Interferon γ modulates production of interleukin 1 and tumor necrosis factor by murine Kupffer cells

ABSTRACT— When mononuclear phagocytes, including Kupffer cells, are activated by various agents, they synthesize and release cytokines such as interleukin 1 (IL-1) and tumor necrosis factor (TNF). In this study, we examined the effect of in vitro Kupffer cell activation by recombinant murine interferon γ (IFNγ) on IL-1 and TNF secretion. IFNγ enhanced TNF production in the presence or absence of lipopolysaccharide (LPS), but suppressed IL-1 production by Kupffer cells. Because IFNγ also stimulated prostaglandin E₂ (PGE₂) production, the effect of indomethacin, which is an inhibitor of cyclooxygenase and which inhibits PGE₂ biosynthesis, on IL-1 and TNF production by Kupffer cells was examined. As a result, indomethacin enhanced TNF production by Kupffer cells, but had no effect on IL-1 synthesis. These results suggested that IFNγ modulates the production of IL-1 and TNF by Kupffer cells through different mechanisms.     

特发性肺纤维化患者辅助性T细胞1/辅助性T细胞2的研究

目的 对特发性肺纤维化(IPF)患者辅助性T细胞1(Th1)/辅助性T细胞2(Th2)进行研究,探讨Th1/Th2能否反映疾病的严重性,能否预测疾病的进展.方法 入选83例IPF患者,应用酶联免疫吸附测定法检测所有受试者血清、支气管肺泡灌洗液(BALF)中γ干扰素(IFNγ)、白细胞介素-4(IL-4)水平,并进行相关性分析.结果 (1)基线资料:IPF患者血清、BALF中IFNγ/IL-4比值(0.8±0.3;0.8±0.3)较对照组(1.4±0.2;1.4±0.2)显著降低;血清、BALF中IFNγ/IL-4比值与病程、呼吸困难评分、第1秒用力呼气容积(FEV1)占预计值百分比、用力肺活量(FVC)占预计值百分比、肺总量(TLC)占预计值百分比、最大去氧饱和度、6分钟步行距离(6MWD)、CT间质纤维化评分显著相关(血清:r值分别为-0.426、-0.623、0.487、0.455、0.517、-0.491、0.263、-0.569,P值均＜0.05;BALF:r值分别为-0.434、-0.637、0.480、0.456、0.501、-0.507、0.253、-0.605,P值均＜0.05);血清中IFNγ/IL-4比值与CT磨玻璃影评分呈正相关(r=0.340,P＜0.01).(2)随访:IPF患者血清中IFNγ、IL-4、IFNγ/IL-4在糖皮质激素治疗者与非糖皮质激素治疗者间差异无统计学意义.随访6个月后的呼吸困难评分、FEV1占预计值百分比、TLC占预计值百分比、CT磨玻璃影评分、CT间质纤维化评分、IFNγ和IL-4较基线值显著恶化.血清中IFNγ/IL-4比值变化与呼吸困难评分、FVC占预计值百分比、TLC占预计值百分比、肺一氧化碳弥散量占预计值百分比、6MWD、CT间质纤维化评分的变化显著相关(r值分别为-0.297、0.462、0.315、0.353、0.420、-0.307,P值均＜0.05).结论 IPF患者血清和BALF中Th1/Th2存在失衡,Th1/Th2可能反映IPF的严重性,随访时血清中Th1/Th2的变化可能会预测IPF的疾病进展.     

Crucial role of interleukin-10/interleukin-12 balance in the regulation of the type 2 T helper cytokine response in reactive arthritis

Objective. To investigate whether a predominant type 1 T helper (Thl) or Th2 cytokine pattern is present in the joints of patients with reactive arthritis (ReA), and whether the cytokine pattern can be modulated by cytokines or anticytokines. Methods. Eleven patients with ReA following infection with either Chlamydia trachomatis, Yersinia enterocolitica, or Salmonella enteritidis were investigated for the presence of Th1/Th2 cytokines in the joints. Release of the bacteria-specific cytokines interferon-γ (IFNγ), tumor necrosis factor α (TNFα), interleukin-10 (IL-10), and IL-4 was measured in synovial fluid mononuclear cells (SFMC) using enzyme-linked immunosorbent assay and polymerase chain reaction. In the synovial membrane, secretion of IFNγ and IL-4 was determined by immunohistologic analysis. Cytokine regulation was studied by adding cytokines and anticytokines to the cultures. Results. Upon stimulation with specific bacteria, SFMC secreted low amounts of IFNγ and TNFα, but high amounts of IL-10. IL-10 was responsible for the suppression of IFNγ and TNFα, as judged by the effect of adding either anti-IL-10 antibodies or exogenous IL-10 to these cultures. The addition of neutralizing anti-IL-12 to the cultures completely abolished the effects of anti-IL-10, suggesting that inhibition of the Th1-like cytokines by IL-10 is mediated through suppression of IL-12 synthesis. Exogenous IL-12 clearly enhanced IFNγ and TNFα secretion. In the synovial membrane, a higher number of cells were positive for the Th2 cytokine IL-4, compared with the amount of IFNγ-secreting cells. Conclusion. These data indicate that a Th2 cytokine pattern predominates in the joints of patients with ReA. Since Thl cytokines are necessary for the elimination of ReA-associated bacteria, Th2 cytokines might contribute to bacterial persistence in the joint. Therefore, the IL-10/IL-12 balance appears to be crucial for regulation of the cytokine pattern in the joints of patients with ReA.     

Differentiation of naive human CD4+ T cells into Th2 cells: The role of prostaglandin E2

T-helper (Th) 2 cells, which produce interleukin (IL)-4, IL-5, IL-10 and IL-13 upon stimulation of their T cell receptors, play an important role in the development of human allergic diseases. However, the precise mechanism involved in the differentiation of Th2 cells is not well understood compared with that of Th1 cells. The selective differentiation of Th1 or Th2 subsets is established during priming under the influence of a variety of factors. Prostaglandin E₂ (PGE₂) is one of those factors. Prostaglandin E₂ produced by antigen presenting cells directly affects the naive CD4⁺ T cells, causing them to differentiate into Th2 cells. This effect is mediated by the elevation of cyclic adenosine monophosphate (cAMP) at the early stage of T cell activation. IL-4 and PGE₂ lead naive CD4⁺ T cells to differentiate into Th2 cells cooperatively, by distinct signal transduction. Both PGE2 and IL-4 inhibit the hypomethylation of the proximal regulatory regions of the genomic IFN-γ gene, whose hypomethylation has been suggested as being important for the IFN-γ production by CD4⁺ T cells stimulated through their antigen receptors. Prostaglandin E₂ facilitates Th2 differentiation of naive CD4⁺ T cells by acting not only on T cells directly but also on antigen presenting cells by inhibiting their IL-12 production. The production of PGE₂ by monocytes is increased significantly in allergic patients. These results, taken collectively, suggest that PGE₂ plays an important role in facilitating the differentiation of Th2 cells in vivo.     

Shift toward T lymphocytes with a T helper 1 cytokine-secretion profile in the joints of patients with rheumatoid arthritis

Objective. To investigate whether T cells in the inflamed joints of patients with rheumatoid arthritis (RA) preferentially produce the T helper 1 (Th1) cytokines, interferon-γ (IFNγ) and interleukin-2 (IL-2), or the Th2 cytokine, IL-4, when compared with corresponding peripheral blood—derived T cells. Methods. Synovial fluid mononuclear cells (SFMC) and corresponding peripheral blood mononuclear cells (PBMC) from 10 patients with RA were analyzed, either directly or after in vitro stimulation, for the intracellular presence of Th1 and Th2 cytokines. The amount of secreted cytokine in the cell culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA). Results. IFNγ-containing cells were detected in the unstimulated SFMC, but not in the PBMC, of 3 patients with RA. Cells positive for IL-2 or IL-4 were not detected in the unstimulated samples. Following stimulation, the mean percentage of cells containing Th1 cytokines was significantly increased in the SFMC compared with the PBMC; no differences were found in the mean percentage of IL-4—containing cells. A comparable shift toward Th1 cytokines was observed when the amount of secreted cytokine was determined by ELISA. Conclusion. A shift toward T cells with a Th1 cytokine profile was observed in the joints of patients with RA. Since an imbalance between Th1 and Th2 cells is thought to be of pathogenic significance, this finding might have implications for the development of new therapies for RA.     

Human in vitro immune responses to Mycobacterium tuberculosis.

SETTING: T helper cells can be divided into 2 subsets on the basis of their cytokine generation. T helper 1 cells secreting gamma interferon and interleukin 2 appear to be more prominent in patients with limited tuberculous disease. OBJECTIVE: The purpose of this study was to evaluate human T helper cell immune responses to mycobacterial antigens in vitro and correlate these with the clinical features of patients with tuberculous infection or disease. DESIGN: We studied 51 subjects and 11 controls who were grouped according to disease involvement as follows: 1) Mantoux negative, BCG negative, no disease; 2) Mantoux positive, no disease; 3) localized extrapulmonary; 4) healed pulmonary; 5) active pulmonary; and 6) miliary/disseminated. Peripheral blood mononuclear cells were cultured with PHA, PPD or Tetanus Toxoid, proliferation assessed and the supernatant analysed using an ELISA for IFN gamma. ELISA was also used to measure M. tuberculosis specific antibodies in the serum. RESULTS: Mantoux size correlated with PPD proliferation r = 0.5, P = 0.005 and gamma IFN production r = 0.36, P < 0.01. All groups produced abundant gamma IFN although there was a trend toward higher production in groups 3 and 4. M. tuberculosis specific IgA (P = 0.003) and IgG1 (P = 0.002) was higher in groups 5 and 6. Those patients with limited disease (groups 2-4) had significantly lower levels of IgG4 than patients with severe disease (groups 5 & 6) (P < 0.02). CONCLUSION: In conclusion patients with healed or extrapulmonary disease have immune responses in vitro suggestive of a TH1 (cell mediated immune) response, whereas patients with miliary/disseminated disease have antibody production suggestive of a TH2 response, together with high gamma IFN production. Both TH1 and TH2 responses may be necessary for host protection if there is a high bacillary load.     

Pathophysiology of bronchial inflammation: chemoreceptors as therapeutic targets.

Asthma is an inflammatory disease characterized by reversible airway obstruction from a combination of bronchoconstriction and inflammatory changes including airway edema, infiltration of inflammatory cells such as eosinophils, mast cells, CD4+ T helper cells and monocyte/macrophages. Pharmacotherapy approaches include relievers of acute symptoms and controllers of inflammation. Inhaled corticosteroids are the sentinel therapy for asthma inflammation but are not always totally effective for a variety of reasons. With the increased understanding about the molecular basis for asthma inflammation, new therapies are emerging to target specific molecular networks, including antibodies against IgE and the TH2 cytokine IL-5; soluble IL-4 receptors and recombinant TH1 cytokines such as IL-12. Further, allergen immunotherapy for asthma is based upon its ability to change a TH2 to a TH1 response by inhibiting IL-4 and/or stimulating IFN gamma production. Although each of these modalities have their potential strengths and weaknesses, the approach offers a fresh attempt to better define the syndrome called asthma, show diversity of etiologies within even the same patient, and develop more effective, long lasting therapies for patients with this condition.     

Prostaglandin E2 exacerbates collagen‐induced arthritis in mice through the inflammatory interleukin‐23/interleukin‐17 axis

Objective

Recently, Th17 cells, a new subset of CD4+ T cells, emerged as major players in inflammation/autoimmunity. Maintenance of the Th17 phenotype requires interleukin‐23 (IL‐23), whereas the Th1‐promoting cytokine IL‐12p70 exerts a negative effect on Th17 cell differentiation. The lipid mediator prostaglandin E₂ (PGE₂) acts primarily as a proinflammatory agent in autoimmune conditions, through mechanisms that remain to be elucidated. The aim of this study was to investigate whether PGE₂ released in inflammatory foci activates resident dendritic cells (DCs) to express IL‐23 (at the expense of IL‐12) and IL‐6, resulting in a shift toward Th17 cell responses.

Methods

The effect of PGE₂ on IL‐23 production by DCs and subsequent induction of T cell–derived IL‐17 was assessed in vitro and in vivo. The effect of the stable PGE analog misoprostol was evaluated in a murine model of rheumatoid arthritis, in conjunction with IL‐23 and IL‐17 expression in affected joints and draining lymph nodes.

Results

In vivo administration of PGE₂ induced IL‐23–dependent IL‐17 production. Administration of misoprostol exacerbated collagen‐induced arthritis (CIA). CIA exacerbation was associated with increased levels of IL‐23p19/p40 messenger RNA and reduced expression of IL‐12p35, and with increased levels of the proinflammatory cytokines IL‐17, IL‐1β, IL‐6, and tumor necrosis factor in the affected joint. Following ex vivo restimulation, draining lymph node cells from misoprostol‐treated mice secreted higher levels of IL‐17 and lower levels of interferon‐γ.

Conclusion

Our results indicate that PGE₂ enhances DC‐derived IL‐6 production and induces a shift in the IL‐23/IL‐12 balance in favor of IL‐23, resulting in increased IL‐17 production, presumably through the amplification of self‐reactive Th17 cells.

     

Histone-specific Th0 and Th1 clones derived from systemic lupus erythematosus patients induce double-stranded DNA antibody production

Objective. To investigate whether histone-specific T helper (Th) cells that are able to induce anti-doublestranded DNA (anti-dsDNA) antibodies can be isolated from patients with systemic lupus erythematosus (SLE) and to characterize the cytokine secretion pattern of such Th clones. Methods. Peripheral blood mononuclear cells from SLE patients and healthy donors were stimulated with autologous apoptotic cell material or purified histones, expanded with interleukin-2 (IL-2), and cloned by limiting dilution. Histone reactivity of clones was examined by histone-specific proliferation and cytokine release. Cytokines were determined by enzyme-linked immunosorbent assay (ELISA) and CTLL-2 bioassay. Induction of anti-dsDNA antibodies was measured in cocultures of autologous B cells and Th clones by ELISA. Results. Numerous histone-specific T cell receptor (TCR) α/β+ Th clones were established from 2 of 3 patients with active SLE and from 1 of 2 healthy individuals. Most Th clones secreted IL-2, interferon-γ (IFNγ), and IL-4, whereas some produced predominantly IL-2 and lFNγ. Th clones that could stimulate the production of anti-dsDNA antibodies were derived from SLE patients and from a healthy individual. Conclusion. Th cells specific for histones may play an important role in the pathogenesis of SLE by inducing autoantibodies to dsDNA. Both Th1 and Th2 cytokines may be involved in the pathogenesis of SLE. The presence of histone-specific Th cells in a healthy individual indicates the importance of peripheral tolerance for preventing autoimmunity to nuclear antigens.     

High level of interleukin-10 production by the activated t cell population within the rheumatoid synovial membrane

Objective. To characterize the cytokine profile of the activated T cell population derived from the synovial membrane of rheumatoid arthritis (RA) patients. Methods. Interleukin-2 (IL-2) was used to select for in vivo–activated T cells from the synovial membrane of 2 patients with RA, and the cells were cloned nonspecifically. The cytokine production profile of these clones was compared with that of clones derived from peripheral blood monocytes (PBM) by stimulating all clones for 24 hours with immobilized anti-CD3 (coated at 10 μg/ml) or phorbol-12-myristate-13-acetate (10 ng/ml) plus soluble anti-CD3 (1 μg/ml). Interferon-γ (IFNγ), IL-4, and IL-10, the cytokines that discriminate between Th1 and Th2 cells and are involved in immunoregulation, were assayed by enzyme-linked immunosorbent assay. Results. There was a difference in the cytokines produced by the clones derived from the rheumatoid membranes compared with clones derived from the periphery. Clones derived from both membranes and PBM were mostly IFNγ-producers, i.e., either a Th0 or a Th1 profile. There was a high proportion of IFNγ/high IL-10-producing cells derived from the joint, but not from the periphery. Of clones derived from the synovial membrane of each of 2 RA patients, 100% and 50% produced both 1–10 ng/ml IFNγ and >7 ng/ml IL-10, compared with <7% of clones derived from normal or RA peripheral blood. In addition, when autologous membrane and PBM were compared, the mean concentration of IL-10 produced by the clones derived from the synovial membrane sample was significantly different from those produced by clones derived from peripheral blood (P < 0.02). Conclusion. The cytokine profile of the T cell clones that were obtained from the RA joint after expansion with IL-2 is distinct from that of the T cells that are predominant in PBM. This supports the concept that the T cell subsets that accumulate in the joint are not a random sample. The high level of IL-10 production by clones derived from the synovium suggests that this cytokine may be a major contributor to the endogenous immunosuppression that occurs in RA.     

Inhibition of Plasmodium falciparum growth in vitro by CD4+ and CD8+ T cells from non-exposed donors

T cells from most adult non-exposed donors, which express a memory phenotype (CD45RO+), can respond by proliferation to P. falciparum asexual stages in vitro. Such cells may have arisen from exposure to environmental organisms. To address the efficacy of such cells in eliminating parasites and investigate the mechanisms involved, we have used an in vitro assay where parasite growth can be precisely monitored in the presence of different cell preparations. Unfractionated peripheral blood mononuclear cells (PBMC) from both malaria-exposed and non-exposed donors inhibited parasite growth by up to 62% in a two day assay. Purified T cells in the presence of adherent cells had a similar effect, but purified T cells alone or adherent cells alone had minimal effect. Antigens released at the time of schizont rupture were maximally effective in stimulating interferon-γ (IFNγ) production. Neutralizing antibodies to IFNγ showed a partial reduction of growth inhibition in some individuals tested suggesting that different mechanisms may be operative. Neutralizing antibody to TNFα had a partial effect in combination with anti-IFNγ. Antibodies to IL-1 and IL-4 had no effect. T cell fractionation experiments showed that while purified CD4⁺ T cells from some donors produced IFNγ and inhibited parasite growth, purified CD8⁺ T cells could inhibit parasite growth to a greater extent without production of detectable IFNγ. Four parasitised red blood cell clones (CD4⁺, TCRαβ⁺, IFNγ producing) derived from non-exposed donors inhibited parasite growth to comparable levels, but one clone showed low production of IFNγ whilst the other three produced high levels. Our data show that T cells from non-exposed donors have the potential to eliminate malaria parasites via non-IFNγ dependent mechanisms. Such mechanisms may contribute to a degree of innate resistance to malaria in vivo, and may be able to be targeted by malaria vaccine programs.     

A critical role for IL-21 receptor signaling in the pathogenesis of systemic lupus erythematosus in BXSB-Yaa mice

Interleukin 21 (IL-21) is a pleiotropic cytokine produced by CD4 T cells that affects the differentiation and function of T, B, and NK cells by binding to a receptor consisting of the common cytokine receptor γ chain and the IL-21 receptor (IL-21R). IL-21, a product associated with IL-17-producing CD4 T cells (T_H17) and follicular CD4 T helper cells (T_FH), has been implicated in autoimmune disorders including the severe systemic lupus erythematosus (SLE)-like disease characteristic of BXSB-Yaa mice. To determine whether IL-21 plays a significant role in this disease, we compared IL-21R-deficient and -competent BXSB-Yaa mice for multiple parameters of SLE. The deficient mice showed none of the abnormalities characteristic of SLE in IL-21R-competent Yaa mice, including hypergammaglobulinemia, autoantibody production, reduced frequencies of marginal zone B cells and monocytosis, renal disease, and premature morbidity. IL-21 production associated with this autoimmune disease was not a product of T_H17 cells and was not limited to conventional CXCR5⁺ T_FH but instead was produced broadly by ICOS⁺ CD4⁺ splenic T cells. IL-21 arising from an abnormal population of CD4 T cells is thus central to the development of this lethal disease, and, more generally, could play an important role in human SLE and related autoimmune disorders.     

Proinflammatory T helper type 17 cells are effective B-cell helpers

T helper type 17 (TH17) cells are highly proinflammatory effector T cells that are characterized by the production of high amounts of IL-17A, IL-17F, IL-21, and IL-22. Furthermore, TH17 cells have been associated with a number of autoimmune diseases. However, it is not clear whether TH17 cells can also serve as effective helper cells. Here we show that TH17 cells can function as B-cell helpers in that they not only induce a strong proliferative response of B cells in vitro but also trigger antibody production with class switch recombination in vivo. Transfer of TH17 cells into WT or T-cell receptor α–deficient mice, which lack endogenous T cells, induces a pronounced antibody response with preferential isotype class switching to IgG1, IgG2a, IgG2b, and IgG3, as well as the formation of germinal centers. Conversely, blockade of IL-17 signaling results in a significant reduction in both number and size of germinal centers. Whereas IL-21 is known to help B cells, IL-17 on its own drives B cells to undergo preferential isotype class switching to IgG2a and IgG3 subtypes. These observations provide insights into the unappreciated role of TH17 cells and their signature cytokines in mediating B-cell differentiation and class switch recombination.     

Th1 and Th17 cell subpopulations are enriched in the peripheral blood of patients with systemic juvenile idiopathic arthritis

Objective. The role of the adaptive immune system has not been explored in detail compared with the innate immune system in systemic JIA (sJIA) pathogenesis. The aim of this study was to examine the phenotype of circulating peripheral blood CD4(+) T-cell subpopulations in a cross-sectional study of sJIA patients during disease remission on medication and during acute flare of the disease. Methods. Flow cytometry was used to examine the phenotype and cytokine production of IFNγ-, IL-4- and IL-17-producing CD4(+) T cells in the peripheral blood of 10 sJIA patients with active disease, 9 sJIA with inactive disease, 14 JIA patients with oligoarticular onset, 10 adult control subjects and 10 age-matched control subjects. In parallel, we examined the proportion of FoxP3(+) Tregs. Results. IFNγ- and IL-17-producing CD4(+) T cells and IL-17-producing CD3(+)CD4(-) T cells were present at higher proportions in the peripheral blood of sJIA patients, irrespective of their disease status. Our data also confirm the known increase of the proportions of IFNγ-producing Th1 cells with increasing age and suggest an increase with age in the IL-17-producing CD4(+) T-cell population. Conclusion. This study is the first to describe significantly higher proportions of Th1 and Th17 T helper cell subsets in the peripheral blood of sJIA patients. These proinflammatory cells may play a pathogenic role in sJIA. Our data also emphasize the importance of using paediatric age-matched control subjects when evaluating the T-cell cytokine profile in JIA.