Increase IL-4 Production Research Articles

Monocyte (THP-1) Response to Silver Nanoparticles Synthesized with Rumex hymenosepalus Root Extract.

The study, synthesis, and application of nanomaterials in medicine have grown exponentially in recent years. An example of this is the understanding of how nanomaterials activate or regulate the immune system, particularly macrophages. In this work, nanoparticles were synthesized using Rumex hymenosepalus as a reducing agent (AgRhNPs). According to thermogravimetric analysis, the metal content of nanoparticles is 55.5% by weight. The size of the particles ranges from 5-26 nm, with an average of 11 nm, and they possess an fcc crystalline structure. The presence of extract molecules on the nanomaterial was confirmed by UV-Vis and FTIR. It was found by UPLC-qTOF that the most abundant compounds in Rh extract are flavonols, flavones, isoflavones, chalcones, and anthocyanidins. The viability and apoptosis of the THP-1 cell line were evaluated for AgRhNPs, commercial nanoparticles (AgCNPs), and Rh extract. The results indicate a minimal cytotoxic and apoptotic effect at a concentration of 12.5 μg/mL for both nanoparticles and 25 μg/mL for Rh extract. The interaction of the THP-1 cell line and treatments was used to evaluate the polarization of monocyte subsets in conjunction with an evaluation of CCR2, Tie-2, and Arg-1 expression. The AgRhNPs nanoparticles and Rh extract neither exhibited cytotoxicity in the THP-1 monocyte cell line. Additionally, the treatments mentioned above exhibited anti-inflammatory effects by maintaining the classical monocyte phenotype CD14++CD16, reducing pro-inflammatory interleukin IL-6 production, and increasing IL-4 production.

Fasciola hepatica fatty acid binding protein (Fh12) induces apoptosis and tolerogenic properties in murine bone marrow derived dendritic cells

In a previous study we demonstrated that Fasciola hepatica fatty acid binding protein (Fh12) significantly suppress macrophage function by inhibiting IL-6, IL-1β, tumor necrosis factor (TNF)-α and IL-12 production in TLR4-stimulated murine macrophages, an effect mediated through the signaling of CD14 co-receptor without affecting the viability of these cells. Given that dendritic cells (DCs) are immune cells that play a central role in the initiation of primary immune responses and that are the only antigen-presenting cells capable of stimulating naïve T-cells, in the present study we investigated the effect of Fh12 on DCs. We found that Fh12 exerts a strong suppressive effect on activation and function of DCs. However, in contrast to the effect observed on macrophages, Fh12 induces early and late apoptosis of DCs being this phenomenon dose-dependent and CD14-coreceptor independent. At low concentration Fh12 modulates the LPS-induced DCs maturation status by suppressing the MHC-II, and co-stimulatory molecules CD40 and CD80 surface expression together with the pro-inflammatory cytokines IL-12p70 and IL-6 production whereas increase the IL-10 levels. Besides, Fh12 decreased the ability of LPS-activated DCs to induce IFN-γ production against allogeneic splenocytes, while increasing IL-4 production. We have described for the first time the ability of Fh12 to modify selectively the viability of DCs by apoptosis induction. The selective diminution in DCs survival could be a F. hepatica strategy in order to prevent a host immune response during the earliest phases of infection.

Immuno-profiles of BALB/c mice inoculated with Salmonella vector delivering B-cell mitogen hydroxyproline epimerase

The enzyme 4-hydroxyproline 2-epimerase (PrpA) involves in modulation of host immunity and is also reported as a potent B-cell mitogen. Live attenuated Salmonella Typhimurium (ST) vector constitutively expressing heterologous Brucella abortus PrpA protein (ST-PrpA) was inoculated in BALB/c mice in order to investigate the influence of the enzyme, on safety aspects, humoral and cellular immunity as well as protective efficacies against wild type challenges. No aggravation of morbidity was observed upon mice inoculation of ST-PrpA. Immunized mice showed significantly quicker anti-Salmonella IgG responses as compared to ST only immunization. This finding is in congruency with the increase IL-4 production evident in in vitro pulsed mice splenocytes. Increase protection against Salmonella challenge was also observed. These findings suggest that PrpA can be used as a protein adjuvant in a live Salmonella delivery system, in order to increase humoral responses effectively without major interference on the cell mediated immunity.

Herbal supplement formula of Elephantopus scaber and Sauropus androgynus promotes IL-2 cytokine production of CD4+T cells in pregnant mice with typhoid fever

AbstractProduction of IL-2 by CD4+ T cells is shown to be suppressed in pregnant women infected by bacteria such as Salmonella typhi. Elephantopus scaber and Sauropus androgynus may be used as herbal supplement to ameliorate this condition. This study aimed to investigate the efficacy of E. scaber and S. androgynus formulation to promote lymphoid proliferation and CD4 cytokine productions. The pregnant mice were randomly divided into seven experimental groups: K- (control), K+ (with S. typhi), P1 (S. typhi + E. scaber 100%), P2 (S. typhi E. scaber 75% and S. androgynus 25%), P3 (S. typhi+ E. scaber 50% and S. androgynus 50%), P4 (S. typhi+scaber 25% and S. androgynus 75%), and P5 (S. typhi S. androgynus 100%). FACS analysis was done on day 18. Typhoid fever caused decreasing IL-2 and IFN-γ and in contrast increasing IL-4 production. In this experiment we clearly showed that typhoid fever decreased the amount of CD4 T cells but rather increased the amount of B cells. Formulation of E. scaber and S. andogynus was able to ameliorate the condition by increasing IL-2, IFN-γ, CD4 T cells and decreasing both IL-4 cytokine production and the amount of B cells.

The Effect of Granulocyte-Colony-Stimulating Factor (G-CSF) on T Cell Polarization in Vitro: A Direct Comparison Between Nivestim® and Neupogen®

Introduction Recombinant granulocyte colony stimulating factor (G-CSF) such as filgrastin (NeupogenÒ) is widely used to mobilize peripheral blood stem cells (PBSC) in healthy donors prior to allogeneic stem cell transplantation (all-SCT). In comparison to the bone marrow harvest, the G-CSF mobilized graft has a higher content of donor-derived T cells, the primary mediators of acute graft versus host disease (aGvHD). However, the incidence of aGvHD is identical suggesting a modulatory effect of Neupogen on T cells. The differentiation of allo-T cells to a T-helper 1 (Th1) phenotype polarizes the cells to produce IFN-g and IL-2, and this in turn promotes the development of GvHD. Conversely, recent evidence suggests that T-helper 2 (Th2) cells that produce IL-4 and IL-10 protects against GvHD. In healthy donors, G-CSF (NeupogenÒ) has been shown to decrease IFN-g and increase IL-4 production. A finding that is also observed under specific stimulatory condition in vitro.The recent patent expiry on G-CSF (Neupogen®) has prompted the development of alternative forms of G-CSF – called biosimilars. These molecules are structurally equivalent but their biological mode of action is currently under review. However, biosimilar G-CSF has not been accepted for routine stem cell mobilization in healthy donors primarily due to a lack of data about their safety in this cohort. In addition, no data exists of their influence on T cell modulation, which will potentially have a significant effect on aGvHD in the recipient. The primary objective of this study was to investigate the in vitro effects of Nivestim®, a biosimilar G-CSF that has been approved by the Therapeutic Goods Administration in Australia, and compared to the reference product filgrastim (Neupogen®) on human CD4+ T cells obtained from healthy volunteers.Results PBMC from 10 healthy volunteers, were cultured in the presence of Nivestim® or Neupogen® (both at 100 ng/ml), and stimulated 24 hrs later with either (1) anti-CD3 MoAb; (2) Phytohaemagglutin (PHA) or (3) PMA plus Ionomycin. The effects of Nivestim® and Neupogen® were examined on Th1 and Th2 cytokine profiles (IFN-g and IL-4 respectively), Th-specific transcriptional regulators, and T cell proliferation and survival.Our findings showed that CD4+ T cells from PBMC cultures produced significant levels of IFN-g following T cell activation. However, in the presence of Nivestim® or Neupogen®, the production of IFN-g was notably reduced and IL-4 levels were increased. These findings were consistent regardless of whether the T cell receptor was stimulated directly, or by-passed through the activation of proximal signaling molecules.Conclusion Whilst this pattern of Th2 polarization was not observed for all healthy volunteers, the biological effects of Nivestim® was comparable to Neupogen® in all cases. These findings have established that Nivestim® has an immunomodulatory effect on Th1/Th2 polarization in vitro that is equivalent to the reference product Neupogen®. Our findings will assist in facilitating Nivestim’s use for stem cell mobilization in healthy donors. DisclosuresMifsud:Hospira: Research Funding. Ismail:Hospira: Research Funding. de Valle:Hospira: Research Funding. Spencer:Hospira: Research Funding. Patil:Hospira: Research Funding. Grigoriadis:Hospira: Research Funding. Gugasyan:Hospira: Research Funding.

Synergistic and Additive Effects of Cimetidine and Levamisole on Cellular Immune Responses to Hepatitis B virus DNA Vaccine in Mice

We and others have previously shown that both cimetidine (CIM) and levamisole (LMS) enhance humoral and cellular responses to DNA vaccines via different mechanisms. In this study, we investigated the synergistic and additive effects of CIM and LMS on the potency of antigen-specific immunities generated by a DNA vaccine encoding the hepatitis B surface antigen (HBsAg, pVax-S2). Compared with CIM or LMS alone, the combination of CIM and LMS elicited a robust HBsAg-specific cellular response that was characterized by higher IgG2a, but did not further increase HBsAg-specific antibody IgG and IgG1 production. Consistent with these results, the combination of CIM and LMS produced the highest level of IL-2 and IFN-γ in antigen-specific CD4(+) T cells, whereas the combination of CIM and LMS did not further increase IL-4 production. Significantly, a robust HBsAg-specific cytotoxic response was also observed in the animals immunized with pVax-S2 in the presence of the combination of CIM and LMS. Further mechanistic studies demonstrated that the combination of CIM and LMS promoted dendritic cell (DC) activation and blocked anti-inflammatory cytokine IL-10 and TGF-β production in CD4(+) CD25(+) T cells. These findings suggest that CIM and LMS have the synergistic and additive ability to enhance cellular response to hepatitis B virus DNA vaccine, which may be mediated by DC activation and inhibition of anti-inflammatory cytokine expression. Thus, the combination of cimetidine and levamisole may be useful as an effective adjuvant in DNA vaccinations for chronic hepatitis B virus infection.

Azithromycin and spiramycin induce anti-inflammatory response in human trophoblastic (BeWo) cells infected by Toxoplasma gondii but are able to control infection

Toxoplasma gondii is an important pathogen which may cause fetal infection if primary infection. Our previous studies have used human choriocarcinoma trophoblastic cells (BeWo cell line) as experimental model of T. gondii infection involving placental microenvironment. This study aimed to examine the effects of azithromycin and spiramycin against T. gondii infection in BeWo cells. Cells were treated with different concentrations of the macrolide antibiotics and analyzed first for cell viability using thiazolyl blue tetrazole (MTT) assay. As cell viability was significantly decreased with drug concentrations higher than 400 μg/mL, the concentration range used in further experiments was from 50 to 400 μg/mL. The number of infected cells and intracellular replication of T. gondii decreased after treatment with each drug. The infection induced up-regulation of the macrophage migration inhibitory factor (MIF), which was also enhanced in infected cells after treatment with azithromycin, but not with spiramycin. Analysis of the cytokine profile showed increase TNF-α, IL-10 and IL-4 production, but decreased IFN-γ levels, were detected in infected cells and treated with each drug. In conclusion, treatment of human trophoblastic BeWo cells with with azithromycin or spiramycin is able to control the infection and replication of T. gondii. In addition, treatment with these macrolides, especially with azityromycin induces an anti-inflammatory response and high MIF production, which can be important for the establishment and maintenance of a viable pregnancy during T. gondii infection.

Propolis effect on Th1/Th2 cytokines production by acutely stressed mice

Aim of the study Propolis has gained special attention due to its biological properties, however, little is known about its immunomodulatory effects in stress conditions. The purpose of this study was to investigate propolis effect on Th1/Th2 cytokines production by spleen cells of acutely stressed mice. Serum corticosterone concentration was determined as a stress indicator. Materials and methods Male BALB/c mice were submitted to restraint stress and treated with propolis (200 mg/kg) for 3 days. Supernatants of splenocytes cultures were assessed for Th1/Th2 cytokines determination. Results Regarding Th1 cytokines production, no alterations were seen in IL-2 production; however, IFN-γ production was inhibited in stressed mice, even when treated with propolis. As to Th2 cytokines, IL-4 was inhibited in stressed mice, but normal levels were seen when these animals were treated with propolis. No significant differences were found in IL-10 production between the experimental groups. Stressed groups (treated or not with propolis) showed higher corticosterone concentrations in comparison to control group. Conclusions Data suggest that propolis treatment was not able to counteract the stress-induced immunosuppressive effect on IFN-γ production; however, propolis showed an immunorestorative role, increasing IL-4 production in stressed mice, favoring humoral immune response during stress. Since the exact mechanisms of this natural product on immune system are still unclear, further studies are still required for a better comprehension of propolis use as a therapeutic alternative against the stress-induced negative effects that could lead to the development of various diseases.

Mesenchymal stem cells overexpressing interleukin-10 attenuate collagen-induced arthritis in mice

Mesenchymal stem cells (MSCs) have the inherent ability to migrate to multiple organs and to exert immunosuppressive activity. The aim of this study was to investigate the anti-arthritogenic effects of interleukin (IL)-10-transduced MSCs (IL-10-MSC) on the development of inflammatory arthritis. DBA/1 mice were immunized with type II collagen (CII) to induce inflammatory arthritis and then injected weekly three times with IL-10-MSCs 21 days after primary immunization. Control mice received vehicle or MSCs alone. Serum anti-CII antibody and T cell response to CII were determined. The results showed that cultured IL-10-MSCs were able to secrete high amounts of IL-10 in vitro. Injection of IL-10-MSCs decreased the severity of arthritis significantly. However, there was no difference in arthritis severity between mice treated with MSC and vehicle alone. Anti-CII antibody titres in the sera and T cell proliferative response to CII in lymph node cells were decreased significantly in mice treated with IL-10-MSCs compared with vehicle-treated mice. Serum IL-6 level was also decreased by the administration of IL-10-MSCs. In contrast, spleen cells of IL-10-MSC-treated mice produced higher amounts of IL-4 than those of control mice. Interestingly, although not as potent as IL-10-MSCs, injection of naive MSCs alone decreased serum levels of IL-6 and anti-CII antibody, while increasing IL-4 production from cultured splenic cells. Taken together, systemic administration of genetically modified MSCs overexpressing IL-10 inhibits experimental arthritis not only by suppressing autoimmune response to CII but also by regulating cytokine production, and thus would be a new strategy for treating rheumatoid arthritis.

Cytokine production in varicella zoster virus-stimulated limiting dilution lymphocyte cultures.

Human blood lymphocytes were stimulated with varicella zoster virus (VZV) antigen in limiting dilution cultures and the amounts of interferon-gamma (IFN-gamma) and IL-4 measured in the supernatants. The results indicate that up to 85% of proliferating cells of young adults produce IFN-gamma and up to 10% make IL-4. At limiting dilution, few if any wells were positive for both IFN-gamma and IL-4. The amount of IFN-gamma per well increased in the presence of antibody to IL-4, but anti-IFN-gamma not increase IL-4 production. The frequency of wells containing IFN-gamma was lower in subjects < 19 or > 55 years of age, and the amounts of IFN-gamma in positive wells was significantly lower in cultures of the older subjects' lymphocytes. The frequency of IL-4-making cells did not fall significantly with age. The data suggest that the age-related decline in the frequency of blood T cells which responds to VZV affects mainly the cells with a Th1-like cytokine phenotype.

A small amount of tetrachloroethylene ingestion from drinking water accelerates antigen-stimulated allergic responses

Previously, we observed that tetrachloroethylene (perchloroethylene, PCE) increased histamine release and inflammatory mediator production from antigen-stimulated mast cells. In this study, we examined the enhancing effect of low concentrations of PCE in drinking water on antigen-stimulated allergic responses. After exposure of Wistar rats to PCE in drinking water for 2 or 4 weeks, we performed a passive cutaneous anaphylaxis (PCA) reaction. PCE exposure for 4 weeks enhanced PCA reaction in a dose-dependent manner. In pathological studies, PCE exposure for 2 weeks exacerbated inflammation characterized by infiltration of lymphocytes and accumulation of mast cells around the vessel. Non-purified mast cells (NPMCs) from rats treated with 1 mg/L PCE in drinking water for 2 weeks increased antigen-stimulated histamine release. Furthermore, the leukocytes of rats treated with PCE in drinking water for 4 weeks showed increased interleukin (IL)-4 expression. The mechanism of enhancing the PCA reaction is assumed to be that PCE increases IL-4 production and PCE causes T helper (Th) 1/Th2-type helper T-cell imbalance and increases histamine release from excessively accumulated mast cells. The results suggest that the intake of PCE in drinking water, even at a low concentration, leads to the initiation and acceleration of allergic diseases.

Selective Effect of Mercury on Th2-Type Cytokine Production in Humans

Mercury induces autoimmune disease and increases IL-4 production and IgE levels in certain rodent strains. The object of this study was to determine if mercury was capable of inducing Th2 cytokine production in human leucocytes. Human peripheral blood mononuclear cells (PBMC) were incubated with PMA/ionomycin or Con A in the presence or absence of methyl mercury (CH3Hg) or mercuric chloride (HgCl2). IL-4 and gamma-IFN were measured by ELISA. RESULTS: IL-4 production significantly increased at low concentrations of CH3Hg (0.5 uM, p < 0.01), while gamma-IFN production was suppressed starting at CH3Hg 2 uM (p = 0.004). Inorganic mercury (HgCl2) increased IL-4 only at concentrations 10–20 times higher than CH3Hg. These findings suggest a mechanism by which mercury could trigger or potentiate TH2 cytokine production in humans.

Immunomodulating Effects of Fractioned Polysaccharides Isolated from Yu-Ping-Feng-Powder in Cyclophosphamide-Treated Mice

Yu-Ping-Feng-Powder (YP), a traditional Chinese medicine prescription, is widely applied in China for the cure and prevention of diseases related to immunodeficiency. To test whether the fractioned polysaccharides (YPF-P) isolated from YP have immunomodulating activities, the effects of YPF-P on cyclophosphamide (Cy)-treated mice were studied in relation to phagocytosis of macrophage, splenocyte proliferation, and humoral, and cellular immunity parameters. It was found that YPF-P enhances phagocytic activity, augments ConA- or LPS-stimulated T cell proliferation, increases the quantitative haemolysis of SRBC (QHS) and delayed-type hypersensitivity reaction (DTH) to dinitrofluorobenzene. Hence, YPF-P restored the immuno-competence suppressed by Cy. YPF-P also augmented IL-2 and IFN-gamma production, but failed to increase IL-4 production, which indicates that there is high probability that it enhance Th1 function. These results suggested that YPF-P has immunomodulating effects and that the polysaccharides constitute one of the active components of YP.

IL-15 induces mast cell migration via a pertussis toxin-sensitive receptor

IL-15 induces proliferation, inhibits apoptosis and increases IL-4 production in murine mast cells. There is evidence that these activities are mediated via the uncharacterised receptor, IL-15R-X, rather than the classical three-chain IL-15 receptor. Effects of IL-15 on important aspects of mast cell biology, such as migration and degranulation, are unknown. We report that IL-15 induces migration of murine and human mast cells in a dose-dependent and biphasic manner, with peaks of migration occurring at approximately 10(-15) and approximately 10(-9) M. The potency of the response was similar to that induced by other well-established mast cell chemoattractants. Competition assays performed with murine and human mast cells indicate that both peaks of migration are due to chemotaxis. Pre-treatment of cells with pertussis toxin (PTX), a guanine nucleotide-binding regulatory protein (G-protein) inhibitor, resulted in complete inhibition of murine mast cell migration at approximately 10(-15) M IL-15, and human mast cell migration at approximately 10(-15) and approximately 10(-9) M. This demonstrates that murine and human mast cells express a PTX-sensitive receptor, activated in response to IL-15. Additionally, IL-15 did not induce degranulation in murine mast cells. Locally-produced IL-15 may contribute to mast cell recruitment during inflammatory responses, thereby acting as a linking cytokine between innate and adaptive arms of the immune system.

Akt decreases lymphocyte apoptosis and improves survival in sepsis.

Sepsis induces extensive death of lymphocytes that may contribute to the immunosuppression and mortality of the disorder. The serine/threonine kinase Akt is a key regulator of cell proliferation and death. The purpose of this study was to determine whether overexpression of Akt would prevent lymphocyte apoptosis and improve survival in sepsis. In addition, given the important role of Akt in cell signaling, T cell Th1 and Th2 cytokine production was determined. Mice that overexpress a constitutively active Akt in lymphocytes were made septic, and survival was recorded. Lymphocyte apoptosis and cytokine production were determined at 24 h after surgery. Mice with overexpression of Akt had a marked improvement in survival compared with wild-type littermates, i.e., 94 and 47% survival, respectively, p < 0.01. In wild-type littermates, sepsis caused a marked decrease in IFN-gamma production, while increasing IL-4 production >2-fold. In contrast, T cells from Akt transgenic mice had an elevated production of IFN-gamma at baseline that was maintained during sepsis, while IL-4 had little change. Akt overexpression also decreased sepsis-induced lymphocyte apoptosis via a non-Bcl-2 mechanism. In conclusion, Akt overexpression in lymphocytes prevents sepsis-induced apoptosis, causes a Th1 cytokine propensity, and improves survival. Findings from this study strengthen the concept that a major defect in sepsis is impairment of the adaptive immune system, and suggest that strategies to prevent lymphocyte apoptosis represent a potential important new therapy.

Intracellular thiols contribute to Th2 function via a positive role in IL-4 production.

A number of lung diseases, including many interstitial lung diseases and HIV infection, are associated with decreases in intracellular thiols. Altered Th1/Th2 T cell balance has also been associated with disease progression in many of the same diseases. IFN-gamma and IL-4 are critical effector cytokines of Th1 and Th2 cells, respectively. To determine the effect of thiols on the production of IFN-gamma and IL-4 by splenocytes, cells were incubated in the presence and the absence of N-acetylcysteine (NAC) and stimulated with alphaCD3 or alphaCD3 and IL-12. Augmenting intracellular soluble thiol pools ( approximately 2-fold) with 15 mM NAC blocked induction of IFN-gamma and increased production of IL-4 without causing significant changes in intracellular glutathione levels. The effect of NAC on IL-4 production was not linked to an increase in STAT6 phosphorylation, as STAT6 levels were decreased, nor did the increase in IL-4 occur with purified CD4 cells. We found that NAC increased splenocyte IL-4 production via an effect on APCs. We also found that NAC increased two IL-4 relevant transcription factors (AP-1) and NFATc. These studies suggest that increasing intracellular reduced thiol pools decreases IL-12 signaling and IFN-gamma production, while increasing IL-4 production. The sum of these effects may contribute to alterations in the balance between Th1 and Th2 responses in lung diseases associated alterations in intracellular thiol pools.

Albuterol increases IL-4 production by ragweed-stimulated peripheral blood mononuclear cells

Albuterol increases IL-4 production by ragweed-stimulated peripheral blood mononuclear cells

IL-4 promotor gene polymorphism in heart transplantation

IL-4 is a cytokine of the Th2 subtype, secreted mainly by activated T- lymphocytes. IL-4 acts by down regulation of Th1 responses of macrophage and Th1 cells. On the other hand, IL-4 stimulates growth and differentiation of Th2 lymphocytes and mast cells. In transplantation Th2 cells are believed to be involved in induction of graft tolerance. Previous studies revealed that patients with a high frequency of IL-4 producing precursor T- helper cells (pHTL) before heart transplantation (HTX) had no or less rejection episodes compared to patients with low frequency of IL-4 producing pHTL (van Hoffen et al., Transpl Int. 13,S216,2000). Recently, single nucleotide polymorphisms (SNP) in the promoter regions of various cytokine genes have been identified. These SNP influence promoter strength and hence production of the cytokine. The promoter region of the IL-4 gene contains three SNP at positions -590 (C>T), -285 (C>T) and -81 (A>G) from the transcriptional start site. Three polymorphic alleles (resp T, T and G) increase promoter strength. We hypothesize that presence of these polymorphic alleles decreases rejection by increasing IL-4 production. Seventy HTX patients and 61 donors were genotyped for all three SNP by sequencing. SNP at -285 and -81 were not polymorphic in this study. We found 66 % CC, 30% CT and 4% TT at position -590 in patients and 80% CC, 18% CT, 2%TT in donors. Our results show that the incidence of rejection is significantly lower in patients receiving the T-allele from their donor compared to patients who did not ( x2 = 4.52, p= 0.034, relative risk = 3.31), regardless of the patients own haplotype. This indicates that IL-4 production within the donor heart and by cells from that donor is important. Potential candidates for this IL-4 production are various stromal elements, but also interstitial mast cells may be responsible.

Interleukin-11 modulates Th1/Th2 cytokine production from activated CD4+ T cells.

Recombinant human interleukin-11 (rHuIL-11) is a pleiotropic cytokine with effects on multiple cell types. rHuIL-11 reduces activated macrophage activity and downregulates production of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). In vitro and in vivo, rHuIL-11 inhibits production of key immunostimulatory cytokines, including IL-12 and interferon-gamma (IFN-gamma). rHuIL-11 has recently demonstrated immunomodulatory activity to downregulate IFN-gamma production, increase IL-4 production, and reduce inflammatory tissue injury in a human psoriasis clinical trial. The cellular mechanisms of these effects are not fully elucidated. We demonstrate here that expression of gp130 and IL-11 receptor (IL-11R) alpha mRNA, components of the IL-11R complex, are detected in human and murine CD4(+) and CD8(+) lymphocytes, suggesting that rHuIL-11 can directly interact with T cells. In a cell culture model of murine T cell differentiation, rHuIL-11 acts to inhibit IL-2 production as well as IL-12-induced IFN-gamma production and enhances IL-4 and IL-10 production. rHuIL-11 had no effect on T cell proliferation. The ability of rHuIL-11 to modulate cytokine production from activated CD4(+) T cells provides a mechanism through which rHuIL-11 may ameliorate such inflammatory diseases as psoriasis.

Absence of functional inducible NO synthase enhances the efficacy of tolerance induced by high dose antigen feeding.

Recent studies have suggested that IL-12 and IFN-gamma may impair the ability of fed Ag to induce systemic tolerance. Because both of these cytokines can function to directly or indirectly induce inducible NO synthase (iNOS) expression, we have investigated whether the functional expression of iNOS regulates oral tolerance. C57BL/6J wild-type or C57BL/6J NOS2(-/-) mice were gavaged with a single dose of 20 mg of keyhole limpet hemocyanin (KLH), followed by s.c. immunization with KLH/CFA. In the absence of feeding Ag, several parameters of the immune response were more robust in C57BL/6J NOS2(-/-) mice following KLH/CFA immunization, including the magnitude of the delayed-type hypersensitivity response, the proliferative response, and the production of IFN-gamma and IL-2 by Ag-activated draining lymph node cells. These heightened responses in the C57BL/6J NOS2(-/-) mice are still effectively inhibited by feeding KLH. Feeding KLH to the C57BL/6J NOS2(-/-) mice elicited heightened TGF-ss1 production by Ag-activated lymphocytes, as well as augmented total IgG, IgG1, and IgG2a responses to KLH/CFA compared with that seen in Ag-fed wild-type mice. Feeding Ag to the NOS2(-/-) mice suppressed proliferative responses and IFN-gamma production, while increasing IL-4 production and the IgG1/IgG2a ratio even following a booster immunization of KLH/CFA. Administrating L-N:(6)-(1-iminoethyl)-lysine. 2HCl to wild-type mice during the period of Ag feeding reproduced the high TGF-ss1 production seen in Ag-activated lymphocytes from Ag-fed NOS2(-/-) mice. Feeding KLH is followed by transient up-regulation of NOS2 mRNA expression in the Peyer's patches of wild-type mice. Selective inhibition of NOS2 may be a simple way to augment tolerogenic mucosal immune responses.