presented by human B cells

Myelin oligodendrocyte glycoprotein (MOG) is an Ag present in the myelin sheath of the CNS thought to be targeted by the autoimmune T cell response in multiple sclerosis (MS). In this study, we have for the first time characterized the T cell epitopes of human MOG restricted by HLA-DR4 (DRB1*0401), an MHC class II allele associated with MS in a subpopulation of patients. Using MHC binding algorithms, we have predicted MOG peptide binding to HLA-DR4 (DRB1*0401) and subsequently defined the in vivo T cell reactivity to overlapping MOG peptides by testing HLA-DR4 (DRB1*0401) transgenic mice immunized with recombinant human (rh)MOG. The data indicated that MOG peptide 97-108 (core 99-107, FFRDHSYQE) was the immunodominant HLA-DR4-restricted T cell epitope in vivo. This peptide has a high in vitro binding affinity for HLA-DR4 (DRB1*0401) and upon immunization induced severe experimental autoimmune encephalomyelitis in the HLA-DR4 transgenic mice. Interestingly, the same peptide was presented by human B cells expressing HLA-DR4 (DRB1*0401), suggesting a role for the identified MOG epitopes in the pathogenesis of human MS.

Immunological aspects of microglia: relevance to Alzheimer's disease

Alzheimer's disease (AD) is a progressive dementing neurologic illness, and the most frequent cause of dementia in the elderly. Neuritic plaques are one of the main neuropathological findings in AD, and the major protein component is the beta-amyloid protein (A beta). Another striking feature of neuritic plaques is the presence of activated microglia, cytokines, and complement components, suggestive of "inflammatory foci" within AD brain. In this review, we will examine the mechanisms by which microglia become activated in AD, emphasizing the role in the A beta protein and proinflammatory cytokines. As well, pathways for suppression of microglial activation by immunosuppressive cytokines will be described. Inflammation mediated by activated microglia is an important component of AD pathophysiology, and strategies to control this response could provide new therapeutic approaches for the treatment of AD.

IL-4 instructs TH1 responses and resistance to Leishmania major in susceptible BALB/c mice

Immunity to infection with intracellular pathogens is regulated by interleukin 12 (IL-12), which mediates protective T helper type 1 (TH1) responses, or IL-4, which induces TH2 cells and susceptibility. Paradoxically, we show here that when present during the initial activation of dendritic cells (DCs) by infectious agents, IL-4 instructed DCs to produce IL-12 and promote TH1 development. This TH1 response established resistance to Leishmania major in susceptible BALB/c mice. When present later, during the period of T cell priming, IL-4 induced TH2 differentiation and progressive leishmaniasis in resistant mice. Because immune responses developed via the consecutive activation of DCs and then T cells, the contrasting effects of IL-4 on DC development and T cell differentiation led to immune responses that had opposing functional phenotypes.

Distribution of Th1 and Th2 cell populations in human peripheral and decidual T cells from normal and anembryonic pregnancies

OBJECTIVE

To examine whether maternal immune responses during normal pregnancy are Th2 biased and whether there are specific changes when anembryonic pregnancy occurs.

DESIGN

Prospective study.

SETTING

Department of Obstetrics and Gynecology at a university hospital.

PATIENT(S)

We studied 32 pregnant women receiving elective abortions of normal pregnancies and 35 women with anembryonic pregnancies between 6 weeks and 10 weeks of gestational age.

INTERVENTION(S)

Using the multilabeling capability of three-color flow cytometry, it is possible to measure intracellular cytokines and cell surface markers simultaneously to determine which cells are the cytokine-producing cells.

MAIN OUTCOME MEASURE(S)

We examined the extent and proportion of mononuclear cells expressing specific T-cell surface markers and cytokines, interferon gamma, and interleukin 4 in the peripheral blood and deciduae. Secreted cytokines in the supernatants after 24-hour culture were also compared.

RESULT(S)

During the unstimulated status, the proportion of IL-4-secreting cells significantly exceeded that of IFN-gamma-secreting cells in the peripheral blood and decidua in normal pregnancies and was significantly decreased when anembryonic pregnancies occurred. Consequently, the Th1/Th2 ratios were increased during anembryonic pregnancies. However, after 24-hour culture, only another Th2-type cytokine, IL-10, was markedly increased and exceeded IFN-gamma secretion in cultures from both the peripheral blood and decidua in normal pregnancies.

CONCLUSION(S)

The decidual T lymphocytes are Th2 predominant. When anembryonic pregnancy occurs, this Th2 predominance disappears.

Predominance of Th1 immune response in diffuse proliferative lupus nephritis

OBJECTIVE

Lupus nephritis, which shows various histologic patterns, is a serious complication of systemic lupus erythematosus (SLE). We previously demonstrated the importance of Thl cell-mediated immune response in patients with diffuse proliferative lupus nephritis (DPLN). The aim of this study was to examine the relationship between the peripheral blood Th1/Th2 balance and the intrarenal immune response.

METHODS

The Th1:Th2 ratio in peripheral blood was measured by intracellular staining for cytokines with flow cytometry. Immunohistochemical analysis of renal biopsy specimens was performed to clarify the characterization of local infiltrating cells in 3 groups of subjects: SLE patients with World Health Organization (WHO) class IV nephritis (DPLN) (group I; n = 13), SLE patients with WHO class V nephritis (group II; n = 9), and patients with minor glomerular lesions (group III; n = 7). In addition, the histologic activity index and chronicity index were evaluated and correlated with the Th1:Th2 ratio.

RESULTS

Immunohistochemical studies showed higher numbers of CD68+ macrophages, CD3 + T cells, and interferon-gamma-positive cells in group I than in groups II or III. Renal tissues from patients in group I also showed up-regulation of expression of osteopontin and CD40, with a small number of infiltrating T cells expressing interleukin-4. Overall, the Thl:Th2 ratio in group I patients (SLE with DPLN) was high and correlated significantly with the histologic activity index, but not with the chronicity index.

CONCLUSION

We have identified a predominance of Thl-type response in both peripheral and renal tissues of patients with DPLN, suggesting that the peripheral blood Thl:Th2 ratio directly reflects the local histopathologic findings. In patients with lupus nephritis, the peripheral blood Th1:Th2 ratio could be useful as a parameter that reflects the renal histologic activity or the strength of the local Thl response.

Effect of targeted disruption of STAT4 and STAT6 on the induction of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is mediated by myelin-specific CD4(+) T cells secreting Th1 cytokines, while recovery from disease is associated with expression of Th2 cytokines. Investigations into the role of individual cytokines in disease induction have yielded contradictory results. Here we used animals with targeted deletion of the STAT4 or STAT6 genes to determine the role of these signaling molecules in EAE. The STAT4 pathway controls the differentiation of cells into a Th1 phenotype, while the STAT6 pathway controls the differentiation of cells into a Th2 phenotype. We found that mice deficient in STAT4 are resistant to the induction of EAE, with minimal inflammatory infiltrates in the central nervous system. In contrast, STAT6-deficient mice, which have a predominantly Th1 phenotype, experience a more severe clinical course of EAE as compared with wild-type or STAT4 knockout mice. In addition, adoptive transfer studies confirm the regulatory functions of a Th2 environment in vivo. These novel data indicate that STAT4 and STAT6 genes play a critical role in regulating the autoimmune response in EAE.

IL-4 abrogates osteoclastogenesis through STAT6-dependent inhibition of NF-kappaB

IL-4, an anti-inflammatory cytokine, inhibits osteoclast differentiation, but the basis of this effect has been unclear. Osteoclastogenesis requires activation of RANK, which exerts its biologic effect via activation of NF-kappaB. NF-kappaB activation is manifested by nuclear translocation and binding to DNA, events secondary to phosphorylation and dissociation of IkappaBalpha. It is shown here that IL-4 reduces NF-kappaB nuclear translocation by inhibiting IkappaB phosphorylation, thus markedly inhibiting NF-kappaB DNA binding activity and blocking osteoclastogenesis entirely. Residual translocation of NF-kappaB in the presence of IL-4, however, suggests that nuclear mechanisms must primarily account for inhibition of NF-kappaB DNA binding and blockade of osteoclastogenesis. To address this issue, this study examined whether IL-4-induced STAT6 transcription factor blocks NF-kappaB transactivation. The results show that excess unlabeled consensus sequence STAT6, but not its mutated form, inhibits NF-kappaB binding. Furthermore, exogenously added STAT6 protein inhibits NF-kappaB/DNA interaction. Further supporting a role for STAT6 in this process are the findings that IL-4 fails to block osteoclastogenesis in STAT6(-/-) mice but that this blockade can be restored with addition of exogenous STAT6. Thus, IL-4 obliterates osteoclast differentiation by antagonizing NF-kappaB activation in a STAT6-dependent manner.