Synthesis and regulation of accessory/proinflammatory cytokines by intestinal epithelial cells.

Intestinal epithelial cells (IEC) have been shown to act as antigen-presenting cells (APC) in vitro and may have this capacity in vivo. In order to determine whether IEC, like other APC, are able to produce accessory cytokines which may play a role in T cell activation, we assessed the accessory cytokine profile of IEC constitutively or after stimulation. We measured expression, production and regulation of accessory cytokines (IL-1 beta, IL-6, tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) by the presence of mRNA as well as secreted protein. Freshly isolated IEC from surgical specimens were cultured in the presence or absence of lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), IL-1 beta or TNF-alpha. mRNA was assessed by a specific RNAse protection assay which controlled for contaminating cell populations while protein secretion was measured by ELISA (IL-1) or bioassay (TNF and IL-6). Neither IL-1 beta nor TNF-alpha were detectable in cultured IEC supernatants, supporting the lack of macrophage contamination. All IEC spontaneously secreted IL-6 at levels comparable to those of macrophages. IEC IL-6 mRNA also increased approximately 200-fold during the first 24 h of culture. LPS, IFN-gamma or TNF-alpha had no effect on spontaneous IL-6 production, and neither resulted in the secretion of IL-1 beta or TNF-alpha. However, IL-1 beta up-regulated IL-6 synthesis by 6-7-fold. IEC express a profile of cytokine mRNAs distinct from conventional APC (low level constitutive IL-6 expression but no detectable IL-1 beta, TGF-beta or TNF-alpha), adding to their uniqueness as APC.     

Cytokine regulation of intercellular adhesion molecule-1 (ICAM-1) expression on human glioblastoma cells

Intercellular adhesion molecule-1 (ICAM-1) has recently been identified as one of the ligands for lymphocyte function-associated antigen-1 (LFA-1). Immunohistochemical staining of frozen tissue sections using the ICAM-1 antibody RR1/1 demonstrated significant levels of ICAM-1 expression on human glioblastoma cells and on intratumoural vascular endothelial cells. ICAM-1 was weakly expressed or absent from low grade gliomas and absent from normal and fetal brain. ICAM-1 expression was similar to that of MHC class II. HLA-DR antigens. Glioblastoma cell lines constitutively expressed ICAM-1 to a minimal or moderate extent. Surface antigen expression of ICAM-1 and ICAM-1-specific mRNA could be significantly increased by incubating glioblastoma cells with interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma). IL-2, IL-4, IL-6 and transforming growth factor beta 2 (TGF-beta 2) had no significant effect on surface antigen expression. Significant enhancement of ICAM-1 expression was obtained using TNF-alpha and IL-1 beta at 1-10 U/ml and at 500 U/ml of IFN-gamma. Induction of ICAM-1 specific mRNA was observed 4 h after cytokine treatment and decreased by 24 h. Surface antigen expression of ICAM-1 increased for up to 48 h after treatment.     

Expression patterns of cytokines and chemokines genes in human hepatoma cells

Various cytokines and chemokines play a role in carcinogenesis. However, no study has previously been undertaken to investigate comprehensively the expressions of cytokines and chemokines in hepatoma cells. In this study, we determined which cytokines and chemokines are expressed in hepatoma cells. Recently, it was reported that the expressions of several chemokines could be increased by Fas stimulus in many normal and cancer cells. Therefore, we also investigated whether chemokines expression is regulated by Fas ligation. To address this issue, we performed RNase protection assays upon 13 cytokines and 8 chemokines genes in 10 human hepatoma cell lines, comprising 8 hepatitis B virus (HBV)-associated hepatoma cell lines. Transforming growth factor-beta2 (TGF-beta2) was found to be expressed in 8 HBV-associated hepatoma cell lines, and to be potently expressed in 5 cell lines; however, the mRNA expressions of interleukin-10 (IL-10), IL-12, interferon-gamma(IFN-gamma) and tumor necrosis factor-alpha(TNF-alpha) were not detected in any cell lines examined. Among the chemokines investigated in this study, IL-8 was expressed by 8 HBV- associated hepatoma cell lines, and monocyte chemoattractant protein-1 (MCP-1) by 7 HBV-associated hepatoma cell lines. However, the mRNA expressions of macrophage inflammatory protein-1alpha(MIP-1alpha), MIP-1beta, interferon-inducible protein-10 (IP-10), RANTES, lymphotactin and I-309 were either very weak or undetectable. Fas ligation did not increase chemokines expression in hepatoma cells. Conclusively, TGF-beta2, IL-8 and MCP-1 were overexpressed in HBV-associated hepatoma cells, and the expressions of chemokines were not increased by Fas ligation in human hepatoma cells.     

Interferon-gamma, tumor necrosis factor-alpha, and interleukin 1-beta suppress the replication of hepatitis B virus through oxidative stress

The effect of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin 1-beta (IL-1beta), and H2O2, on hepatitis B virus (HBV) replication was analyzed in the HBV DNA transfected human hepatoblastoma-derived cell line HB 611. Secretion of HBV DNA from HB611 cells was inhibited by IFN-gamma, TNF-alpha, IL-1beta, and H2O2 in a dose-dependent manner. These cytokines and H2O2 also decreased HBV mRNA expression in HB611 cells, meaning that these reagents decreased the synthesis of all virally encoded components of the HBV virion. The level of manganese-SOD mRNA, indicative of occurrence of oxidative stress, increased immediately after treatment with IFN-gamma, TNF-alpha, IL-1beta, and H2O2. Moreover, the antioxidant N-acetyl-L-cysteine substantially inhibited the antiviral effect. Our findings suggest that oxidative stress may be a common factor in the antiviral effects of IFN-gamma, TNF-alpha, and IL-1beta on HBV.     

Expression of cytokines and inducible nitric oxide synthase mRNA in the lungs of mice infected with Cryptococcus neoformans: effects of interleukin-12.

We have recently established a murine model of pulmonary and disseminated infection with a highly virulent strain of Cryptococcus neoformans and demonstrated that administration of interleukin-12 (IL-12) protected the animals against infection. In this study, we extended these studies by investigating the host defense mechanisms. In particular, we examined the expression of mRNA for helper T-cell 1 (Th1) cytokines (IL-2, lymphotoxin, and gamma interferon [IFN-gamma]), Th2 cytokines (IL-4, -6, and -10), macrophage-derived cytokines (tumor necrosis factor alpha [TNF-alpha], IL-1beta, transforming growth factor beta [TGF-beta, IL-12p40, and IFN-gamma-inducing factor [IGIF]), and inducible nitric oxide synthase (iNOS) in the lungs on days 1, 3, 7, and 14 after infection and following treatment with IL-12. There was little or no expression of mRNAs for Th1 cytokines, TNF-alpha, IL-12p40, IGIF, and iNOS in the infected mice, but expression increased markedly after treatment with IL-12. In contrast, the mRNAs for Th2 cytokines, IL-1beta, and TGF-beta were detected at considerable levels during the early stages of infection, and, interestingly, expression was not suppressed by IL-12 but rather augmented, particularly during the late stage. Similar results were also obtained for IFN-gamma, IL-4, IL-10, and TNF-alpha measured in the lung homogenates by enzyme-linked immunosorbent assay. These results suggest that the predominance of expression of Th2 cytokines and TGF-beta over Th1 cytokines, TNF-alpha, IL-12p40, IGIF, and iNOS is associated with severe lethal infection in mice and that administration of IL-12 protects infected animals by stimulating Th1 cytokines.     

Transforming growth factor-beta 1 primes macrophages for enhanced expression of the nitric oxide synthase gene for nitric oxide-dependent cytotoxicity against Entamoeba histolytica.

Nitric oxide (NO) produced by activated macrophages is the major cytotoxic molecule for in vitro cytotoxicity against Entamoeba histolytica trophozoites. Transforming growth factor-beta 1 (TGF-beta 1) is a potent negative regulator of several macrophage functions, including NO production. In this study, we investigated the effect of TGF-beta 1 on macrophage nitric oxide synthase (mac-NOS) mRNA expression and NO production for macrophage cytotoxicity against E. histolytica trophozoites. TGF-beta 1 by itself was incapable of inducing mouse bone marrow-derived macrophage (BMM) amoebicidal activity and NO production (as measured by nitrite). In contrast, TGF-beta 1 pretreatment (4 hr) primed BMM for an enhanced amoebicidal activity of 15% and 23% in response to (interferon-gamma) IFN-gamma+tumour necrosis factor-alpha (TNF-alpha) or IFN-gamma+lipopolysaccharide LPS, concomitant with increased NO production of 85% and 27%, respectively. TGF-beta 1 pretreatment increased NO production in response to IFN-gamma+TNF-alpha/LPS stimulation in a time- and dose-dependent manner. By Northern blot analysis, the increased NO production of TGF-beta 1-pretreated BMM was preceded by markedly enhanced expression of mac-NOS mRNA. The priming effect of TGF-beta 1 on NO production was critically dependent on both a TNF-alpha (> or = 100 U) and a LPS (> or = 100 ng) triggering dose in the presence of IFN-gamma. TGF-beta 1 pretreatment enhanced TNF-alpha mRNA expression, but had no effect on TNF-alpha production in culture supernatants after 4 hr of stimulation with IFN-gamma+TNF-alpha/LPS; however, at a later time-point (16-48 hr), even though the levels of TNF-alpha mRNA expression were unaffected, TNF-alpha production was reduced. These data demonstrate that TGF-beta 1 priming for increased mac-NOS mRNA expression for NO-dependent cytotoxicity against E. histolytica in response to IFN-gamma+TNF-alpha/LPS stimulation may be involved in the modulation of a TNF-alpha triggering signal by TGF-beta 1.     

TH2 Cytokine-enhanced and TGF-beta-enhanced vascular endothelial growth factor production by cultured human airway smooth muscle cells is attenuated by IFN-gamma and corticosteroids

BACKGROUND: T(H)2 and T(H)1 cytokines have opposite effects on many aspects of the inflammatory response. METHODS: This study was designed to determine if cytokines possibly present in asthma can modulate airway smooth muscle cell (ASMC) production of vascular endothelial growth factor (VEGF) and thus contribute to altered airway vascularity. ASMC were incubated for 24 hours with various concentrations of T(H)2 cytokines (IL-4, IL-5, IL-10, and IL-13); transforming growth factor (TGF)-beta1, TGF-beta2, or TGF-beta3; and IL-1beta or TNF-alpha with or without IFN-gamma. Budesonide and exogenous prostaglandin (PG)E(2) were also evaluated. Postculture media were assayed for VEGF and PGE(2) by ELISA. RESULTS: IL-4, IL-5, and IL-13 alone but not IL-10 enhanced VEGF production by ASMC in a concentration-dependent manner. IFN-gamma alone inhibited spontaneous VEGF release by ASMC and concentration-dependently attenuated IL-4-augmented, IL-5-augmented, or IL-13-augmented production of VEGF (P <.01). All three TGF-beta isoforms augmented VEGF production, which was reduced by IFN-gamma (P <.005). IL-1beta also increased VEGF production, but this was not affected by IFN-gamma (P >.05). TNF-alpha alone had little effect on VEGF release by ASMC. Production of VEGF stimulated by all cytokines was inhibited by budesonide. Exogenous PGE(2) increased VEGF release, but cytokine modulation of PGE(2) release did not always correlate with VEGF release. CONCLUSIONS: T(H)2 cytokines and TGF-beta stimulate ASMC release of VEGF. This can be inhibited by IFN-gamma and glucocorticoids.     

Expression of transforming growth factor-beta and tumor necrosis factor-alpha in the plasma and tissues of mice with lupus nephritis

Although elevated levels of transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) have been implicated in renal disease, the tissue distribution and cellular localization of the induced cytokines is not well established. In this study, we investigated the expression of these cytokines during the progression of lupus nephritis in MRL lpr/lpr mice. The concentration of both cytokines increased in the plasma of these animals in an age-dependent manner, and there was an age-dependent induction of TGF-beta and TNF-alpha mRNAs in their kidneys. Although the increase in TGF-beta mRNA was specific for the kidney, the increase in TNF-alpha mRNA was widespread and also could be demonstrated in the liver, lung, and heart. In situ hybridization analysis of renal tissues from the lupus-prone mice localized TGF-beta mRNA to the glomerulus, and more specifically, to resident glomerular cells and inflammatory cells infiltrating periglomerular spaces in the nephritic lesions. The signals for TNF-alpha mRNA were detected only in inflammatory cells and were distributed throughout the nephritic kidney. Plasminogen activator inhibitor-1 (PAI-1) is known to be elevated in the glomeruli of MRL lpr/lpr mice, and intraperitoneal administration of either TGF-beta or TNF-alpha into normal mice markedly induced the expression of this potent inhibitor of fibrinolysis in renal glomerular or tubular cells in vivo. These results suggest that the increased renal expression of both cytokines may contribute to the development of lupus nephritis in this model and raise the possibility that PAI-1 may be involved. The fact that TGF-beta is specifically induced in the kidney whereas TNF-alpha increases in a variety of tissues, supports the hypothesis that the renal specificity of this disorder reflects the abnormal expression of TGF-beta.     

Coordinate cytokine gene expression in vivo following induction of tuberculous pleurisy in guinea pigs

Tuberculous pleurisy is a severe inflammatory response induced by Mycobacterium tuberculosis organisms that have escaped from lung granulomata into the pleural space during pulmonary infection. We have used the guinea pig model of tuberculous pleurisy to examine several aspects of the immune response to this antigen-specific inflammatory event. Pleurisy was induced by injection of heat-killed M. tuberculosis H37Rv directly into the pleural space of guinea pigs previously vaccinated with M. bovis BCG. Four animals were euthanized each day over a period of 9 days. Fluid in the pleural cavity was analyzed for transforming growth factor beta 1 (TGF-beta 1) and total interferon (IFN) protein levels. In addition, RNA was obtained from pleural cells and examined for TGF-beta 1, tumor necrosis factor alpha (TNF-alpha), IFN-gamma, and interleukin-8 (IL-8) expression by real-time PCR. Finally, pleural cells were examined for the ability to proliferate in response to concanavalin A and purified protein derivative (PPD) in vitro. In the pleural fluid, TGF-beta 1 protein concentrations increased over the course of the inflammatory response while IFN protein levels were not significantly altered. Expression of TGF-beta 1 mRNA peaked on days 3 and 4, and IFN-gamma mRNA expression peaked on day 3 and then returned to background levels. TNF-alpha mRNA expression was highest on days 2 to 4, and IL-8 mRNA levels remained elevated between days 2 and 5, peaking on day 3 before returning to background levels. PPD-induced proliferative responses were evident by day 3 and remained present throughout the study. Analysis of cytokine expression during tuberculous pleurisy may lead to a better understanding of the self-healing nature of this manifestation of tuberculosis.     

Hypophysectomy enhances interleukin-1beta, tumor necrosis factor-alpha, and interleukin-10 mRNA expression in the rat brain.

Although the effects of various cytokines as regulators of hormone synthesis and production are well documented, the role for pituitary hormones as modulators of cytokine synthesis is not fully understood. In this study, we investigated the effect of pituitary hormones' depletion on cytokine synthesis after short- (21 days) and long- (35 days) term hypophysectomy (ST-HX and LT-HX, respectively). The expresssion of the proinflammatory cytokine interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory cytokines IL-10 and transforming growth factor-beta (TGF-beta) in the rat brain was studied using in situ hybridization. Our results indicate that IL-1beta mRNA-expressing cells were significantly upregulated at day 21 in hypophysectomized rats compared to sham-operated controls. This enhanced expression was also detected later at day 35 post hypophysectomy. However, TNF-alpha mRNA expression was significantly increased only at the later sampling interval. IL-10 mRNA-expressing cells were increased after long-term hypophysectomy compared to controls. TGF-beta mRNA-expressing cells were not increased after hypophysectomy. In conclusion, these results suggest a role for pituitary hormones in IL-1beta, TNF-alpha, and IL-10 synthesis.     

In situ production of gamma interferon, interleukin-4, and tumor necrosis factor alpha mRNA in human lung tuberculous granulomas

Human tuberculous granulomas from five adults undergoing surgery for hemoptysis were analyzed by nonradioactive in situ hybridization for tumor necrosis factor alpha (TNF-alpha), gamma interferon (IFN-gamma), and interleukin-4 (IL-4) gene expression. All of the patients produced TNF-alpha mRNA. Three patients stained positive for both IFN-gamma and IL-4 mRNA; the other two stained positive for IFN-gamma but not IL-4 mRNA. Heterogeneity between the granulomas was observed in those patients staining positive for both IFN-gamma and IL-4 mRNA; these patients exhibited granulomas having IFN-gamma and not IL-4 mRNA as well as granulomas positive for both cytokine mRNAs. There was no evidence of caseation in these granulomas, and the cytokine patterns may represent events in the evolution of the granuloma. However, in those granulomas exhibiting caseous necrosis, very little IFN-gamma or IL-4 mRNA was observed, implying that progression of the granuloma is accompanied by a down regulation of T-cell responses. TNF-alpha mRNA expression was highest in patients with both IFN-gamma and IL-4 mRNA. Populations of CD68 positive macrophage-like cells within the granulomas produce mRNA for TNF-alpha, IFN-gamma, and IL-4. This implies that macrophages within the tuberculous granuloma may not be dependent on T-cell cytokines for modulation of their function but may be able to regulate their own activation state and that of the surrounding T cells. These findings have implications on the delivery of immunotherapies to patients with tuberculosis.     

Cerebrovascular transforming growth factor-beta contributes to inflammation in the Alzheimer's disease brain

Inflammatory mechanisms are thought to contribute to lesion pathogenesis and neuronal cell death in Alzheimer's disease. Transforming growth factor-beta (TGF-beta) plays a central role in the response of the brain to injury, and is increased in the brain in Alzheimer's disease. In this study we determine whether expression of TGF-beta is abnormal in the microvasculature in Alzheimer's disease and whether TGF-beta affects vascular production of pro-inflammatory cytokines, interleukin (IL)-1 beta, and tumor necrosis factor (TNF)-alpha. Microvessels isolated from the cortices of Alzheimer's disease patients and age-matched controls are analyzed for microvessel-associated and released TGF-beta. Results from Western blot analysis and enzyme-linked immunosorbent assay indicate a higher level of TGF-beta in Alzheimer's disease vessels compared to controls. To determine whether TGF-beta affects vascular release of inflammatory factors, cultured brain endothelial cells are treated with TGF-beta and levels of IL-1 beta and TNF-alpha determined. Both enzyme-linked immunosorbent assay and Western blot analyses show that untreated endothelial cells express little IL-1 beta or TNF-alpha, but incubation with TGF-beta results in robust expression of these factors by brain endothelial cells. Our results suggest that vessel-derived TGF-beta contributes to inflammatory processes in the Alzheimer brain.     

The Expression of Cytokine Genes in the Peritoneal Macrophages and Splenic CD4- and CD8-Positive Lymphocytes of the Nonobese Diabetic Mice

Type 1 diabetes is an autoimmune disease that results from the destruction of the insulin-producing pancreatic beta islet cells, probably via the influence of cytokines. However, direct correlation between the expression of selected cytokines by various immune cells at different time points during the progression of the disease has not yet been clearly demonstrated. In this study, we showed that the mRNA expression of the pro-inflammatory cytokines, TNF-alpha, IL-1 beta, IL-6, and GM-CSF, were increased while the anti-inflammatory cytokine, TGF-beta, decreased in the peritoneal macrophages of nonobese diabetic (NOD) mice. IL-6 expression however decreased when the mice became diabetic. Surprisingly the expression of IFN-gamma and IL-2 by splenic CD4+ cells were lower in 5-week-old NOD mice as compared to the nonobese diabetic resistant (NOR) control mice, but their expression was higher in older NOD mice. The expression of IL-4 and IL-10 decreased in splenic CD4-positive lymphocytes. Splenic CD8-positive lymphocytes expressed increased levels of IFN-gamma and IL-10 but the latter decreased sharply when diabetes occurred. The relevance of these findings to the pathogenesis of type 1 diabetes is discussed.     

Interleukin-6 and transforming growth factor-beta 1 control expression of cathepsins B and L in human lung epithelial cells.

Cathepsins B and L are commonly expressed cysteine proteinases that play a major role in lysosomal bulk proteolysis, protein processing, matrix degradation, and tissue remodeling. Cathepsins are also implicated in tumor progression and metastasis, tissue injury, and inflammation. Cells at sites of inflammation often show upregulation and secretion of cathepsins. The regulation of cathepsin expression by inflammatory mediators is not well understood. The aims of this study were to investigate the effect of the cytokines interleukin-1 beta (IL-1 beta), IL-6, IL-10, transforming growth factor-beta 1 (TGF-beta 1), and hepatocyte growth factor (HGF) on expression of cathepsin B and cathepsin L mRNA (quantitative RT-PCR), on protein expression (ELISA, Western blot), and also on enzymatic activity of cathepsins B and L. Investigations were performed using the human lung epithelial cell line A-549. IL-6 was found to induce a concentration-dependent increase in mRNA expression, protein concentration, and enzymatic activity of cathepsin L. Cathepsin B mRNA and protein expression were not affected by IL-6. In contrast, TGF-beta 1 decreased the amount of cathepsin L mRNA and cathepsin B mRNA. At protein level, it was shown that TGF-beta 1 clearly reduced the concentration of cathepsin L but not cathepsin B. The cytokines IL-1 beta, IL-10, and HGF were found to exert no effect on cathepsin B and L expression. In conclusion, these results are the first to show that IL-6 and TGF-beta 1 have opposite effects on the regulation of expression of cathepsins B and L in A-549 human lung epithelial cells. The proinflammatory cytokine IL-6 induced an upregulation of cathepsin L, whereas TGF-beta 1 suppressed cathepsin B and L expression. Further studies are needed to clarify the mechanism that affects cathepsin B and L expression.