Interleukin-4 induces a switch of human intestinal mast cells from proinflammatory cells to Th2-type cells

BACKGROUND: During the last years, mast cells have been recognized as a potent cellular source of multiple cytokines. However, little is known about the regulation of cytokine production by mature human mast cells derived from mucosal sites. METHODS: Human mast cells were isolated from intestinal mucosa and cultured for 14 days in the presence of stem cell factor (SCF) alone or in combination with IL-4. Mast cells were then stimulated by IgE receptor cross-linking or bacterial infection and cytokine production was examined by RT-PCR and ELISA. RESULTS: We found that human intestinal mast cells produce proinflammatory cytokines such as TNF-alpha, IL-1beta and IL-6 without further stimulation. Stimulation of the cells with gram-negative bacteria (Escherichia coli and others) caused an upregulation of TNF-alpha expression. Following IgE receptor cross-linking, we found additional expression of the Th2 cytokines IL-3, IL-5 and IL-13. Interestingly, mRNA for IL-3, IL-5 and IL-13 was also expressed in unstimulated mast cells provided they were cultured in the presence of SCF and IL-4. Moreover, IL-4 rendered mast cells capable of releasing IL-5 in response to bacterial challenge. CONCLUSION: In the presence of the mast cell survival factor SCF, mature human mast cells produce predominantly proinflammatory cytokines, whereas in the presence of SCF and IL-4, mast cells produce not only proinflammatory but also Th2 cytokines.     

IL-17 and IL-17F modulate GM-CSF production by lung microvascular endothelial cells stimulated with IL-1beta and/or TNF-alpha

In this study, we investigated the roles of CD4 T cell cytokines IL-17 and IL-17F in GM-CSF production from lung microvascular endothelial cells (LMVECs). While a wide range of doses of IL-17 or IL-17F alone did not induce GM-CSF release from LMVECs, IL-17 had an enhancing effect on macrophage-derived IL-1beta- and TNF-alpha-induced GM-CSF mRNA expression and production, whereas IL-17F had an enhancing effect on IL-1beta-induced GM-CSF production, but a marked inhibitory effect on TNF-alpha-induced secretion. GM-CSF production was further enhanced with the combination of three cytokines IL-1beta, TNF-alpha and IL-17 or IL-17F. Additionally, when Th1 or Th2 cytokine was combined with IL-1beta or TNF-alpha, both Th1 and Th2 cytokines had a modest stimulatory effect on TNF-alpha-induced GM-CSF production, whereas IL-4 and IFN-gamma profoundly attenuated IL-1beta-induced secretion. Moreover, the regulation by IL-17 plus Th1 or Th2 cytokine of GM-CSF production from LMVECs treated with IL-1beta or TNF-alpha was dependent on the concentration of IL-17. Our findings indicate that IL-17 and IL-17F play a differential regulatory role in GM-CSF production by LMVECs stimulated with IL-1beta and/or TNF-alpha, which is sensitive to Th1 and Th2 cytokine modulation.     

Regulatory roles of IL-17 and IL-17F in G-CSF production by lung microvascular endothelial cells stimulated with IL-1beta and/or TNF-alpha

The role of the interleukin (IL)-17 family members in the regulation of G-CSF production by lung microvasculature has not been elucidated yet. We therefore investigated the effects of IL-17 and IL-17F on the regulation of G-CSF production by lung microvascular endothelial cells (LMVECs). While a wide range of doses of IL-17 or IL-17F alone did not up-regulate G-CSF production from primary human LMVECs, IL-17 had an enhancing effect on macrophage-derived IL-1beta- and TNF-alpha-induced G-CSF production, whereas IL-17F had an enhancing effect on IL-1beta-induced production, but an inhibitory effect on TNF-alpha-induced secretion. G-CSF production was further enhanced with the combination of three cytokines IL-1beta, TNF-alpha and IL-17. In contrast, three cytokines IL-1beta, TNF-alpha and IL-17F were combined together, G-CSF production was less than that induced by IL-1beta or IL-1beta plus TNF-alpha or IL-17F. Moreover, IL-17 plus Th1 or Th2 cytokine had a modest stimulatory effect on TNF-alpha-induced G-CSF production, whereas IL-17 plus IFN-gamma had an inhibitory effect on IL-1beta-induced release. Similarly, IL-17F plus IL-10, IL-13 or IFN-gamma had an inhibitory effect on IL-1beta-induced production. Our findings indicate that CD4 T cell cytokines IL-17 and IL-17F play a differential regulatory role in G-CSF production by LMVECs stimulated with IL-1beta and/or TNF-alpha, which is also sensitive to Th1 and Th2 cytokine modulation.     

Modulation of IL-2, IFN-gamma, TNF-alpha and IL-4 production in mice of different ages by thymopentin.

The effect of an immunomodulator drug thymopentin (TP5) on the production of various cytokines (IFN-gamma, IL-2, IL-4, TNF-alpha) in mice of different ages has been studied. TP5 enhanced IL-2, TNF-alpha and IFN-gamma production but reduced the IL-4 secretion by splenocytes from aged mice (greater than 120 week old) in vitro. However, it had no effect on the IL-2, IFN-gamma, TNF-alpha or IL-4 production by splenocytes from young and adult mice. TP5 injected subcutaneously was able to induce high levels of IL-2 production by splenocytes from all groups of mice. The TP5 effect on TNF-alpha and IFN-gamma was similar, even though it was significant only in old mice. Furthermore, TP5 was able to significantly reduce IL-4 production in old mice, which normally produced high levels of this cytokine after mitogen stimulation. Since it has been observed in the mouse that the Th1 cells secrete IFN-gamma and IL-2, whereas the Th2 cells preferentially produce IL-3, IL-4 and IL-5, these results indicate that the immunopotentiatory activity of TP5 is due to the preferential up-regulation of Th1 cells.     

A synergistic relationship between TNF-alpha, IL-1 beta, and TGF-beta 1 on IL-6 secretion by the IEC-6 intestinal epithelial cell line.

Intestinal epithelial cells are known to secrete a variety of cytokines and may play a role in the immune response at the intestinal mucosa. However, the regulatory mechanisms that govern the secretion of these cytokines are largely unknown. In this report, we have focused on the cytokine interactions that regulate interleukin (IL)-6 secretion by the non-transformed rat small intestinal epithelial cell line IEC-6. Tumour necrosis factor-alpha (TNF-alpha) was found to enhance both IL-6 mRNA expression and protein secretion by the IEC-6 cells. Furthermore, TNF-alpha acted in synergy with either transforming growth factor-beta 1 (TGF-beta 1) or IL-1 beta to greatly enhance IEC-6 cell IL-6 secretion. Although the IEC-6 cells are known to produce TGF-beta, autocrine-secreted TGF-beta was found to have no effect on the elevated IL-6 secretion induced by both TNF-alpha plus IL-1 beta. However, the addition of activated TGF-beta 1 to IEC-6 cultures stimulated with both TNF-alpha and IL-1 beta resulted in greatly elevated levels of IL-6 secretion. Therefore, activated TGF-beta 1 can augment IL-6 secretion stimulated by TNF-alpha and IL-1 beta, either alone or in combination, suggesting that intestinal epithelial cell IL-6 secretion may be under the control of a cytokine network at the intestinal mucosa.     

Enhanced secretion of tumour necrosis factor-alpha, IL-6, and IL-1 beta by isolated lamina propria mononuclear cells from patients with ulcerative colitis and Crohn's disease.

The perpetuation of inflammation in ulcerative colitis and Crohn's disease may be regulated in part by an increased secretion of proinflammatory cytokines due to either an appropriate response to initial stimulating agents, and/or due to an impaired down-regulation of cytokine secretion. The aim of this study was to determine the secretion patterns of the proinflammatory cytokines tumour necrosis factor-alpha (TNF-alpha), IL-6 and IL-1 beta, from isolated lamina propria mononuclear cells (LPMNC) isolated from colonic biopsies from patients with untreated ulcerative colitis or Crohn's disease. LPMNC isolated from involved inflammatory bowel disease (IBD) mucosa spontaneously produced increased amounts of TNF-alpha, and IL-6, and IL-1 beta. The TNF-alpha secretion from IBD LPMNC could be further enhanced by pokeweed mitogen stimulation. The secretion patterns of TNF-alpha and IL-1 beta by LPMNC from patients with either ulcerative colitis or Crohn's disease demonstrated a close correlation with the degree of tissue involvement and mucosal inflammation. LPMNC from non-involved ulcerative colitis mucosa secreted markedly increased levels of IL-6 compared with non-involved Crohn's disease mucosa or control mucosa. The heightened IL-6 secretion from LPMNC from non-involved ulcerative colitis mucosa without visible or microscopic signs of inflammation indicates that the pathophysiologic mechanisms involved in the initiation of inflammation may differ between ulcerative colitis and Crohn's disease. The determination of proinflammatory cytokine secretion by isolated LPMNC from colonoscopic biopsies may be a sensitive method for monitoring the severity of mucosal inflammation in IBD patients.     

Effects of tumour necrosis factor-alpha (TNF-alpha), IL-1 beta and monocytes on lymphokine-activated killer (LAK) induction from natural killer (NK) cells and T lymphocytes.

Roles of monocytes and cytokines were investigated on LAK induction from T and NK cells. Monocytes augmented more T-LAK induction than did NK-LAK. Expression of IL-1 beta, TNF-alpha and interferon-gamma (IFN-gamma)-mRNA and their cytokine production were superior in NK cells compared with T cells in parallel with their LAK activities. An increase of TNF-alpha, IL-1 beta and IFN-gamma production was induced by co-culturing NK or T cells with autologous monocytes. The augmentation of T cell cytokine production and T-LAK activity by monocytes was more prominent than that of NK cells. TNF-alpha and IL-1 beta were generated 24 h after IL-2 stimulation, and these cytokines were able to almost substitute for monocytes in LAK induction. Conversely, LAK induction was almost completely suppressed by both anti-IL-1 beta and anti-TNF-alpha antibodies, if they were added within 24 h after the start of the LAK induction. IFN-gamma, which was produced at a later stage, scarcely affected LAK induction in spite of the cooperation with TNF-alpha. The results obtained indicate conclusively that the superiority of NK-LAK depends on their superior productivity of both IL-1 beta and TNF-alpha, and that the up-regulation of LAK induction by monocytes is largely due to the enhanced generation of both cytokines.     

IL-18 together with anti-CD3 antibody induces human Th1 cells to produce Th1- and Th2-cytokines and IL-8

Although IL-18 was initially regarded as a factor that enhances IFN-gamma production from Th1 cells, later studies revealed its potential to induce Th2 cytokine production from T cells, NK cells and basophils/mast cells. Very recently, we demonstrated that passively transferred memory phenotype Th1 cells induce airway inflammation and hyperresponsiveness in a host mouse by production of Th1-, Th2-cytokines, GM-CSF and chemokines, when the transferred cells are stimulated in the host mice with nasally administered Ag and IL-18. Moreover, IL-18 is suggested to contribute to asthma exacerbation in human patients. Therefore, it is important to determine whether human Th1 cells also have the potential to produce these soluble factors when stimulated with anti-CD3 and IL-18 in vitro. Here we demonstrated that only Th1 cells, but not Th2 cells, produce IFN-gamma, IL-13, GM-CSF and IL-8 after stimulation with anti-CD3 and IL-18. Furthermore, highly purified IFN-gamma-producing Th1 cells have the same potential. Thus, human Th1 cells may become very harmful cells, when stimulated with Ag and IL-18 in vivo, and produce IFN-gamma, IL-13, GM-CSF and IL-8, which in combination might induce severe inflammation such as airway inflammation.     

MD41, a novel T helper 0 clone,mediates mast-cell dependent delayed-type hypersensitivity in mice

In a previous study on mouse, we have shown that delayed-type hypersensitivity (DTH) could be classified into two types according to MC requirement. The first type of DTH could be elicited by sensitization with methylated human serum albumin (MHSA) in complete Freund's adjuvant (CFA) in both wild type and mast-cell deficient (W/Wv) mice. The second type could be elicited by MHSA in incomplete Freund's adjuvant (IFA) sensitization in wild type but not W/Wv mice. While the former was related to classic tuberculin (tbc)-type DTH, the latter appeared to be a novel mast-cell dependent DTH (MD-DTH). In order to investigate the mechanism of MD-DTH, in this study, we generated an effector T-cell clone (MD41) from lymph node cells of MHSA in IFA-sensitized mice and analysed its pattern of cytokine production. Our results from cytokine assays show that following antigen stimulation, MD41 cells produce significant amounts of the T helper 1 (Th1) cytokine interferon-gamma (IFN-gamma) as well as the Th2 cytokines interleukin (IL)-4 and IL-10. In addition, double staining for IL-4 and IFN-gamma revealed that MD41 cells produce both Th1- and Th2-type cytokines simultaneously, which suggest that MD41 represents a Th0 clone rather than a mixture of Th1 and Th2 clones. Adoptive transfer of MD41 cells into wild-type mice resulted in the development of DTH skin reactions similar to those produced by active sensitization, with very similar histological findings. However, DTH skin reactions could not be induced in W/Wv mice unless first reconstituted with normal bone marrow MC (BM-MC). Therefore, our study suggests that in conjunction with tissue MC, MD41, a less-polarized MD-DTH-derived Th0 clone, is capable of developing murine DTH to the same extent as strongly polarized Th1 cells and mediates MD-DTH rather than tbc-type DTH.     

IL-10 deficiency prevents IL-5 overproduction and eosinophilic inflammation in a murine model of asthma-like reaction

Eosinophilic inflammation and bronchial mucus secretion are among the characteristic pathological changes in asthmatic reaction, which is mediated by Th2 type responses. Although it belongs to Th2 cytokines especially in the mouse, IL-10 is often considered an inhibitory cytokine for both Th1 and Th2 cells. In the present study, using a murine asthma model induced by ovalbumin (OVA), we demonstrated that endogenous IL-10 is critical for the development of asthma-like responses. Specifically, in comparison with wild-type controls, IL-10 gene knockout (KO) mice showed significantly reduced IL-5 production, eosinophilic inflammation and mucus production without notable changes in IL-4 and IgE responses following i. p. sensitization and subsequent intranasal challenge with OVA. In addition, Th1-related cytokine (IFN-gamma and IL-12) production in IL-10 KO mice was significantly higher than that in wild-type mice. The results suggest that endogenous IL-10 plays an important role in promoting pulmonary eosinophilic inflammatory reaction and mucus production during asthmatic reaction. The data also argue that IL-10 may be more influential in the development of IL-5-producing Th2 cells which differ from typical Th2 cells producing both IL-4 and IL-5.     

Increased IL-10 production during spontaneous apoptosis of monocytes

Monocytes/macrophages undergo apoptosis and are in contact with apoptotic cells both in vitro and in vivo. The data show that monocytes undergoing spontaneous apoptosis in vitro change their cytokine production profile. We demonstrate that the lipopolysaccharide (LPS)-induced production of interleukin-10 (IL-10) is up-regulated, while production of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) is either not affected or reduced. These differences seen both at the protein and mRNA level directly correlate with the appearance of apoptotic cells in the culture. Flow cytometry analysis using double staining, surface with annexin V and intracellular with anti-IL-10, suggested that annexin V-negative monocytes are the predominant source of IL-10. Analysis of sorted populations of monocytes indicated that the increase in IL-10 synthesis appears to result from direct interactions between non-apoptotic and apoptotic cells at the time of stimulation. Also non-apoptotic, freshly isolated monocytes produced more IL-10 upon stimulation with LPS, Staphylococcus aureus or zymosan when apoptotic neutrophils were added to the culture. In contrast, monocyte-derived macrophages did not produce more IL-10 in the presence of apoptotic neutrophils. Finally, we found that the presence of apoptotic monocytes in the culture may influence specific immune responses. The data show that in the presence of annexin V-positive monocytes CD4-positive memory T cells produce less IFN-gamma upon stimulation with purified protein derivative of tuberculin, which could be partially reversed by anti-IL-10 neutralizing antibodies. We conclude that these findings might illustrate the mechanisms operating within an inflammatory site and play an important immunoregulatory role during the resolution of inflammation and specific immune responses.     

IL-4, IL-10 and IL-13 down-regulate monocyte-chemoattracting protein-1 (MCP-1) production in activated intestinal epithelial cells

Several studies have demonstrated that intestinal epithelial cells play a major role in the initiation and perpetuation of intestinal inflammation by secreting proinflammatory cytokines and chemokines. MCP-1 is suggested to be a chemokine that plays a major part during intestinal inflammation in inflammatory bowel disease (IBD). Immunoregulatory cytokines such as IL-4, IL-10 and IL-13 have been described to exert anti-inflammatory properties on various cell types. The aim of our study was to determine the effect of Th2 cytokines on the production of MCP-1 by activated intestinal epithelial cells. We examined Caco-2 cells as well as intestinal epithelial cells which were isolated from surgical specimens. Production of the chemokine MCP-1 was determined under stimulated and non-stimulated conditions. IL-4, IL-10 and IL-13 were added to stimulated epithelial cells under various culture conditions. Supernatants were analysed for cytokine concentrations using ELISAs. Under stimulation with physiological agents like IL-1β or tumour necrosis factor-alpha (TNF-α), we observed markedly increased concentrations of MCP-1 in supernatants of Caco-2 cells and intestinal epithelial cells. IL-4, IL-10 and IL-13 all had the capacity to down-regulate the production of MCP-1 in Caco-2 cells as well as in freshly isolated epithelial cells. Caco-2 cells which were primed with Th2 cytokines 24 h before stimulation were subsequently decreased in their ability to be stimulated by IL-1β or TNF-α for MCP-1 production. As MCP-1 has been shown to play a major role during intestinal inflammation, the in vitro suppression of MCP-1 in enterocytes suggests the in vivo use of regulatory cytokines in patients with active IBD.     

IL-10 subfamily members: IL-19, IL-20, IL-22, IL-24 and IL-26

It has been reported that the CD4+ T cell is a very important source of interleukin 10 (IL-10), while CD8+ cells produce low amounts. IL-10 exerts several immune stimulating, as well as inhibitory effects. There are at least five novel human IL-10 family-related molecules: IL-19, IL-20, IL-22, IL-24, and IL-26. Activated T cells produce IL-19, IL-22 and IL-26, while IL-24 is produced by activated monocytes and T-cells. IL-20 induces cheratin proliferation and Stat-3 signal transduction pathway, while IL-22 induces acute-phase production by hepatocytes and neonatal lethality with skin abnormalities reminiscent of psoriasic lesions in humans. In addition, IL-22 mediates inflammation and binds class II cytokine receptor heterodimers IL-22 RA1/CRF2-4. This cytokine is also involved in immuno-regulatory responses. IL-26 (AK155) is a novel cytokine generated by memory cells and is involved in the transformed phenotype of human T cells after infection by herpes virus. All these new IL-10 subfamily member cytokines are strongly involved in immune regulation and inflammatory responses.     

Arthritis induced with cartilage-specific antibodiesis IL-4-dependent

It is widely believed that IL-4 exerts its influence by profiling the immune response during priming and expansion of immune cells, and thereby modulates the outcome of chronic inflammation. In the present investigation, collagen antibody-induced arthritis (CAIA) was used to delineate the role of IL-4 in a T cell-independent inflammatory phase. Mice predisposed to Th2 cytokines (BALB/c and STAT4-deficient mice) developed a more severe arthritis than mice biased towards Th1 cytokines (C57BL/6 and STAT6-deficient mice). Reduced incidence of CAIA was observed in IL-4-deficient mice compared to control littermates. Infiltrating cells in the paws of IL-4-sufficient mice had increased osteoclast activity and tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta secretion. Massive infiltration of granulocytes and joint and cartilage damage were present in arthritic paws. Depletion of IL-4 suppressed CAIA, which was abrogated by IFN-gamma neutralization. IL-1R- and IL-1RTNFR-deficient mice were completely resistant to CAIA. Thus, IL-4 promotes an antibody-mediated and TNF-alpha/IL-1beta-dependent inflammation in vivo.