Cellular mRNA expression of interferon-gamma (IFN-γ), IL-4 and transforming growth factor-beta (TGF-β) in rats nasally tolerized against experimental autoimmune myasthenia gravis (EAMG)

Nasal administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with AChR plus Freund's complete adjuvant (FCA) resulted in prevention or marked decrease of the severity of EAMG, suppression of AChR-specific B cell responses and of AChR-reactive T cell functions. To examine the involvement of immunoregulatory cytokines and the underlying mechanisms involved in tolerance induction, in situ hybridization with radiolabelled synthetic oligonucleotide probes was adopted to enumerate mononuclear cells (MNC) expressing mRNA for the proinflammatory cytokine IFN-γ, the B cell stimulating IL-4 and the immune response-down-regulating TGF-β. Popliteal and inguinal lymph nodes from EAMG rats contained elevated numbers of AChR-reactive IFN-γ, IL-4 and TGF-β mRNA-expressing cells compared with control rats receiving PBS nasally and injected with FCA only. Nasal tolerance to EAMG was accompanied by decreased numbers of AChR-reactive IFN-γ and IL-4 mRNA-expressing cells, and strong up-regulation of TGF-β mRNA-positive cells in lymphoid organs compared with non-tolerized EAMG control rats. The relative affinity of anti-AChR antibodies was lower, but muscle AChR amounts were higher in nasally tolerized rats compared with non-tolerized EAMG control rats. The results suggest that IFN-γ and IL-4 are central effector molecules in the development of EAMG, and that TGF-β plays an important role in tolerance induction to EAMG.     

Increased levels of interferon-gamma (IFN-gamma), IL-4 and transforming growth factor-beta (TGF-beta) mRNA expressing blood mononuclear cells in human HIV infection.

Evidence has been presented for the involvement of IFN-gamma, IL-4 and TGF-beta in AIDS. Measured plasma levels may, however, poorly reflect in vivo production, since cytokines act auto- and paracrinally and have very short half life in plasma. In situ hybridization with complementary DNA oligonucleotide probes was used to enumerate blood mononuclear cells expressing cytokine messenger RNA (mRNA). HIV-infected patients had elevated blood levels of cells expressing each of the cytokines, with predominance for cells expressing TGF-beta mRNA. All AIDS patients included had elevated numbers of IL-4 mRNA-expressing cells, and levels of cells expressing this cytokine correlated inversely with counts of CD4+ cells in blood, reflecting the involvement of Th2-like cells in later stages of HIV infection. The described approach should be useful in further studies of cytokines in HIV infection and other diseases.     

类风湿性关节炎患者滑膜液中IL-10、IL-12和sFasL含量的检测

为了研究细胞因子和凋亡分子在类风湿性关节炎(RA)发病中的作用,用ELISA法分析了26例RA患者滑膜液和血清中IL-12、IL-10和可溶性FasL(sFasL)的含量。结果表明RA患者滑膜液中IL-12、IL-10含量分别为(419.9±89.2)pg/ml和(187.7±34.5)pg/ml,外周血中这两种细胞因子的含量均较低,分别为(65.3±34.2)pg/ml(IL-12)和(85.0±12.7)pg/ml(IL-10)。滑膜液中sFasL的含量为266pg/ml,明显高于血清含量(36pg/ml)。这一结果提示,RA患者滑膜液中IL-12含量和sFasL增高,这些炎性细胞因子增高可能参与了关节滑膜中的自身反应性T细胞的活化,继而造成免疫损伤。     

Dynamic expression of transforming growth factor-betas (TGF-β) and their type I and type II receptors in the synovial tissue of arthritic rats

A well characterized animal model that shares many characteristic features with rheumatoid arthritis (RA) is collagen-induced arthritis (CIA) in DA rats. Recent studies have demonstrated that TGF-β, a multifunctional cytokine, is an important modulator of the immune response in CIA, and possibly also in RA. In this study we have investigated the expression of the precursor forms of TGF-β1, TGF-β2, TGF-β3, as well as TGF-β type I receptor (TGF-βRI) and TGF-β type II receptor (TGF-βRII) in the synovial tissue of arthritic rats during the course of the disease. By using immunohistochemical techniques, an abundant expression of all three TGF-β isoforms and their receptors was observed in the arthritic synovia, an expression that increased with time after onset of disease. Antibodies to TGF-β1, TGF-β2, TGF-βRI and TGF-βRII stained blood vessels intensively, already at the early onset of inflammation, whereas the synovial lining layer and chondrocytes expressed strong immunoreactivity later on in the inflammatory process. The most intense staining with these antibodies was detected in fibroblasts within fibrotic tissue, in particular at the cartilage–pannus junction. Interestingly, TGF-β3 only stained macrophage-like cells and chondrocytes in the synovia. The data suggest that the abundant expression of TGF-β1, TGF-β2, TGF-β3 as well as TGF-βRI and TGF-βRII in the synovia, is of pathogenic importance in the development of CIA, although the question of how the different TGF-β isoforms may enhance or counteract different arthritogenic events remains open.     

Hypoxia augments cytokine (transforming growth factor-beta (TGF-β) and IL-1)-induced vascular endothelial growth factor secretion by human synovial fibroblasts

Vascular endothelial growth factor (VEGF) is abundant in synovium and synovial fluids, where it probably contributes to vascular permeability and angiogenesis in arthritic joints. To investigate the probable sources of VEGF in synovium, we compared the ability of several cytokines (TGF-β, platelet-derived growth factor (PDGF), IL-1, tumour necrosis factor (TNF), basic fibroblast growth factor (bFGF) that are associated with arthritis and angiogenesis, to stimulate secretion of VEGF protein by human synovial fibroblasts. TGF-β was the strongest inducer of VEGF secretion; six times more VEGF was secreted when cells were stimulated by TGF-β than when stimulated by PDGF or IL-1 for 24 h. TNF-α and bFGF did not stimulate any secretion of VEGF. The stimulatory effects of TGF-β and IL-1 on VEGF secretion were additive. Hypoxic culture alone also stimulated VEGF secretion, but more importantly, hypoxic culture conditions doubled the rate of VEGF secretion stimulated by the cytokines TGF-β and IL-1. When dermal and synovial fibroblasts were stimulated identically by hypoxia and cytokines (TGF-β and IL-1), synovial fibroblasts secreted four times more VEGF than did dermal fibroblasts. Thus in rheumatoid arthritis, the capacity of synovial fibroblasts in the hypoxic environment to secrete large amounts of VEGF in response to cytokines such as TGF-β probably contributes significantly to angiogenesis in the synovium.     

Transforming growth factor-beta 1 (TGF-β1)-mediated inhibition of glial cell proliferation and down-regulation of intercellular adhesion molecule-1 (ICAM-1) are interrupted by interferon-gamma (IFN-γ)

We utilized a model of myelin basic protein (MBP) activation in vivo and MBP-stimulated cultures in vitro to study the influence of TGF-β1 on glial cell proliferation and ICAM-1/leucocyte function-associated antigen-1 (LFA-1) expression, and to observe the antagonistic effects of TGF-β1 and IFN-γ. TGF-β1 inhibited MBP-stimulated and MBP-activated glial cell proliferation, especially in MBP-stimulated separated microglia and astrocytes, and down-regulated the expression of ICAM-1 on MBP-stimulated glial cells and separated microglia. ICAM-1 expression on MBP-activated glial cells was intensely suppressed, whereas its expression on MBP-stimulated astrocytes was not influenced. TGF-β1 had no effect on LFA-1 expression. In contrast, IFN-γ up-regulated ICAM-1 expression, but inhibited proliferative response on MBP-stimulated glial cells when cultured without TGF-β1. Examination of TGF-β1 and IFN-γ interactions revealed that TGF-β1-mediated inhibition of proliferation and down-regulation of ICAM-1 on glial cells were prevented by IFN-γ. The suppressive effect was re-established with high doses of TGF-β1 in cultures, indicating that biological effects of TGF-β1 vary depending on nitric oxide (NO) production, its concentration in the microenvironment and regulation of the cytokine network.     

High numbers of autoantigen-reactive mononuclear cells expressing interferon-gamma (IFN-gamma), IL-4 and transforming growth factor-beta (TGF-beta) are present in cord blood.

Umbilical cord blood of neonates and peripheral blood of healthy adults were analysed by in situ hybridization for numbers of mononuclear cells (MNC) expressing the cytokines IFN-gamma, TGF-beta and IL-4 mRNA without culture and after culture in the presence of acetylcholine receptor (AChR), myelin basic protein (MBP) and peripheral myelin protein P2. These antigens were chosen since they represent autoantigens in putatively immune-mediated neurological diseases. The numbers of cells expressing cytokine mRNA after 72 h culture in the presence of AChR, MBP and P2 were higher in cord blood than in peripheral blood of healthy adults. IFN-gamma, TGF-beta and IL-4 were always elevated in parallel. In cord blood there was a pronounced reactivity to several of the tested antigens, while such broad reactivity was not found in peripheral blood of healthy adults. No differences in cytokine mRNA expression were found between cord blood and peripheral blood of adults when cells were analysed without culture. The results show a capacity of cord blood cells to react to several autoantigens by the up-regulation of cytokine mRNA expression.     

Cellular mRNA expression of interferon-gamma, IL-4 and transforming growth factor-beta (TGF-beta) by rat mononuclear cells stimulated with peripheral nerve myelin antigens in experimental allergic neuritis.

Experimental allergic neuritis (EAN) serves as a useful model for inflammation in the peripheral nervous system. To study the potential role of important immunoregulatory and effector cytokines in EAN, we examined the expression of mRNA for interferon-gamma (IFN-gamma), IL-4 and TGF-beta by in situ hybridization in lymph node and splenic cells cultured with bovine peripheral nerve myelin (BPM), P2 and P0 during the course of EAN in Lewis rats. Levels of IFN-gamma mRNA-expressing mononuclear cells (MNC) from lymph nodes and spleens roughly correlated with clinical status, consistent with a disease-promoting role for IFN-gamma. BPM, P0 and P2-reactive IFN-gamma mRNA-expressing T cells appeared in lymph nodes and spleen before onset of the disease, whereas a significant TGF-beta response to BPM, P2 and P0 was observed at lower levels than the IFN-gamma response and at onset of recovery, consistent with a disease down-regulating role of TGF-beta. IL-4 mRNA-expressing cells were found at levels similar to TGF-beta mRNA-expressing cells, and with the latest peak of the three cytokines examined. This result suggests that IL-4 may also suppress IFN-gamma expression at late recovery phase of EAN.     

Expression of vascular endothelial growth factor by synovial fluid neutrophils in rheumatoid arthritis (RA)

Most of the leucocytes infiltrating rheumatoid synovial fluid (SF) are neutrophils capable of producing a variety of inflammatory mediators known to contribute significantly to the disease process during active RA. In the present study, we investigated the contribution made by SF neutrophils to the elevated levels of vascular endothelial growth factor (VEGF) seen in rheumatoid SF. Rheumatoid SF neutrophils were found to contain significantly larger amounts of both VEGF protein and its mRNA than peripheral blood neutrophils from either RA patients or healthy controls. Levels of cell-associated VEGF were well correlated with free VEGF in SF, which was significantly higher than in SF from osteoarthritis patients. Levels of SF neutrophil-associated VEGF also correlated with RA disease activity and cell surface integrin expression. Thus, SF neutrophil-associated VEGF may be considered an indicator of both local and systemic inflammation of RA, contributing to the neovascularization seen during RA synovitis.     

Differential inhibitory effects of indomethacin,dexamethasone, and interferon-gamma (IFN-γ) on IL-11 production by rheumatoid synovial cells

IL-11, a member of the IL-6 type cytokines, has some biological activity related to the joint destruction in rheumatoid arthritis (RA), such as induction of osteoclast differentiation. However, its expression and regulation in rheumatoid inflamed joints has not been clarified. In the present study we examined the capacity of fresh rheumatoid synovial cells (fresh RSC) to produce IL-11, and the effect of indomethacin, dexamethasone and IFN-γ on IL-11 production. Fresh RSC obtained from eight patients with RA produced large amounts of IL-11, measured by ELISA, and showed strong expression of IL-11 mRNA, determined by Northern blotting. Indomethacin inhibited the production of IL-11 by about 55%. Prostaglandin E₂ (PGE₂) completely prevented the inhibition, suggesting that IL-11 production by fresh RSC was in part mediated by PGE₂. Dexamethasone inhibited the production of IL-11 by more than 80%. Interestingly, the inhibition was not abolished by PGE₂. IFN-γ inhibited the production of IL-11 from IL-1α-stimulated cultured rheumatoid synovial fibroblasts, although IFN-γ did not inhibit the production of IL-11 by fresh RSC. These results suggest that the production of IL-11 by rheumatoid synovia was differentially regulated by PGE₂ and IFN-γ, and that treatment with indomethacin or dexamethasone decreased the level of IL-11 at inflammatory joints in patients with RA.     

Release of transforming growth factor-beta (TGF-β) and fibronectin by alveolar macrophages in airway diseases

Asthma and chronic bronchitis are associated with airway remodelling, and airway macrophages are present in bronchial inflammation. TGF-β and fibronectin released by alveolar macrophages possess a fibrogenic potency. The potential role of alveolar macrophages in airway remodelling was studied in asthma and chronic bronchitis by the release of TGF-β and fibronectin. Alveolar macrophages were isolated by bronchoalveolar lavage in 14 control subjects, 14 asthmatics and 14 chronic bronchitics. The spontaneous and lipopolysaccharide (LPS)- or concanavalin A (Con A)-induced release of TGF-β and fibronectin was measured by ELISA. Alveolar macrophages from chronic bronchitics spontaneously release greater amounts of TGF-β and fibronectin than those from asthmatic and control subjects. Alveolar macrophages from asthmatics release greater amounts of TGF-β and fibronectin than those from control subjects. The spontaneous release of TGF-β is significantly correlated with that of fibronectin. Fibronectin release was significantly reduced after LPS stimulation, and TGF-β release was significantly increased after LPS stimulation, except in chronic bronchitis patients. Con A increased the release of TGF-β in cells from normal subjects. This study suggests that activated macrophages play a role in airway remodelling in chronic bronchitis and to a lesser extent in asthma.     

Th1 (IL-2, interferon-gamma (IFN-γ)) and Th2 (IL-10, IL-4) cytokine production by peripheral blood mononuclear cells (PBMC) from patients with systemic lupus erythematosus (SLE)

We investigated the production of IL-2, IFN-γ, IL-10 and IL-4 by PBMC from 24 patients with SLE and 10 healthy individuals. Basal and mitogen-stimulated (lipopolysaccharide and phytohaemagglutinin (LPS + PHA)) cytokine production was determined in a whole blood assay (WBA). Supernatants were collected and assayed with specific ELISAs. Although the IL-2 and IFN-γ contents did not differ significantly between patients and controls under both conditions, statistically significant correlations were found between each cytokine and disease activity (SLAM index) after stimulation (respectively, r= 0.501, P = 0.01 and r = 0.631, P = 0.001). PBMC IL-10 production was significantly higher for patients than controls (P = 0.05), but no correlation between IL-10 levels and the SLAM index was obtained. IL-4 production was not statistically different between SLE patients and controls. For stimulated WBAs, the IL-10/IL-2 and IL-10/IFN-γ ratios were significantly correlated with disease severity (P = 0.02; P = 0.001, respectively). Overall, our data suggest that SLE is characterized by an elevated production of IL-10, reflecting the basal state of activation of the immune system. During exacerbation of SLE, IL-2 and IFN-γ are synthesized in larger amounts and may cause the tissue damage observed.     

Chronic mucocutaneous candidiasis. I. Altered antigen-stimulated IL-2, IL-4, IL-6 and interferon-gamma (IFN-γ) production

Patients with chronic mucocutaneous candidiasis (CMC) present with persistent infections with the opportunistic yeast Candida. Impaired cell-mediated responses to Candida have been documented in CMC patients, but the defect remains poorly understood. The importance of Th1 cytokines in resistance and Th2 in susceptibility to Candida infections has recently been demonstrated in murine models. In our studies we evaluated production of IL-2 and IFN-γ (markers of Th1 type responses) as well as IL-4 and IL-6 (Th2 type markers) following stimulation with two kinds of Candida antigens (CAgs), polysaccharide antigens, tetanus toxoid and pokeweed mitogen. Our results demonstrate that CMC patients have impaired cytokine production upon in vitro stimulation with CAgs resulting in low or absent IL-2, increased IL-6 and either absent or increased IFN-γ production. Cytokine production following stimulation by other antigens was unaltered. The overall cytokine-producing capacity assessed through mitogen stimulation was also intact. Addition of IFN-α or IFN-γ to culture in an attempt to modify cytokine production did not have significant effects. Levels of soluble IL-6 receptors were not increased and could not account for increased IL-6 production. Our studies support the hypothesis that Candida antigens trigger a predominantly Th2 instead of a Th1 cytokine response in patients with CMC.     

Immunocytochemical localization of inducible nitric oxide synthase and transforming growth factor-beta (TGF-β) in leprosy lesions

Inducible nitric oxide synthase (iNOS) and TGF-β were localized by immunocytochemistry in skin lesions from patients across the leprosy spectrum, and from patients undergoing reversal reaction. iNOS expression was highest at the tuberculoid pole of the spectrum, and increased during reversal reaction. TGF-β was observed throughout the leprosy spectrum, but was highest at the lepromatous pole. Levels of TGF-β decreased during reversal reaction. Reduced levels of TGF-β may contribute to unregulated inflammatory responses during reactional episodes.     

The role of IL-12 in inflammatory activity of patients with rheumatoid arthritis (RA)

The aim of this study was to investigate the role of IL-12 in patients with RA. IL-12 (p70) and its associated cytokines were measured in sera and synovial fluid (SF) using an enzyme-linked immunosorbent method. Seven American College of Rheumatology (ACR) core set measures as well as IL-12 levels were sequentially monitored at the commencement and 4 months after treatment with a low-dose steroid and disease-modifying anti-rheumatic drugs (DMARDs). In sera, 64 (42.2%) of 152 RA patients had detectable concentrations of IL-12 (p70), whereas one (1.4%) of 69 osteoarthritis (OA) patients and five (10%) of 50 healthy controls had detectable IL-12 (P < 0.001). The median level of circulating IL-12 was also higher in RA patients (P < 0.001). In SF, the number of patients with detectable IL-12 and the median IL-12 levels were significantly higher in RA patients (n = 53) than in OA patients (n = 22). In paired samples (n = 53) of sera and SF from RA patients, IL-12 levels were higher in the SF than in sera (P < 0.001). Patients with detectable IL-12 (n = 51) in sera had higher tender joint scores (P = 0.003), swollen joint scores (P < 0.001) and C-reactive protein (CRP; P = 0.036), than those without (n = 55). Four months after treatment with DMARDs, the improved group showed a larger IL-12 decrease than the non-improved group (P = 0.017). The levels of IL-12 correlated positively with those of IL-2, interferon-gamma, IL-6, and tumour necrosis factor-alpha, but were correlated inversely with those of IL-10. Our results demonstrate that IL-12 levels reflect RA disease activity and that IL-12 is involved in the production of proinflammatory cytokines. An IL-12 blockade could be useful for the treatment of RA.     

Persistent production of interferon-gamma (IFN-γ) and IL-12 is essential for the generation of protective immunity against Listeria monocytogenes

IFN-γ and IL-12 are believed to be important in the host defence against Listeria infection in mice. However, the relationship between these two cytokines and generation of protective immunity remains poorly understood. In the present study, it was found that at least 4 days of immunizing infection were required for the generation of protective immunity against L. monocytogenes. Protective immunity was generated only by immunizing infection with virulent strain. Even repeated injections of avirulent strain failed to induce protective immunity. When the immunizing infection was terminated with antibiotics, generation of protective immunity and IFN-γ-producing ability was impaired, while expression of IFN-γ and IL-12 was also impaired. The mutual relationship between IFN-γ and IL-12 in L. monocytogenes infection was analysed in vitro. After neutralization of IL-12, IFN-γ production was completely blocked and IFN-γ expression was also inhibited. In contrast, there was no change of IL-12 expression after neutralization of IFN-γ. Taking all facts into consideration, it may be concluded that persistent production of IFN-γ induced by persistent production of IL-12 during immunizing infection is essential for the generation of protective immunity against L. monocytogenes.     

Proliferation and production of interferon-gamma (IFN-γ) and IL-4 in response to Staphylococcus aureus and Staphylococcal superantigen in childhood atopic dermatitis

We have examined the cell-mediated immunity (CMI) to Staphylococcus aureus(S. aureus) and Staphylococcal enterotoxin B (SEB) in peripheral blood mononuclear cells (PBMC) from children with atopic dermatitis (AD) and from non-atopic child controls by measurement of proliferative responses and production of the cytokines IFN-γ and IL-4. PBMC from children with AD showed significantly higher proliferative responses to both S. aureus (P <0.01) and SEB (P < 0.05). Despite this enhanced proliferation, production of IFN-γ in response to S. aureus (P <0.001) and SEB (P < 0.01) from these PBMC was significantly diminished. In contrast, PBMC from children with AD were significantly more likely to produce IL-4 in response to S. aureus (P < 0.01). These findings demonstrate in vitro heightened CMI to S. aureus in children with AD, and implicate S. aureus as a potent inflammatory stimulant. Impaired IFN-γ production to S. aureusin vivo may result in failure to eradicate S. aureus from skin. The organism's persistence on skin would contribute to inflammation by causing continued T cell activation and release of pro-inflammatory mediators.