B7-1 expression of Langerhans cells is up-regulated by proinflammatory cytokines, and is down-regulated by interferon-gamma or by interleukin-10

Erratum: Type 1 regulatory T cell-mediated tolerance in health and disease

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Type 1 regulatory T cell-mediated tolerance in health and disease

Type 1 regulatory T (Tr1) cells, in addition to other regulatory cells, contribute to immunological tolerance to prevent autoimmunity and excessive inflammation. Tr1 cells arise in the periphery upon antigen stimulation in the presence of tolerogenic antigen presenting cells and secrete large amounts of the immunosuppressive cytokine IL-10. The protective role of Tr1 cells in autoimmune diseases and inflammatory bowel disease has been well established, and this led to the exploration of this population as a potential cell therapy. On the other hand, the role of Tr1 cells in infectious disease is not well characterized, thus raising concern that these tolerogenic cells may cause general immune suppression which would prevent pathogen clearance. In this review, we summarize current literature surrounding Tr1-mediated tolerance and its role in health and disease settings including autoimmunity, inflammatory bowel disease, and infectious diseases.

IL-10 as a Th2 Cytokine: Differences Between Mice and Humans

The discovery of IL-10 more than 30 years ago marked the beginning of our understanding of how cytokines regulate immune responses, based on cross-regulation between Th1 and Th2 cytokines. Although multiple cell types were shown to produce IL-10, its identity as a Th2 cytokine remained strong because it was rigidly associated with Th2 clones in mice, whereas both Th1 and Th2 clones could secrete IL-10 in humans. However, as new Th1/Th2 cell functionalities emerged, anti-inflammatory action of IL-10 gained more attention than its inhibitory effect on Th1 cells, which may occur as an indirect consequence of suppression of APCs. This notion is also supported by the discovery of regulatory T cells, whose suppressor functions involve the mediation of IL-10, among other molecules. From this perspective, we discuss the functionalities of IL-10 by highlighting important differences between mice and humans with an emphasis on the Th1 and Th2 paradigm.

Regulation of cancer immune escape: The roles of miRNAs in immune checkpoint proteins

Immune checkpoint proteins (ICPs) are regulators of immune system. The ICP dysregulation silences the host immune response to cancer-specific antigens, contributing to the occurrence and progress of various cancers. MiRNAs are regulatory molecules and function in mRNA silencing and post-transcriptional regulation of gene expression. MiRNAs that modulate the immunity via ICPs have received increasing attention. Many studies have shown that the expressions of ICPs are directly or indirectly repressed by miRNAs in multiple types of cancers. MiRNAs are also subject to regulation by ICPs. In this review, recent studies of the relationship between miRNAs and ICPs (including the PD-1, PD-L1, CTLA-4, ICOS, B7-1, B7-2, B7-H2, B7-H3, CD27, CD70, CD40, and CD40L) in cancer immune escape are comprehensively discussed, which provide critical detailed mechanistic insights into the functions of the miRNA-ICP axes and their effects on immune escape, and will be beneficial for the potential applications of immune checkpoint therapy and miRNA-based guidance for personalized medicine as well as for predicting the prognosis.

The combination of IκB kinase β inhibitor and everolimus modulates expression of interleukin-10 in human T-cell lymphotropic virus type-1-infected T cells

Adult T-cell leukaemia-lymphoma (ATLL) is an aggressive malignancy of CD4(+)  CD25(+) T lymphocytes, characterized by a severely compromised immunosystem, in which the human T-cell lymphotropic virus type 1 (HTLV-1) has been recognized as the aetiological agent. This study found that an IκB kinase β (IKKβ) inhibitor Bay11-7082 inactivated mammalian target of rapamycin (mTOR), signal transducer and activator of transcription 3 and transcription factor nuclear factor-κB in HTLV-1-infected T cells; this was significantly enhanced in the presence of the mTOR inhibitor everolimus. In addition, Bay11-7082 decreased production of the immunosuppressive cytokine interleukin-10 (IL-10), which was further down-regulated when Bay11-7082 was combined with evelolimus in HTLV-1-infected T and ATLL cells isolated from patients. Interleukin-10 is known to inhibit maturation and the antigen-presenting function of dendritic cells (DCs). The culture media of HTLV-1-infected MT-1 cells, which contained a large amout of IL-10, hampered tumour necrosis factor-α-induced maturation of DCs isolated from healthy volunteers. Culture supernatant of MT-1 cells treated with a combination of Bay11-7082 and everolimus augmented maturation of DCs in association with a decrease in production of IL-10 and enhanced the allostimulatory function of DCs. Similarly, when DCs isolated from patients with ATLL were treated with the combination of Bay11-7082 and everolimus, they were fully matured and their capability to stimulate proliferation of lymphocytes was augmented. Taken together, the combination of Bay11-7082 and everolimus might exhibit immunostimulatory properties in HTLV-1-infected T and ATLL cells isolated from patients, and this combination may be potentially therapeutic to regain the compromised immunosystem in ATLL patients.

Granulocyte-macrophage colony-stimulating factor genetic adjuvant enhances the immune stimulatory effects of plasmid DNA encoding the hepatitis C virus core protein

AIM: To study the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) genetic adjuvant on immune response induced by plasmid DNA encoding the hepatitis C virus (HCV) core (C) protein.

METHODS: The gene encoding the HCV C protein was amplified by PCR from HCV 1b genotype and inserted into the pUC119 vector. The HCV C gene was then subcloned into the pCMH6K eukaryotic vector, and the resulting plasmid was named pCMH6K/HCV-C. The recombinant vector was confirmed by restriction enzyme analysis and DNA sequencing, and transfected into China hamster ovary (CHO) cells with Lipofectamine 2000. Distribution of the HCV C protein in transfected CHO cells was detected by immunofluorescence. Balb/c mice were vaccinated with the recombinant plasmid with or without the GM-CSF gene. HCV C-specific antibody in serum was measured by ELISA. The changes in T lymphocyte subsets and levels of Th cell intracellular cytokines interferon-γ (IFN-γ) and interleukin-4 (IL-4) in splenic cell suspension from immunized mice were evaluated by flow cytometric analysis. CTL activity was assessed by LDH assay.

RESULTS: Restrict enzyme digestion and DNA sequencing indicated that the recombinant pCMH6K/HCV-C was successfully constructed. The expression of plasmid-encoded protein was mainly distributed in membrane and scarcely in cytoplasm of transfected CHO cells. The percentage of CD4⁺ T cells in spleen cells in the pCMH6K/HCV-C+pGM-CSF co-vaccination group was significantly higher than those in other groups (all P < 0.05). The percentage of CD8⁺ T cells showed no significant differences among each group (P > 0.05). CTL activity induced by GM-CSF DNA co-vaccination was significantly higher than that immunized with the same amount of other naked DNA (P < 0.05). The ratio of IFN-γ to IL-4 in spleen cells from GM-CSF DNA co-vaccination group was significantly higher than those in other groups (all P < 0.05).

CONCLUSION: GM-CSF DNA could enhance the immune stimulatory effects of HCV DNA vaccine and induce Th1-type immune response.

Roles of IL-10 in ocular inflammations: a review

INTRODUCTION

This review represents the current in vitro, in vivo, animal and human investigations on the roles of IL-10 in ocular inflammatory conditions.

MATERIALS AND METHODS

The data sources were literature reviews, including Pub Med, Medline, and ISI databases (since 1989 to mid-2012). Search items were, IL-10, chemokines, cytokines, alone or in combination with, serum, aqueous, vitreous eye, ocular, ocular tissues, ophthalmic, and review.

RESULTS

Ocular effects of IL-10 depend on the sources of the secretion and sites of the action. IL-10 plays important anti-inflammatory and especially anti-angiogenic activities in ocular tissues such as the conjunctiva, cornea, retina, choroid, and orbit.

CONCLUSION

IL-10 plays major anti-inflammatory and anti-angiogenic roles in most of the ocular inflammations. Also, IL-10 plays a role in development of anterior chamber-associated immune deviation (ACAID). Any manipulation of IL-10 for treatment purposes should be considered very cautiously due to its potential hazards to the immune system.

The yin and yang of human Beta-defensins in health and disease

Rapidly evolving research examining the extended role of human beta-defensins (hBDs) in chemoattraction, innate immune-mediated response, and promotion of angiogenesis suggest that the collective effects of hBDs extend well beyond their antimicrobial mechanism(s). Indeed, the numerous basic cellular functions associated with hBDs demonstrate that these peptides have dual impact on health, as they may be advantageous under certain conditions, but potentially detrimental in others. The consequences of these functions are reflected in the overexpression of hBDs in diseases, such as psoriasis, and recently the association of hBDs with pro-tumoral signaling. The mechanisms regulating hBD response in health and disease are still being elucidated. Clearly the spectrum of function now attributed to hBD regulation identifies these molecules as important cellular regulators, whose appropriate expression is critical for proper immune surveillance; i.e., expression of hBDs in proximity to areas of cellular dysregulation may inadvertently exacerbate disease progression. Understanding the mechanism(s) that regulate contextual signaling of hBDs is an important area of concentration in our laboratories. Using a combination of immunologic, biochemical, and molecular biologic approaches, we have identified signaling pathways associated with hBD promotion of immune homeostasis and have begun to dissect the inappropriate role that beta-defensins may assume in disease.

A comprehensive review on host genetic susceptibility to human papillomavirus infection and progression to cervical cancer

Cervical cancer is the second most common cancer in women worldwide. This is caused by oncogenic types of human papillomavirus (HPV) infection. Although large numbers of young sexually active women get HPV-infected, only a small fraction develop cervical cancer. This points to different co-factors for regression of HPV infection or progression to cervical cancer. Host genetic factors play an important role in the outcome of such complex or multifactor diseases such as cervical cancer and are also known to regulate the rate of disease progression. The aim of this review is to compile the advances in the field of host genetics of cervical cancer. MEDLINE database was searched using the terms, ‘HPV’, ‘cervical’, ‘CIN’, ‘polymorphism(s)’, ‘cervical’+ *the name of the gene* and ‘HPV’+ *the name of the gene*. This review focuses on the major host genes reported to affect the progression to cervical cancer in HPV infected individuals.

Can plasma exchange therapy induce regulatory T lymphocytes in multiple sclerosis patients?

Plasma exchange is used increasingly as an individual therapeutic decision for treating of severe, steroid-resistant relapses of multiple sclerosis (MS). However, given that its mechanism of action in this CD4(+) T cell-mediated autoimmune disease remains unknown, it is not yet considered as a routine therapy for this prevalent neuroimmune disorder. In this regard, we hypothesized that plasma exchange, by depleting the body of inflammatory mediators that acts as providers of co-stimulatory signals for the adaptive immune system, provides the immune system with an exceptional break for de-novo recognition of autoantigens in a tolerogenic manner. This may lead to an increase in the frequency and function of myelin-specific regulatory T cells. For evaluating this we suggest some in vitro and in vivo studies to analyse the effects of varied dilutions of normal and MS plasmas on the induction of regulatory T cells or on the function of isolated and purified regulatory T cells. Clarifying the effects of therapeutic plasma exchange on regulatory T cells as the major controllers of autoimmune responses may provide us with strong evidence to use this procedure as a disease-modifying treatment in remission phase for reducing the rate and severity of future attacks, in addition to more trustworthy therapy in severe relapses of MS.

Identification and molecular characterization of the interleukin-10 receptor 1 of the zebrafish (Danio rerio) and the goldfish (Carassius auratus L.)

This is the first report of the identification and molecular characterization of an interleukin-10 receptor 1 in bony fish. By gene synteny analysis, we identified the zebrafish interleukin-10 receptor 1 (IL10R1) and using this IL10R1 sequence, we cloned the goldfish IL10R1 cDNA transcript. The identified fish IL10R1 protein sequences had a putative JAK1 binding site, only one of the two STAT3 binding sites, that are present in all other vertebrates IL10R1 proteins as well as C-terminal serine rich areas, believed to be responsible for the anti-inflammatory properties of IL10R1. Phylogenetically, the fish IL10R1 proteins grouped independently of the amphibian, avian and mammalian IL10R1s. Quantitative gene expression analysis of the IL10R1 of zebrafish and goldfish revealed highest mRNA levels in the spleen tissues. High mRNA levels were also observed in the zebrafish muscle in contrast to low mRNA levels in the muscle of the goldfish. Moderate IL10R1 mRNA levels were seen in most other tissues examined and lowest gene expression was in the liver of both fish species. Goldfish monocytes stimulated with a recombinant goldfish interleukin-10 (rgIL-10) or with heat killed fish pathogens, Aeromonas salmonicida or Trypanosoma carassii, exhibited significantly reduced mRNA levels of the IL10R1. Furthermore, we produced a recombinant form of the goldfish IL10R1 (rgIL10R1) and using in vitro binding studies, demonstrated that the dimerized rgIL-10 specifically interacted with rgIL10R1. Our results suggest that interleukin-10 system has been highly conserved throughout evolution.

Induction of anergic allergen-specific suppressor T cells using tolerogenic dendritic cells derived from children with allergies to house dust mites

BACKGROUND

Dendritic cells (DCs) regulate the immune response to allergens in the lung; they induce either effector or regulatory T cells, which promote or suppress, respectively, the development of allergy. IL-10 is a potent immunosuppressive cytokine that induces type 1 regulatory (Tr1) T cells.

OBJECTIVE

To generate allergen-specific Tr1 cells in vitro from children with allergy.

METHODS

Monocyte-derived DCs from children with allergy to house dust mites (HDM) were generated by incubating the cells with IL-10 and pulsing them with Der p 2, a major HDM allergen, or by pulsing them with Der p 2 and incubating them with IL-10 during their last 2 days of differentiation.

RESULTS

Der p 2-specific T-cell proliferation and T(H)2 cytokine production were significantly reduced when T cells from patients with allergy to HDM were activated with autologous Der p 2-pulsed DCs that had been differentiated or incubated with IL-10. T-cell lines generated with Der p 2-pulsed DCs that were differentiated with IL-10 were hyporesponsive to reactivation with Der p 2 and able to suppress Der p 2-specific T(H)2 effector cells.

CONCLUSION

Dendritic cells differentiated in the presence of IL-10 and pulsed with allergen gave rise to a population of tolerogenic DCs that induced allergen-specific Tr1 cells. This finding represents an important step forward to the prospective clinical application of tolerogenic DCs to modulate allergen-specific T-cell responses.

Skin application of the nonsteroidal anti-inflammatory drug ketoprofen downmodulates the antigen-presenting ability of Langerhans cells in mice

BACKGROUND

Ketoprofen (KP) is widely used as a topical nonsteroidal anti-inflammatory drug that inhibits prostaglandin (PG) biosynthesis. As PGE(2) upregulates the antigen-presenting activity of Langerhans cells (LCs), i.e. migration to lymph nodes and expression of immunocompetent molecules, modulation of LC functions resulting from topical application of KP is an issue to be clarified.

OBJECTIVES

To investigate the in vivo effect of KP application to the skin and the in vitro effect of KP addition to the culture on the antigen-presenting ability of murine LCs. Methods Ears of BALB/c mice were painted with picryl chloride (PCl) hapten, KP or both. An immunofluorescence study of epidermal sheets and a flow cytometric analysis of epidermal cell suspensions from the treated ears were performed.

RESULTS

PCl altered the morphology of LCs and reduced their number, and simultaneous application of 10% KP maintained LC morphology and number. KP at 5% or 10% clearly decreased the PCl-augmented expression of major histocompatibility complex class II and CD86 on LCs. In cultivation of freshly isolated epidermal cells, 5 mmol L(-1) KP inhibited the culture-promoted expression of these molecules on LCs, whereas 100 micromol L(-1) indomethacin was not inhibitory. The further addition of PGE(2) to the KP-containing epidermal cell culture did not restore the expression of these molecules. Moreover, topical application of 10% KP to the sensitizing sites suppressed the development of contact hypersensitivity to PCl.

CONCLUSIONS

KP may have the potential to inhibit the antigen-presenting ability of LCs, in a PGE(2)-independent manner.

Primary Nasal Epithelium Exposed to House Dust Mite Extract Shows Activated Expression in Allergic Individuals

Nasal epithelial cells form the outermost protective layer against environmental factors. However, this defense is not just physical; it has been shown that epithelial cells respond by the production of inflammatory mediators that may affect local immune responses. In this research we set out to characterize potential differences between the responses of nasal epithelium from healthy and allergic individuals to house dust mite (HDM) allergen. These differences will help us to define local mechanisms that could contribute to allergic disease expression. Epithelial cells were cultured from nasal biopsies taken from five healthy and five allergic individuals. These cultures were exposed for 24 hours to culture medium containing HDM allergen, or to culture medium alone. Isolated RNA was used for microarray analysis. Gene-ontology of the response in healthy epithelium revealed mainly up-regulation of chemokines, growth factors, and structural proteins. Moreover, we saw increased expression of two transcription factors (NF-kappaB and AP-1) and their regulatory members. The expression pattern of epithelium from allergic individuals in the absence of the HDM stimulus suggests that it is already in an activated state. Most striking is that, while the already activated NF-kappaB regulatory pathway remained unchanged in allergic epithelium, the AP-1 pathway is down-regulated upon exposure to HDM allergen; this is contrary to what we see in healthy epithelium. Clear differences in the expression pattern exist between epithelial cells isolated from healthy and allergic individuals at baseline and between their responses to allergen exposure; these differences may contribute to the inflammatory response.

Cloning and characterization of recombinant rhesus macaque IL-10/Fc(ala-ala) fusion protein: a potential adjunct for tolerance induction strategies

The powerful anti-inflammatory and immunosuppressive activities of IL-10 make it attractive for supplemental therapy in translational tolerance induction protocols. This is bolstered by reports of IL-10-mediated inhibition of innate immunity, association of human stem cell and nonhuman primate (NHP) islet allograft tolerance with elevated serum IL-10, and evidence that systemic IL-10 therapy enhanced pig islets survival in mice. IL-10 has not been examined as adjunctive immunosuppression in NHP. To enable such studies, we cloned and expressed rhesus macaque (RM) IL-10 fused to a mutated hinge region of human IgG1 Fc to generate IL-10/Fc(ala-ala). RM IL-10/Fc(ala-ala) was purified to approximately 98% homogeneity by affinity chromatography and shown to be endotoxin-free (<0.008 EU/microg protein). The biological activity of IL-10/Fc(ala-ala) was demonstrated by (1) costimulation of the mouse mast cell line, MC/9 proliferation in a dose-dependent fashion, (2) suppression of LPS-induced septic shock in mice and (3) abrogation of LPS-induced secretion of proinflammatory cytokines/chemokines in vitro and in vivo in NHP. Notably, RM IL-10/Fc(ala-ala) had significantly greater potency than human IL-10/Fc(ala-ala) and exhibited a circulating half-life of approximately 14 days. The availability of this reagent will facilitate definitive studies to determine whether supplemental therapy with RM IL-10/Fc(ala-ala) can influence tolerance outcomes in NHP.

Stimulation of Langerhans cells with ketoprofen plus UVA in murine photocontact dermatitis to ketoprofen

BACKGROUND

Ketoprofen (KP) clinically evokes the allergic type of photocontact dermatitis when applied to the skin and irradiated with ultraviolet A (UVA). We have established a murine model of photocontact dermatitis to KP, which is a T cell-mediated delayed type hypersensitivity.

OBJECTIVE

To further explore the mechanism underlying this sensitivity, we investigated whether KP plus UVA activates the antigen-presenting ability of Langerhans cells (LCs).

METHODS

We analyzed the expression of surface molecules on LCs in the murine epidermis treated with KP plus UVA by immunohistochemistry and flow cytometry. Changes in the cytokine expression of epidermal cells from KP-phototreated skin were also examined by real-time PCR.

RESULTS

LCs became larger after treatment with KP plus UVA. The number of LCs was significantly decreased 2-3 days after KP phototreatment and recovered on day 5. A flow cytometric analysis revealed that KP plus UVA increased the percentage of LCs that highly expressed MHC class II, CD86, CD80, CD54 and CD40, whereas neither KP nor UVA alone enhanced the expression. KP phototreatment augmented the expression of I-A and CD86 on LCs in KP and UVA dose-dependent manners. A real-time PCR analysis of KP-phototreated skin showed that the expression of mRNA for IL-1alpha and GM-CSF was immediately increased after treatment.

CONCLUSION

A photosensitizing regimen of KP plus UVA activates LCs at least partly by stimulating keratinocytes to produce cytokines. Two strains of mice (BALB/c and AKR) differ in responsiveness to KP and the difference is not related to the activation of keratinocytes.

Expression of the costimulatory molecule CD86, but not CD80, in keratinocytes of normal cervical epithelium and human papillomavirus-16 positive low squamous intraepithelial lesions

Keratinocytes have been traditionally considered as nonprofessional antigen presenting cells, since multipassaged cells from skin biopsies of healthy individuals do not constitutively express major histocompatibility complex (MHC) class II or costimulatory molecules, but can be induced to do so after exposure to interferon-gamma. In normal and human papillomavirus (HPV)-infected cervical epithelium, keratinocytes are affected by a variety of soluble mediators that could modulate the expression of molecules including costimulatory proteins; however, the presence of these molecules within the cervix has been poorly studied. Therefore, our aim was to further explore the presence of costimulatory molecules on normal cervical epithelium and HPV-16 positive low squamous intraepithelial lesions (LSIL). We found in situ CD86 (but not CD80) displayed on the surface of normal keratinocytes from the spinous layer of human cervical epithelium. The presence of the protein and its messenger RNA level (evaluated by in situ hybridization) was diminished in HPV-16 positive LSILs. Although downregulation of costimulatory molecules is frequently related to cytokines expression, we did not observe differences in the presence of interleukin-10, the main cytokine that inhibits CD86 expression. Expression of CD86 on keratinocytes from normal cervical epithelium could indicate the potentiality of these cells to activate cytotoxic T cells, while the shut-off of this molecule in HPV-16 positive lesions could be a mechanism for evading host immune surveillance, resulting in the persistent HPV infection and probable progression of cervical lesions.

Expression of constitutively active STAT3 can replicate the cytokine-suppressive activity of interleukin-10 in human primary macrophages

There is general agreement that signal transducer and activation of transcription 3 (STAT3) is required to mediate the anti-inflammatory activities of interleukin (IL)-10. However, STAT3 is activated by multiple factors that do not share the anti-inflammatory activity of IL-10. The question remains whether STAT3 is sufficient for the anti-inflammatory effects or whether there are other signals required, as had been suggested previously. We set out to map the human IL-10 receptor and to identify the key elements involved in transducing the cytokine-suppressive effects of IL-10. We were able to show an absolute requirement for both of the tyrosine residues found within the YXXQ-STAT3-docking site within the IL-10 receptor 1 and that no other signals appeared to be required. We used a constitutively active STAT3 to determine whether expression of this factor could suppress lipopolysaccharide-induced tumor necrosis factor and IL-6 production. Our data show that STAT3 activity can suppress both IL-6 and tumor necrosis factor production in lipopolysaccharide-stimulated macrophages. However, in synovial fibroblasts, STAT3 did not suppress IL-6 production, suggesting that the cellular environment plays an important role in dictating whether STAT3 drives a pro- or anti-inflammatory response.

Intramuscular immunization with a monogenic plasmid DNA tuberculosis vaccine: Enhanced immunogenicity by electroporation and co-expression of GM-CSF transgene

Plasmid DNA vaccine has been widely explored for tuberculosis immunization but there is a need to develop the ways to improve its immunogenicity. In this study, we have constructed a plasmid DNA vaccine coding for Ag85A alone or for both Ag85A and GM-CSF and investigated the immune adjuvant effects of electroporation and GM-CSF co-expression, alone or in combination, on CD4 and CD8 T cell IFN-gamma responses, CTL activities and immune protection from pulmonary Mycobacterium tuberculosis challenge in a Balb/c mouse model. We have found that use of electroporation allows a single intramuscular (i.m.) DNA injection to be as effective as repeated i.m. DNA injections in activation of both Ag85A-specific CD4 and CD8 T cells. Co-expression of immune-enhancing cytokine GM-CSF by the same plasmid DNA TB vaccine could further enhance T cell activation including CTL activities on top of electroporation. With regard to immune protection from pulmonary M. tb challenge, use of electroporation also allows a single i.m. DNA injection to be as effective as repeated i.m. DNA injections. Co-expression of GM-CSF transgene also moderately enhances immune protection and such effect is more evident for systemic protection. However, GM-CSF expression has little added effect on immune protection by electroporation-aided immunization protocols. Our findings thus will help with the development of future DNA TB immunization strategies.

Dendritic cells: key cells for the induction of regulatory T cells?

Even though dendritic cells (DCs) are well known for their capacity to induce immune responses, recent results show that they are also involved in the induction of tolerance. These two contrary effects of otherwise homologous DCs on a developing immune response maybe explainedby different DC developmental stages, i.e., different subsets of DCs may exist and/or different spatial distribution of DCs in the body might influence their function. However, independently from the subtype(s), it is obvious that the ability of DCs to act in a tolerogenic fashion depends on the maturation status, since immature DCs are prone to induce regulatory T cells and hence promote tolerance, whereas mature DCs stimulate effector T cells, facilitating immunity. The means by which DCs convey tolerance are not entirely clear yet, but secretion of suppressive cytokines such as IL-10 and induction of regulatory lymphocytes are involved. In this review we focus on the interaction between DCs and T cells and highlight some mechanisms in the decision-making process of whether immunity or tolerance is induced.

Interleukin-10 and Fas polymorphisms and susceptibility for (pre)neoplastic cervical disease

Infection with oncogenic types of human papillomavirus (HPV) is the main causal factor of cervical cancer and its precursor lesion (cervical intraepithelial neoplasia [CIN]). Cellular immunity may be critical in the elimination of HPV-harboring cells. Interleukin-10, a T-helper type 2 cytokine, has a suppressive effect on cell-mediated immunity. Resistance to apoptosis through the Fas pathway might enable many cancers to escape the immune system. We examined in a large study population whether three polymorphisms in the IL-10 gene and a polymorphism at position -670 of the Fas promotor affect susceptibility for cervical cancer or its precursor. In addition, it was studied whether these polymorphisms were causal and not merely associated by typing microsatellite markers in the region surrounding both genes. A total of 311 CIN, 695 cervical cancer patients, and 115 family-based and 586 unrelated controls were analyzed. Association analysis revealed an increased CIN (II-III) (OR 1.44 [1.06-1.97]) and squamous cell carcinoma of the cervix (OR 1.35 [1.04-1.75]) for individuals heterozygous for the A-allele of the IL-10-592 polymorphism. In contrast to previous findings, no association was found for the IL-10-1082 polymorphism. While an increased risk for adenocarcinoma (AC) in heterozygotes (OR 1.59 [1.02-2.48]) was observed. Our study shows a possible role for the IL-10 gene in CIN and squamous cell cervical cancer susceptibility in the Caucasian population; simultaneously, there might be a role for the Fas gene in the development of AC of the cervix. Further investigations with a higher density of markers are necessary to find the causal mutation.

Immunoregulatory effects of regulated, lung-targeted expression of IL-10 in vivo

Regulation of pulmonary inflammation involves an intricate balance of both pro- and anti-inflammatory mediators. Acute lung injury can result from direct pulmonary insults that activate alveolar macrophages to respond with increased cytokine expression. Such cytokine gene expression is mediated in part via NF-κB. IL-10 has been previously identified as an important endogenous anti-inflammatory cytokine in vivo on the basis of inhibiting NF-κB activation; however, the mechanism of this inhibition remains incompletely defined. We hypothesized that IL-10 regulated NF-κB activation in vivo via IκK inhibition. A bitransgenic mouse that allowed for externally regulated, lung-specific human IL-10 overexpression was generated. In the bitransgenic mice, introduction of doxycycline induced lung-specific, human IL-10 overexpression. Acute induction of IL-10 resulted in significant decreases in bronchoalveolar lavage fluid neutrophils (48%, P = 0.03) and TNF (62%, P < 0.01) following intratracheal LPS compared with bitransgenic negative mice. In vitro kinase assays showed this decrease to correlate to diminished lung IκK activity. Furthermore, we also examined the effect of chronic IL-10 overexpression in these transgenic mice. Results show that IL-10 overexpression in lungs of mature mice increased the number of intrapulmonary cells the phenotype of which was skewed toward increased B220+/CD45+ B cells and CD4+ T cells and was associated with increased CC chemokine expression. Thus regulated, lung-specific IL-10 overexpression may have a variety of complex immunologic effects depending on the timing and duration of expression.

Topical application of culture supernatant from human amniotic epithelial cells suppresses inflammatory reactions in cornea

Human amniotic epithelial cells (HAEC) may be a source of soluble anti-inflammatory factors. The purpose of this study is to determine the effect of topically applied HAEC culture supernatant on corneal inflammatory reactions. HAEC were obtained from a placenta and cultured for 48 hr, and the supernatant was collected. The conditioned medium from HAEC contained small amounts of human interleukin-1 receptor antagonist (IL-1ra). Intrastromal sutures were placed in the cornea of BALB/c mice to induce corneal neovascularisation. Superficial cauterisation was applied to induce recruitment or activation of antigen presenting cells (APCs) in the cornea without neovascularisation. HAEC conditioned medium, placebo, or recombinant human IL-1ra was topically applied three times daily for 2 weeks. Suture-induced corneal neovascularisation was evaluated microscopically for 8 weeks. The cauterised corneas were harvested at 2 weeks, and the MHC class II(+) APCs were quantified by immunofluorescent staining and confocal microscopy. Inflammatory cytokine gene expression in the cauterised corneas was analyzed by a multiprobe ribonuclease protection assay. Conditioned medium from HAEC led to a profound suppression of corneal neovascularisation and fewer MHC class II(+) APCs in the epithelium. In contrast, human IL-1ra was only slightly effective in suppressing corneal inflammatory reactions. mRNA expression of murine IL-1ra and IL-1beta in the cauterised corneas was markedly suppressed after application of the conditioned medium. These results suggest that HAEC are a source of soluble anti-inflammatory factors and that conditioned medium from HAEC contains factors other than IL-1ra that suppress corneal inflammation.

Metastatic melanoma secreted IL-10 down-regulates CD1 molecules on dendritic cells in metastatic tumor lesions

CD1 molecules are expressed by antigen-presenting cells such as dendritic cells and mediate primary immune responses to lipids and glycolipids which have been shown to be expressed by various tumors. Glycolipids are expressed by melanoma cells but, despite their immunogenicity, no efficient spontaneous immune responses are elicited. As IL-10 has previously been shown to down-regulate CD1a on dendritic cells and is known to be expressed by various melanoma cell lines, we investigated if melanoma-derived IL-10 could down-regulate CD1 molecule expression on dendritic cells as a possible way to circumvent immune recognition. We found that CD1a, CD1b, CD1c, and CD1d were significantly down-regulated on dendritic cells in metastatic (n = 10) but not in primary melanoma lesions (n = 10). We further detected significantly higher IL-10 protein levels in metastatic than in primary melanomas. Moreover, supernatants from metastatic melanomas were significantly more effective in down-regulating CD1 molecules on dendritic cells than supernatants from primary melanoma cultures. This effect was blocked using a neutralizing IL-10 antibody in a dose dependent manner. Our findings suggest that metastatic but not primary melanomas can down-regulate CD1 molecules on infiltrating dendritic cells by secreting IL-10 which may represent a novel way to escape the immune response directed against the tumor.

Interleukin-10 suppression of myeloid cell activation--a continuing puzzle

Efforts to identify the signal transduction pathways used by interleukin-10 (IL-10) have resulted in limited success. The anti-inflammatory effects elicited by IL-10, and the mechanisms by which these are mediated, are still relatively unknown. Understanding the signalling mechanisms behind the suppression of cytokine expression by IL-10 could be of potential therapeutic interest. Although the consensus is that the Janus kinase, Jak1, as well as the signal transducer and activator of transcription STAT3 are central, much controversy exists about the participation and roles of many other signalling pathways targeted by IL-10. The mechanisms of cytokine suppression proposed by various groups have included transcriptional, post-transcriptional and post-translational regulation of IL-10 target genes; nevertheless no unifying model has emerged thus far. Here we would like to highlight novel findings and discuss their implications in the context of current understanding of IL-10 signalling.

Protective potential of experimental autoimmune myasthenia gravis in Lewis rats by IL-10-modified dendritic cells

Dendritic cells (DC) are usually regarded as antigen-presenting cells (APC) involved in T cell activation, but DC also directly or indirectly affect B cell function, antibody synthesis and isotype switch. In this study, we explore potential of DC-based immunotherapy in ongoing experimental autoimmune myasthenia gravis (EAMG) in Lewis rats, which is mediated by anti-acetylcholine receptor (AChR) antibodies. Spleen DC were isolated from onset of Lewis rat EAMG on day 39 post immunization (p.i.), exposed in vitro to IL-10 and then injected intraperitoneally into ongoing EAMG Lewis rats at dose of 1 x 10(6) cells/rat on day 5 p.i. with AChR + complete Freund's adjuvant. IL-10-modified DC resulted in lower clinical scores, less body weight loss, lower numbers of anti-AChR IgG antibody-secreting cells and lower affinity of anti-AChR antibodies in rats receiving IL-10-modified DC, accompanied with lower expression of CD80 and CD86 and lower lymphocyte proliferation among lymph node mononuclear cells compared with control EAMG rats. Lower levels of IL-10 and IFN-gamma were also found in the supernatants of AChR-stimulated lymph node MNC culture in rats receiving IL-10-modified DC. These results demonstrate that IL-10-modified DC induced hypo-responsiveness by down-regulating co-stimulatory molecules, and reduced production of anti-AChR antibodies possibly by inhibiting IL-10 production. Importantly, this procedure that autologous DC from EAMG were adopted to treat ongoing EAMG is more close to clinical trial in human, encouraging future evaluation in human myasthenia gravis.

T-cell costimulatory capacity of oral and skin epithelial cells in vitro: presence of suppressive activity in supernatants from skin epithelial cell cultures

Oral Langerhans cells (LC) have better T-cell costimulatory capacity than skin LC. In this study factors affecting this capacity have been assessed in a mixed epithelial cell lymphocyte reaction (MELR) assay. Flow cytometry analysis of freshly recovered cells revealed major histocompatibility complex (MHC) class II molecule expression on 7.5% of the oral epithelial cells and 9.7% of the skin epithelial cells. Monoclonal anti class II antibodies significantly reduced the T-cell proliferation in the MELR. Pretreatment of skin epithelial cells with interleukin-1beta, tumour necrosis factor-alpha or interferon (IFN)-gamma did not affect the MELR proliferation, but incubation with IFNgamma significantly suppressed the T-cell response. Transfer of supernatants from cultures of skin epithelial cells and allogeneic T cells to cultures of oral epithelial cells and T cells resulted in a reduced T-cell proliferation while supernatants from oral epithelial cells and T cells did not reduce proliferation. The higher proliferation in cultures of T cells and oral epithelial cells than in cultures containing skin epithelial cells may be due to the presence of a suppressive factor in the skin epithelial cell suspensions.

Signal transducer and activator of transcription 3 is the dominant mediator of the anti-inflammatory effects of IL-10 in human macrophages

The signaling mechanism by which the anti-inflammatory cytokine IL-10 mediates suppression of proinflammatory cytokine synthesis remains largely unknown. Macrophage-specific STAT3-null mice have demonstrated that STAT3 plays a critical role in the suppression of LPS-induced TNF-alpha release, although the mechanism by which STAT3 mediates this inhibition is still not clear. Using an adenoviral system, we have expressed a dominant negative (DN) STAT3 in human macrophages to broaden the investigation to determine the role of STAT3 in IL-10-mediated anti-inflammatory signaling and gene expression. Overexpression of STAT3 DN completely inhibited IL-10-induced suppressor of cytokine signaling 3, tissue inhibitor of MMP-1, TNF receptor expression, and the recently identified IL-10-inducible genes, T cell protein tyrosine phosphatase and signaling lymphocyte activation molecule. STAT3 DN also blocked IL-10-mediated inhibition of MHC class II and COX2 expression. In agreement with the studies in STAT3-null mice, overexpression of the STAT3 DN completely reversed the ability of IL-10 to inhibit LPS-mediated TNF-alpha and IL-6 production. However, real-time PCR analysis showed that STAT3 DN expression did not affect immediate suppression of TNF-alpha mRNA, but did reverse the suppression observed at later time points, suggesting a biphasic regulation of TNF-alpha mRNA levels by IL-10. In conclusion, although STAT3 does appear to be the dominant mediator of the majority of IL-10 functions, there are elements of its anti-inflammatory activity that are STAT3 independent.

Differential Expression and Function of Toll-like Receptors in Langerhans Cells: Comparison with Splenic Dendritic Cells

Toll-like receptors are key elements in pathogen recognition by the host immune system. Although the expression pattern and functions of Toll-like receptors have been studied in a variety of cytokine-induced dendritic cells, it remains unknown whether Toll-like receptor stimulation influences maturation and cytokine production of authentic Langerhans cells. We purified murine epidermal Langerhans cells along with splenic dendritic cell using a panning method. Langerhans cells expressed Toll-like receptor 2, 4, and 9 but not 7, the pattern of which suggests Langerhans cells are the closest to one of the murine dendritic cell lineage, CD11c+11b+8 alpha-4-. Then we stimulated Toll-like receptor 2, 4, and 9 with the corresponding ligand, Staphylococcus aureus Cowan 1, lipopolysaccharide, and CpG, and found that all of these stimuli upregulated expression of B7-1 and B7-2 in splenic dendritic cells but not in Langerhans cells. As in human Langerhans cells, stimulation of murine Langerhans cells with Staphylococcus aureus Cowan 1, lipopolysaccharide, and CpG overall resulted in T helper 1-polarizing cytokine production (namely, induction of IL-12p40 and inhibition of TARC (thymus and activation-regulated chemokine)/CCL17). Exceptionally, lipopolysaccharide exhibited no effect on IL-12p40 production by Langerhans cells and inhibited IL-12p40 production by splenic dendritic cells. These results may represent the functional heterogeneity between Langerhans cells and splenic dendritic cells, and are important for better understanding of innate immunity to bacterial infections differentially regulated in the skin and spleen. MeSH terms: Toll-like receptors, Langerhans cells, dendritic cells.

Paradoxical effects of interleukin-10 on the maturation of murine myeloid dendritic cells

The immunoregulatory cytokine, interleukin-10 (IL-10), has been shown to inhibit the maturation of human myeloid dendritic cells (DC). In the present study, we demonstrate that IL-10 has paradoxical effects on the maturation of murine myeloid bone marrow-derived DC. On the one hand, IL-10 inhibits the maturation of murine myeloid DC. The addition of IL-10 to granulocyte-macrophage colony-stimulating factor (GM-CSF)-supported murine BM-derived DC cultures reduced the frequency of major histocompatibility complex (MHC) class IIbright cells. These IL-10-pretreated DC have a reduced capacity to stimulate T cells in an allogeneic mixed leucocyte reaction. On the other hand, however, and in contrast to the effects of IL-10 on human DC, we found that the addition of IL-10 from the initiation of the culture onwards induced an up-regulation of the expression of the costimulatory molecules CD40, CD80 and CD86 on murine myeloid DC, as compared to DC generated with GM-CSF only. Moreover, a subpopulation of IL-10-pretreated MHC class IIdim DC lacked the capacity to take up dextran-fluorescein isothiocyanate (FITC), a feature of DC maturation. Taken together, our data demonstrate that the generation of murine myeloid DC in the presence of IL-10 results in a population of incompletely matured MHC class IIdim CD80+ CD86+ DC. These DC lack T-cell stimulatory capacity, suggesting a role for IL-10 in conferring tolerogenic properties on murine myeloid DC.

Altered cutaneous immune parameters in transgenic mice overexpressing viral IL-10 in the epidermis

IL-10 is a pleiotropic cytokine that inhibits several immune parameters, including Th1 cell-mediated immune responses, antigen presentation, and antigen-specific T cell proliferation. Recent data implicate IL-10 as a mediator of suppression of cell-mediated immunity induced by exposure to UVB radiation (280-320 nm). To investigate the effects of IL-10 on the cutaneous immune system, we engineered transgenic mice that overexpress viral IL-10 (vIL-10) in the epidermis. vIL-10 transgenic mice demonstrated a reduced number of I-A(+) epidermal and dermal cells and fewer I-A(+) hapten-bearing cells in regional lymph nodes after hapten painting of the skin. Reduced CD80 and CD86 expression by I-A(+) epidermal cells was also observed. vIL-10 transgenic mice demonstrated a smaller delayed-type hypersensitivity response to allogeneic cells upon challenge but had normal contact hypersensitivity to an epicutaneously applied hapten. Fresh epidermal cells from vIL-10 transgenic mice showed a decreased ability to stimulate allogeneic T cell proliferation, as did splenocytes. Additionally, chronic exposure of mice to UVB radiation led to the development of fewer skin tumors in vIL-10 mice than in WT controls, and vIL-10 transgenic mice had increased splenic NK cell activity against YAC-1targets. These findings support the concept that IL-10 is an important regulator of cutaneous immune function.

Granulocyte-macrophage colony stimulating factor is an anti-apoptotic cytokine for thymic dendritic cells and a significant modulator of their accessory function

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a growth-promoting factor for myeloid-derived dendritic cells (DC) but not for lymphoid DC. The data about its effect on thymic DC (TDC), which are both of lymphoid and myeloid origin, are very scarce. Using an in vitro model, we demonstrated in this work that GM-CSF significantly increased the survival of rat TDC in culture by inhibiting their apoptosis and the effect correlated with up-regulation of Bcl-2 expression. GM-CSF also stimulated differentiation and maturation of TDC as judged by higher expression of MHC class I and II molecules, CD54, CD80 and CD86. These changes correlated with stronger stimulatory activity of GM-CSF-pulsed TDC in syngeneic thymocyte proliferation assay and MLR. The stimulatory potential of TDC was further increased when thymocytes were cultivated with an anti-alphabeta TCR (R73) monoclonal antibody (mAb). The influence of unstimulated TDC on proliferation of thymocytes was inhibited by anti-CD86 but not anti-CD80 mAb, whereas in cultures with GM-CSF-treated TDC both mAbs exerted an additive blocking effect. After separation of TDC on CD11b(+) and CD11b(-) we demonstrated that GM-CSF inhibited apoptosis and potentiated accessory activity of both TDC subsets independently of the myeloid marker expression. Cummulatively, our results suggest that GM-CSF is one of the regulatory cytokine involved in survival, maturation, differentiation and accessory function of TDC.

Development of CD4+ T cell lines that suppress an antigen-specific immune response in vivo

It has been suggested for many years that the regulation of the immune system for the maintenance of peripheral tolerance may involve regulatory/suppressor T cells. In the past few years, several investigators have demonstrated that these cells can be generated in vitro. It has also been shown that they can inhibit the progression of various autoimmune disease models when infused into susceptible mice. We have generated two murine T cell lines in the presence of KLH-specific T cell clones from BALB/c or DBA2 mice. The lines are characterized by a low proliferative response to mitogens, the capacity to secrete high amounts of IL-10 and TGF-beta, and small amounts of IFN-gamma. Interestingly, these cells are unable to produce IL-2, IL-4 or IL-5. The study of the surface phenotype of both lines revealed CD4+, CD25high, CD44low and CTLA-4- cells. When injected intravenously in (CBy.D2) F1 mice, these cells were able to inhibit 50-100% of the TNP-specific antibody production, when the hapten was coupled to KLH. In the present study we offer another evidence for the existence of regulatory T cells in the T lymphocyte repertoire, suggesting that they can also regulate immune responses to foreign antigens. Furthermore, we demonstrate an alternative pathway to generate these cells different from approaches used thus far.

Surfactant protein A modulates the differentiation of murine bone marrow-derived dendritic cells

Surfactant protein A (SP-A) is an innate immune molecule that regulates pathogen clearance and lung inflammation. SP-A modulates innate immune functions such as phagocytosis, cytokine production, and chemotaxis; however, little is known about regulation of adaptive immunity by SP-A. Dendritic cells (DCs) are the most potent antigen-presenting cell with the unique capacity to activate naive T cells and initiate adaptive immunity. The goal of this study was to test the hypothesis that SP-A regulates the differentiation of immature DCs into potent T cell stimulators. The data show that incubation of immature DCs for 24 h with SP-A inhibits basal- and LPS-mediated expression of major histocompatibility complex class II and CD86. Stimulation of immature DCs by SP-A also inhibits the allostimulation of T cells, enhances dextran endocytosis, and alters DC chemotaxis toward RANTES and secondary lymphoid tissue chemokine. The effects on DC phenotype and function are similar for the structurally homologous C1q, but not for SP-D. These studies demonstrate that SP-A participates in the adaptive immune response by modulating important immune functions of DCs.

Chronic exposure to innocuous antigen in sensitized mice leads to suppressed airway eosinophilia that is reversed by granulocyte macrophage colony-stimulating factor

In this study we investigated the impact of chronic allergen exposure on airway inflammation and humoral responses in sensitized mice. We observed marked eosinophilia in the bronchoalveolar lavage, lung tissue, and peripheral blood after 2 wk of exposure. In contrast, eosinophilia was markedly reduced by 3 wk and completely resolved by 4 wk of exposure, despite the continued presence of Ag. Decreases in airway eosinophilia were associated with a robust humoral response. We observed that levels of OVA-specific IgE, IgG1, and IgG2a increased during the course of exposure. To assess whether continuous exposure to Ag impacts the ability of the lung to respond to subsequent Ag challenge, mice were exposed to either 2 or 4 wk of OVA in the context of GM-CSF. All groups were then rested for 28 days and exposed to OVA on three consecutive days. We observed a significant decrease in airway eosinophilia and IL-5 expression in the bronchoalveolar lavage and serum in mice initially exposed to 4 wk of OVA, compared with animals exposed to 2 wk only. However, in both groups expression of B7.2 on dendritic cells as well as CD25, CD69, and T1/ST2 on CD4(+) T cells was enhanced, suggesting immune activation. Delivery of rGM-CSF fully restored airway eosinophilia. This study shows that exposure to innocuous Ag alone does not lead to persistent eosinophilic airway inflammation, but rather to abrogated eosinophilia. This suppression can be reversed by GM-CSF.

Genetic polymorphisms influencing therapy and susceptibility to rejection in organ allograft recipients

Solid organ transplantation during the past 30 years has developed from an experimental procedure into routine clinical practice. The current repertoire of immunosuppressive agents has made a major contribution to transplant survival; however, problems in different areas still need to be overcome. Several gene polymorphisms are supposed to influence immunosuppressive therapy and susceptibility to rejection. Therefore, a priority of transplant biologists is to estimate individual patient risk and to characterise the genetic profile of patients in need of a transplant in order to optimise the use of a scarce resource such as organs from cadaver donors, and to avoid serious drug-induced adverse effects. Polymorphisms in genes encoding tumour necrosis factor-alpha (TNFalpha), interleukin (IL)-6, IL-10, interferon-gamma (IFNgamma), transforming growth factor-beta (TGFbeta) and thiopurine S-methyltransferase (TPMT) can have significant effects on an individual's risk of rejection, as well as their ability to tolerate immunosuppressive therapy. Genotyping of known polymorphisms in these genes may in the future contribute to our ability to individualise immunosuppressive therapy in organ transplant recipients.

Irradiation up-regulates CD80 expression through induction of tumour necrosis factor-alpha and CD40 ligand expression on B lymphoma cells

Previously, we reported that 100 Gy X-ray irradiation followed by 24 hr incubation up-regulates CD80 expression in murine B lymphoma cells, A20-2J. In the present study, we analysed the underlying mechanisms of such up-regulation using A20-HL cells derived from A20-2J cells. Irradiation of A20-HL cells with 100 Gy enhanced CD80 expression. Incubation of untreated A20-HL cells with those 100 Gy irradiated induced up-regulation of CD80 expression. Irradiation of A20-HL cells also up-regulated the expression of tumour necrosis factor-alpha (TNF-alpha) and CD40 ligand (CD40L), and the amount of immunoprecipitable TNF-alpha and CD40L in cell lysates. The addition of anti-TNF-alpha or anti-CD40L monoclonal antibody (mAb) to the incubation of irradiated A20-HL cells partially inhibited up-regulation of CD80 expression, and the addition of both antibodies together almost completely inhibited the up-regulation, suggesting that irradiation up-regulated the CD80 expression through the induction of TNF-alpha and CD40L expression. Irradiation also increased the accumulation of CD80, TNF-alpha and CD40L mRNA. n-tosyl-l-phenylalanine chloromethyl ketone (TPCK), a nuclear factor (NF)-kappaB inhibitor, markedly decreased irradiation-induced accumulation of CD80 mRNA and CD80 expression. FK506, a calcineurin inhibitor, and nifedipine, a calcium channel inhibitor, inhibited not only the expression of TNF-alpha and CD40L, but also the up-regulation of CD80 on irradiated A20-HL cells. These results strongly suggested that irradiation induced TNF-alpha and CD40L expression, which then up-regulated CD80 mRNA and CD80 expression through activation of NF-kappaB transcription factor in A20-HL cells.

CD4(+) and CD8(+) anergic T cells induced by interleukin-10-treated human dendritic cells display antigen-specific suppressor activity

Interleukin-10 (IL-10)-treated dendritic cells (DCs) induce an alloantigen- or peptide-specific anergy in various CD4(+) and CD8(+) T-cell populations. In the present study, we analyzed whether these anergic T cells are able to regulate antigen-specific immunity. Coculture experiments revealed that alloantigen-specific anergic CD4(+) and CD8(+) T cells suppressed proliferation of syngeneic T cells in a dose-dependent manner. The same effect was observed when the hemagglutinin-specific CD4(+) T-cell clone HA1.7 or tyrosinase-specific CD8(+) T cells were cocultured with anergic T cells of the same specificity. Anergic T cells did not induce an antigen-independent bystander inhibition. Suppression was dependent on cell-to-cell contact between anergic and responder T cells, required activation by antigen-loaded DCs, and was not mediated by supernatants of anergic T cells. Furthermore, anergic T cells displayed an increased extracellular and intracellular expression of cytotoxic T-lymphocyte antigen (CTLA)-4 molecules, and blocking of the CTLA-4 pathway restored the T-cell proliferation up to 70%, indicating an important role of the CTLA-4 molecule in the suppressor activity of anergic T cells. Taken together, our experiments demonstrate that anergic T cells induced by IL-10-treated DCs are able to suppress activation and function of T cells in an antigen-specific manner. Induction of anergic T cells might be exploited therapeutically for suppression of cellular immune responses in allergic or autoimmune diseases with identified (auto) antigens.

Decreased lamina propria effector cell responsiveness to interleukin-10 in ileal Crohn's disease

We investigated whether a lack of IL-10 production or responsiveness could be involved in Crohn's disease pathogenesis. Lamina propria mononuclear cells, isolated from the ilea of Crohn's disease patients (n = 16) and controls (n = 13), were activated with anti-CD3 mAb in the presence of CD80 transfectants or LPS +/- IFN-gamma. No evidence for deficient IL-10 production by either T cells or macrophages in Crohn's disease was found. However, the efficacy of rhIL-10 to down-regulate IFN-gamma and especially TNF production in cell cultures from the involved tissues of Crohn's disease patients was poor, and the use of an anti-IL-10R mAb even provided evidence for proinflammatory effects of IL-10. This lack of IL-10 effect possibly results from IL-12 activity. We conclude that IL-10 exhibits poor anti- and even potential proinflammatory effects on ileal Crohn's disease lamina propria. These data might explain the lack of therapeutic efficacy when IL-10 is given to Crohn's disease patients.

Dissociation of innate and adaptive immunity by UVB irradiation

Increasing ultraviolet-B irradiation (UVB) resulting from diminution of stratospheric ozone is becoming a serious international problem. UVB irradiation exerts not only carcinogenic effects on animals but also causes them to become vulnerable to infections by modulating their immune responses. UVB irradiation suppresses innate immune functions of cells such as macrophages, neutrophils, Langerhans cells, dendritic cells, and the serum component, complement. UVB irradiation also causes changes in cytokine profiles, represented by the induction of a paradigm switch involving Th1/Th2 phenotypes. According to earlier studies, Th1 responses are suppressed, whereas Th2 activities are augmented by UVB irradiation. These immune modulations are caused by several pathways via cytokines and neuropeptides, and eventually may lead to increasing incidences of infection, allergy, and cancer. We have reviewed reports concerning UVB-irradiation induced immune modulation from the viewpoint of risks for human diseases and, in addition, for ecosystems and immunity of lower animals.

Cancer of the uterine cervix may be significantly associated with a gene polymorphism coding for increased IL-10 production

The purpose of our prospective, case-controlled study was to investigate the hypothesis that women who are genetically programmed to produce high or medium levels of IL-10 were more likely to develop cancer of the uterine cervix than individuals genetically predisposed to low IL-10 production. The population was recruited from patients attending gynecological clinics at 2 hospitals in Harare, Zimbabwe. Laboratory tests were performed in the Departments of Immunology, Chemical Pathology and Medical Microbiology, Medical School, University of Zimbabwe, and simultaneously at the Department of Biological Sciences, University of Manchester, United Kingdom. Included in our study were 77 women with histologically proven cancer of the uterine cervix and 69 age- and parity-matched healthy women. All of the patients and healthy controls were from the Shona ethnic group that inhabits northern Zimbabwe. DNA was purified from cervical cytobrush samples obtained from women with cervical cancer. Control DNA was extracted from urine or peripheral blood samples from the healthy women. The Qiagen DNA extraction kit was used. Detection of allele A and/or G at -1082 in the promoter region of the IL-10 gene was carried out using the ARMS-PCR technique. Polymorphism in the amplified products was detected by gel electrophoresis in the presence of ethidium bromide and were bands visualized under UV light. The data comprise 77 women who developed invasive cervical cancer and 69 healthy women matched for age and parity. Patients with cancer were significantly (p = 0.001) more likely to be predisposed to produce higher (A/G) levels of IL-10. The genotype encoding for high (G/G) production of IL-10 was only observed in one cancer patient. The prevalence of low producers of IL-10 in the cancer group was significantly lower than in the healthy women. There were no high producers amongst the healthy women. These data suggest that the genetically acquired ability to produce higher levels of IL-10 may be a significant factor in the development of cervical cancer.