Inflammatory mediators in chronic inflammatory bowel diseases

Crohn's disease and breast cancer: a literature review of the mechanisms and treatment

This is a literature review describes Crohn's disease (CD) concomitant with breast cancer and summarizes possible common pathogenic mechanisms shared by the two diseases involving the IL-17 and NF-κB signaling pathways. Inflammatory cytokines including TNF-α and Th17 cells in CD patients can induce activation of the ERK1/2, NF-κB and Bcl-2 pathways. Hub genes are involved in the generation of cancer stem cells (CSCs) and are related to inflammatory mediators, including CXCL8, IL1-β and PTGS2, which promote inflammation and breast cancer growth, metastasis, and development. CD activity is highly associated with altered intestinal microbiota processes, including secretion of complex glucose polysaccharides by Ruminococcus gnavus colonies; furthermore, γ-proteobacteria and Clostridium are associated with CD recurrence and active CD, while Ruminococcaceae, Faecococcus and Vibrio desulfuris are associated with CD remission. Intestinal microbiota disorder promotes breast cancer occurrence and development. Bacteroides fragilis can produce toxins that induce breast epithelial hyperplasia and breast cancer growth and metastasis. Gut microbiota regulation can also improve chemotherapy and immunotherapy efficacy in breast cancer treatment. Intestinal inflammation can affects the brain through the brain-gut axis, which activates the hypothalamic‒pituitary‒adrenal (HPA) axis to induce anxiety and depression in patients; these effects can inhibit the antitumor immune responses of the immune system and promote breast cancer occurrence in patients with CD. There are few studies on the treatment of patients with CD concomitant with breast cancer, but published studies show three main strategies: new biological agents combined with breast cancer treatment methods, intestinal fecal bacteria transplantation, and dietary treatment.

Acute Administration of Ojeok-san Ameliorates Pain-like Behaviors in Pre-Clinical Models of Inflammatory Bowel Diseases

(1) Background: Gastrointestinal pain and fatigue are the most reported concerns of patients with inflammatory bowel disease (IBD). Commonly prescribed drugs focus on decreasing excessive inflammation. However, up to 20% of IBD patients in an "inactive" state experience abdominal pain. The medicinal herb Ojeok-san (OJS) has shown promise in the amelioration of visceral pain. However, no research on OJS has been conducted in preclinical models of IBD. The mechanism by which OJS promotes analgesia is still elusive, and it is unclear if OJS possesses addictive properties. (2) Aims: In this study, we examined the potential of OJS to promote analgesic effects and rewarding behavior. Additionally, we investigated if tumor necrosis factor alpha (TNFα) from macrophages is a primary culprit of IBD-induced nociception. (3) Methods: Multiple animal models of IBD were used to determine if OJS can reduce visceral nociception. TNFα-macrophage deficient mice were used to investigate the mechanism of action by which OJS reduces nociceptive behavior. Mechanical sensitivity and operant conditioning tests were used to determine the analgesic and rewarding effects of OJS. Body weight, colon length/weight, blood in stool, colonic inflammation, and complete blood count were assessed to determine disease progression. (4) Results: OJS reduced the evoked mechanical nociception in the dextran sulphate sodium model of colitis and IL-10 knockout (KO) mice and delayed aversion to colorectal distension in C57BL/6 mice. No rewarding behavior was observed in OJS-treated IL-10 KO and mdr1a KO mice. The analgesic effects of OJS are independent of macrophage TNFα levels and IBD progression. (5) Conclusions: OJS ameliorated elicited mechanical and visceral nociception without producing rewarding effects. The analgesic effects of OJS are not mediated by macrophage TNFα.

Pharmacological activities of the organic extracts and fatty acid composition of the petroleum ether extract from Haplophyllum tuberculatum leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Haplophyllum tuberculatum is used in traditional medicine to treat many disorders including inflammation and pain. The aim of this study is to investigate the organic extracts from H. tuberculatum leaves against inflammation, gastric ulcer and pain.

MATERIALS AND METHODS

Acute toxicity was studied in vivo to determine the toxic doses of the organic extracts. Anti-inflammatory activity was also evaluated in vivo using carrageenan-induced paw edema in Wistar rats. Gastroprotective activity was tested using the HCl/ethanol-induced gastric ulcer test in rats. Peripheral and central analgesic activities were assessed using the acetic acid-induced writhing test and the hot-plate method, respectively. The chemical composition of the fatty acids in the petroleum ether (PE) extract was determined with GC-MS.

RESULTS

At 25, 50 and 100mg/kg PE extract was the most active against inflammation. Percentages inhibition 5h after carrageenan-injection were 51.12; 86.71% and 96.92%, respectively. The same extract at 100mg/kg showed good analgesic activities using the acetic acid-induced writhing test and the hot-plate method. The chloroform, ethyl acetate (EtOAc) and butanolic (n-BuOH) extracts exhibited strong anti-inflammatory, gastroprotective and analgesic activities at 100mg/kg. The GC-FID analysis revealed that the PE extract was rich in γ-linolenic acid (45.50%) followed by palmitic acid (18.48%), linoleic acid (10.73%), erucic acid (4.72), stearic acid (3.96%) and oleic acid (2.57%).

CONCLUSION

The results of the present study support the traditional use of the leaves of H. tuberculatum and may possibly serve as prospective material for further development of safe new phytochemical anti-inflammatory, gastroprotective and/or analgesic agents.

Coagulation and inflammation. Molecular insights and diagnostic implications

Overwhelming evidence has linked inflammatory disorders to a hypercoagulable state. In fact, thromboembolic complications are among the leading causes of disability and death in many acute and chronic inflammatory diseases. Despite this clinical knowledge, coagulation and immunity were long regarded as separate entities. Recent studies have unveiled molecular underpinnings of the intimate interconnection between both systems. The studies have clearly shown that distinct pro-inflammatory stimuli also activate the clotting cascade and that coagulation in turn modulates inflammatory signaling pathways. In this review, we use evidence from sepsis and inflammatory bowel diseases as a paradigm for acute and chronic inflammatory states in general and rise hypotheses how a systematic molecular understanding of the "inflammation-coagulation" crosstalk may result in novel diagnostic and therapeutic strategies that target the inflammation-induced hypercoagulable state.

Cellular pathology of experimental colitis induced by trinitrobenzenesulphonic acid (TNBS): protective effects of recombinant human interleukin-11

The objective of this study was to elucidate colonic mucosal ultrastructural effects of trinitrobenzene-sulphonic acid (TNBS) with and without co-administration of recombinant human interleukin-11 (rhIL-11). Using a standard colitis model (ir alcoholic TNBS), rats were sacrificed at 3~14 days after TNBS. Co-administration of rhIL-11 (100, 300 or 1000 mug/kg sc) was given for protection, and controls received saline or alcohol ir, or rhIL-11 sc alone. Transmission electron microscopy revealed that early TNBS-induced cytopathology was primarily in absorptive cells, changes which occurred prior to goblet cell damage. Progressive cellular changes included vacuolization and increased multivesicular bodies in cell apices, disconfiguration of microvilli, enlarged Golgi apparatuses, enlargement of basal inter-cellular spaces, and eventual desquamation of epithelium and apical bursting.Organelle damage preceded surface changes and resembled ultrastructural changes reported for human ulcerative colitis. The principal effect of rhIL-11 was apparent massive release of mucus from goblet cells, filling the colonic crypts, and suggesting a mode of its protection.

Th17 cells in human disease

SUMMARY

Our understanding of the role of T cells in human disease is undergoing revision as a result of the discovery of T-helper 17 (Th17) cells, a unique CD4(+) T-cell subset characterized by production of interleukin-17 (IL-17). IL-17 is a highly inflammatory cytokine with robust effects on stromal cells in many tissues. Recent data in humans and mice suggest that Th17 cells play an important role in the pathogenesis of a diverse group of immune-mediated diseases, including psoriasis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, and asthma. Initial reports also propose a role for Th17 cells in tumorigenesis and transplant rejection. Important differences, as well as many similarities, are emerging when the biology of Th17 cells in the mouse is compared with corresponding phenomena in humans. As our understanding of human Th17 biology grows, the mechanisms underlying many diseases are becoming more apparent, resulting in a new appreciation for both previously known and more recently discovered cytokines, chemokines, and feedback mechanisms. Given the strong association between excessive Th17 activity and human disease, new therapeutic approaches targeting Th17 cells are highly promising, but the potential safety of such treatments may be limited by the role of these cells in normal host defenses against infection.

Th17 cells in human disease

SUMMARY

Our understanding of the role of T cells in human disease is undergoing revision as a result of the discovery of T-helper 17 (Th17) cells, a unique CD4(+) T-cell subset characterized by production of interleukin-17 (IL-17). IL-17 is a highly inflammatory cytokine with robust effects on stromal cells in many tissues. Recent data in humans and mice suggest that Th17 cells play an important role in the pathogenesis of a diverse group of immune-mediated diseases, including psoriasis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, and asthma. Initial reports also propose a role for Th17 cells in tumorigenesis and transplant rejection. Important differences, as well as many similarities, are emerging when the biology of Th17 cells in the mouse is compared with corresponding phenomena in humans. As our understanding of human Th17 biology grows, the mechanisms underlying many diseases are becoming more apparent, resulting in a new appreciation for both previously known and more recently discovered cytokines, chemokines, and feedback mechanisms. Given the strong association between excessive Th17 activity and human disease, new therapeutic approaches targeting Th17 cells are highly promising, but the potential safety of such treatments may be limited by the role of these cells in normal host defenses against infection.

IL1beta- and LPS-induced serotonin secretion is increased in EC cells derived from Crohn's disease

Gut mucosal enterochromaffin (EC) cells are regarded as key regulators of intestinal motility and fluid secretion via secretion of serotonin (5HT), are increased in numbers in mucosal inflammation and located in close proximity to immune cells. We examined whether interleukin (IL)1beta and Escherichia coli lipopolysaccharide (LPS) induced EC cell 5HT release through Toll-like/IL-1 (TIL) receptor activation, nuclear factor kappa B (NFkappaB) and mitogen-activated protein kinase (MAPK) phosphorylation and evaluated whether somatostatin could inhibit this phenomenon. Pure (>98%) human intestinal EC cells were isolated by fluorescent activated cell sorting from preparations of normal (n = 5) and Crohn's colitis (n = 6) mucosa. 5HT release was measured (ELISA), and NFkappaB and ERK phosphorylation quantitated (ELISA) in response to IL1beta and LPS. 5HT secretion was increased by both E. coli LPS (EC(50) = 5 ng mL(-1)) and IL1beta (EC(50) = 0.05 pmol L(-1)) >2-fold (P < 0.05) in Crohn's EC cells compared with normal EC cells. Secretion was reversible by the TLR4 antagonist, E. coli K12 LPS (IC(50) = 12 ng mL(-1)) and the IL1beta receptor antagonist (ILRA; IC(50) = 3.4 ng mL(-1)). IL1beta caused significant (P < 0.05) NFkappaB and MAPK phosphorylation (40-55%). The somatostatin analogue, lanreotide inhibited IL1beta-stimulated secretion in Crohn's (IC(50) = 0.61 nmol L(-1)) and normal EC cells (IC(50) = 1.8 nmol L(-1)). Interleukins (IL1beta) and bacterial products (E. coli LPS) stimulated 5HT secretion from Crohn's EC cells via TIL receptor activation (TLR4 and IL1beta). Immune-mediated alterations in EC cell secretion of 5HT may represent a component of the pathogenesis of abnormal bowel function in Crohn's disease. Inhibition of EC cell-mediated 5HT secretion may be an alternative therapeutic strategy in the amelioration of inflammatory bowel disease symptomatology.

Regulation of the eicosanoid pathway by tumour necrosis factor alpha and leukotriene D4 in intestinal epithelial cells

In this study the mRNA and protein levels of the key enzymes involved in eicosanoid biosynthesis and the cysteinyl leukotriene receptors (CysLT1R and CysLT2R) have been analysed in non-transformed intestinal epithelial and colon cancer cell lines. Our results revealed that tumour necrosis factor alpha (TNF-alpha), and leukotriene D4 (LTD4), which are inflammatory mediators implicated in carcinogenesis, stimulated an increase of cyclooxygenase-2 (COX-2), in non-transformed epithelial cells, and 5-lipoxygenase (5-LO) in both non-transformed and cancer cell lines. Furthermore, these mediators also stimulated an up-regulation of LTC4 synthase in cancer cells as well as non-transformed cells. We also observed an endogenous production of CysLTs in these cells. TNF-alpha and LTD4, to a lesser extent, up-regulate the CysLT1R levels. Interestingly, TNF-alpha also reduced CysLT2R expression in cancer cells. Our results demonstrate that inflammatory mediators can cause intestinal epithelial cells to up-regulate the expression of enzymes needed for the biosynthesis of eicosanoids, including the cysteinyl leukotrienes, as well as the signal transducing proteins, the CysLT receptors, thus providing important mechanisms for both maintaining inflammation and for tumour progression.

Glutamine supplementation increases Th1-cytokine responses in murine intestinal intraepithelial lymphocytes

Intestinal intraepithelial lymphocytes (IELs) are major effector cells in the gut mucosal immune system, and are phenotypically distinct from thymic and peripheral T cells. Although nutritional supplementation with glutamine affects the intestinal immune response, it remains unclear whether this is a direct effect via the IEL-derived cytokines. This study examined changes in IEL-derived cytokine production following treatment with glutamine in vitro. Murine IELs were purified and activated with PMA plus ionomycin, and then cultured in the presence of various glutamine concentrations. IEL-derived cytokines were measured using a cytometric bead array (CBA) system, and IEL subsets were analyzed by flow cytometry. Treatment with glutamine increased the production of IL-2 and IFN-gamma from IELs in the presence of PMA plus ionomycin, but had no effect on TNFalpha, IL-4, or IL-5 production. Treatment with alanine or glucose had no regulatory effect on IEL-derived cytokines. Glutamine therefore had a direct effect on the production of selected IEL-derived Th1-cytokines, and enteral supplementation with glutamine may influence the intestinal immune responses mediated by IELs.

On the action of methotrexate and 6-mercaptopurine on M. avium subspecies paratuberculosis

Background

Clinical improvement in inflammatory bowel disease (IBD) treated with methotrexate and 6-mercaptopurine (6-MP) is associated with a decrease in pro-inflammatory cytokines. This has been presumed to indicate the mechanism of action of methotrexate and 6-MP. Although controversial, there are increasingly compelling data that Mycobacterium avium subspecies paratuberculosis (MAP) may be an etiological agent in some or all of IBD. We hypothesized that the clinical efficacy of methotrexate and 6-MP in IBD may be to simply inhibit the growth of MAP.

Methodology

The effect on MAP growth kinetics by methotrexate and 6-MP were evaluated in cell culture of two strains each of MAP and M. avium using a radiometric (¹⁴CO₂ BACTEC®) detection system that quantifies mycobacterial growth as arbitrary “growth index units” (GI). Efficacy data are presented as “percent decrease in cumulative GI” (% −ΔcGI).

Principal Findings

The positive control antibiotic (clarithromycin) has ≥85% −ΔcGI at a concentration of 0.5 µg/ml. The negative control (ampicillin) has minimal inhibition at 64 µg/ml. MAP ATCC 19698 shows ≥80% −ΔcGI for both agents by 4 µg/ml. With the other three isolates, although more effective than ampicillin, 6-MP is consistently less effective than methotrexate.

Conclusions

We show that methotrexate and 6-MP inhibit MAP growth in vitro. Each of the four isolates manifests different % −ΔcGI. These data are compatible with the hypothesis that the clinical improvement in patients with IBD treated with methotrexate and 6-MP could be due to treating a MAP infection. The decrease in pro-inflammatory cytokines, thought to be the primary mechanism of action, may simply be a normal, secondary, physiological response. We conclude that henceforth, in clinical studies that evaluate the effect of anti-MAP agents in IBD, the use of methotrexate and 6-MP should be excluded from any control groups.

Transforming growth factor beta enhances respiratory syncytial virus replication and tumor necrosis factor alpha induction in human epithelial cells

Asthma is characterized as a chronic inflammatory disease associated with significant tissue remodeling. Patients with asthma are more susceptible to virus-induced exacerbation, which subsequently can lead to increased rates of hospitalization and mortality. While the most common cause of asthma-related deaths is respiratory viral infections, the underlying factors in the lung environment which render asthmatic subjects more susceptible to viral exacerbation are not yet identified. Since transforming growth factor beta (TGF-beta) is a critical cytokine for lung tissue remodeling and asthma phenotype, we have focused on the effects of TGF-beta on viral replication and virus-induced inflammation. Treatment of human epithelial cells with TGF-beta increased respiratory syncytial virus (RSV) replication by approximately fourfold. Tumor necrosis factor alpha (TNF-alpha) mRNA and protein expression were also significantly increased above levels with RSV infection alone. The increase in RSV replication and TNF-alpha expression after TGF-beta treatment was concomitant with an increase in virus-induced p38 mitogen-activated protein kinase activation. Our data reveal a novel effect for TGF-beta on RSV replication and provide a potential mechanism for the exaggerated inflammatory response observed in asthmatic subjects during respiratory viral infections.

c-Fos is a critical mediator of inflammatory-mediated repression of the apical sodium-dependent bile acid transporter

BACKGROUND & AIMS

Ileal bile acid malabsorption is present in Crohn's ileitis. The molecular mechanisms of regulation of the apical sodium-dependent bile acid transporter (ASBT) by inflammatory cytokines in vitro and in vivo are investigated.

METHODS

Transient transfection studies of the human, mouse, and rat ASBT promoters and Northern analyses were performed in cells treated with the inflammatory cytokines and/or various activator protein-1 constructs. Rat ASBT promoter transgenic, wild-type, and c-fos-null mice were treated with indomethacin to assess the response to acute inflammation of the ileal mucosa.

RESULTS

In Caco-2 cells, ASBT messenger RNA expression was reduced 65% after interleukin-1beta treatment, while c-fos and c-jun were up-regulated 2-fold. Human ASBT promoter activity was enhanced by c-jun and repressed by a dominant negative c-jun, c-fos, or a dominant negative c-fos. Meanwhile, c-fos antisense treatment activated the human ASBT promoter 5-fold and not only abrogated interleukin-1beta-mediated repression but led to a paradoxical increase in ASBT promoter activity. Indomethacin-induced acute ileitis led to repression of ASBT in wild-type mice and in the transgenic rat ASBT promoter reporter, while paradoxical activation of ASBT was seen in c-fos-null mice. Indomethacin-induced ileal injury was greater in the c-fos-null mice compared with the wild-type littermates.

CONCLUSIONS

Human, rat, and mouse ASBT is inhibited by inflammatory cytokines via direct interactions of c-fos with the ASBT promoter.

Folate Receptor-Mediated Drug Targeting: From Therapeutics to Diagnostics

Folate targeted drug delivery has emerged as an alternative therapy for the treatment and imaging of many cancers and inflammatory diseases. Due to its small molecular size and high binding affinity for cell surface folate receptors (FR), folate conjugates have the ability to deliver a variety of molecular complexes to pathologic cells without causing harm to normal tissues. Complexes that have been successfully delivered to FR expressing cells, to date, include protein toxins, immune stimulants, chemotherapeutic agents, liposomes, nanoparticles, and imaging agents. This review will summarize the applications of folic acid as a targeting ligand and highlight the various methods being developed for delivery of therapeutic and imaging agents to FR-expressing cells.

The insulin-like growth factor system and markers of inflammation in adult patients with inflammatory bowel disease

BACKGROUND AND OBJECTIVES

Catabolism and growth impairment are well-known complications of inflammatory bowel disease (IBD). Recent studies have demonstrated significant changes in the IGF system in IBD patients. The aim of the present study was to investigate correlations between the IGF system and markers of inflammation in IBD.

METHODS

A cross-sectional study comprising 99 IBD patients (Crohn's disease (CD, n = 50) and ulcerative colitis (UC, n = 49)). Correlations between markers of inflammation and IGF-I, IGF-II and IGFBP-3 were examined in CD and UC patients in remission and relapse. The patients were clinically scored using Crohn's Disease Activity Index (CDAI) for CD patients and Activity Index (AI) for UC patients.

RESULTS

In the UC group we found correlations between IGF-I and CRP (r(s) = Spearman's rho) (r(s) = -0.40, p < 0.01) and albumin (r(s) = 0.46, p < 0.001), IGFBP-3 and albumin (r(s) = 0.36, p < 0.01) and AI score (r(s) = -0.31, p < 0.05). IGF-II correlated with CRP (r(s) = -0.42, p < 0.01), IL-6 (r(s) = -0.65, p < 0.001), albumin (r(s) = 0.41, p < 0.01), AI score (r(s) = -0.30, p < 0.05) and orosomucoid (r(s) = -0.47, p < 0.001). In the CD group we found correlations between IGF-I and CRP (r(s) = -0.40, p < 0.05), and albumin (r(s) = -0.46, p < 0.01), IGFBP-3 and albumin (r = 0.36, p < 0.01). IGF-II correlated with IL-6 (r(s) = -0.65, p < 0.001), albumin (r(s) = 0.41, p < 0.01), CDAI score (r(s) = -0.30, p < 0.05) and orosomucoid (r(s) = -0.47, p < 0.001).

CONCLUSIONS

IGF-I, IGF-II and IGFBP-3 are correlated to albumin and IGF-I and IGF-II are correlated to CRP in IBD patients. Further, IGF-II is correlated to IL-6 in IBD patients. This may suggest a correlation between inflammation and the IGF system with involvement in muscle and bone catabolism in IBD.

Inflammatory-mediated repression of the rat ileal sodium-dependent bile acid transporter by c-fos nuclear translocation

BACKGROUND & AIMS

Ileal malabsorption of bile salts is observed in Crohn's ileitis. We define the transcriptional mechanisms involved in cytokine-mediated repression of the rat apical sodium-dependent bile acid transporter (ASBT).

METHODS

ASBT regulation was studied in IL-1beta-treated IEC-6 and Caco-2 cells and in indomethacin-treated rats.

RESULTS

Indomethacin-induced ileitis in Lewis rats leads to specific reductions in ileal ASBT messenger RNA and protein levels, whereas c-jun and c-fos are induced. The proinflammatory cytokines interleukin-1beta and tumor necrosis factor repress the activity of the ASBT promoter in Caco-2 and intestinal epithelial cell-6 cells. This effect is blocked by the proteasome inhibitor, MG-132, or by the phosphatidyl inositol 3-kinase inhibitor, wortmannin. Indomethacin (in vivo) or proinflammatory cytokine (in vitro) treatment leads to serine phosphorylation and nuclear translocation of c-fos. Mutation of a 5' activated protein (AP)-1 site inactivates the ASBT promoter, whereas mutation of the 3' site abrogates the proinflammatory cytokine-mediated repression. The 5' site binds a c-jun homodimer, whereas the 3' site binds a c-jun/c-fos heterodimer. c-Jun overexpression enhances ASBT promoter activity, whereas a dominant negative c-jun construct inactivates the promoter. c-Fos overexpression represses promoter activity. A 27 base pair cis-element from the 3' site in the ASBT promoter imparts cytokine-mediated down-regulation to a heterologous SV40 promoter construct.

CONCLUSIONS

The ASBT promoter contains 2 distinct cis AP-1 elements; the 5' element binds homodimeric c-jun and mediates basal transcription. Inflammation is associated with up-regulation, phosphorylation, and nuclear translocation of c-fos, which then represses ASBT promoter activity via binding of the 3' AP-1 element by a c-fos/c-jun heterodimer.

The Regulation and Functional Consequence of Proinflammatory Cytokine Binding on Human Intestinal Epithelial Cells

Products of an activated immune system may affect cells within the immune system as well as nonlymphoid cells in the local environment. Given the immunologically activated state of the intestinal tract, it is conceivable that locally produced cytokines could regulate epithelial cell function. To assess whether epithelial cells are targets for particular cytokines, we initiated studies on the binding of a panel of proinflammatory cytokines in freshly isolated epithelial cells from normal and inflammatory bowel disease (IBD) patients as well as in cell lines. Isolated intestinal epithelial cells (IEC) were stained with phycoerythrin-conjugated or biotinylated cytokines to determine the expression and density of receptors for IL-1β, IL-6, granulocyte-macrophage CSF (GM-CSF), and TNF-α. Receptors for IL-1β, IL-6, and GM-CSF were readily detectable in all epithelial cell preparations at levels equal to (GM-CSFR) or lower than those seen on monocytes. However TNFα-R were not detectable on freshly isolated IECs. Receptor density was greater in surface vs crypt epithelial cells, but no significant differences were seen between normal and IBD epithelial cells. Expression of IL-1R and IL-6R was enhanced by LPS and IFN-γ. Functionally, IL-1β enhanced proliferation of the IEC cell line, DLD1, whereas GM-CSF treatment of de-differentiated crypt-like DLD1 and HT29 cells resulted in enhanced expression of ICAM-1. Furthermore, TNF-α treatment enhanced the secretion of IL-8 and GRO-α in HT29 cells, but not in freshly isolated IEC cultures. The differential binding and function of proinflammatory cytokines on IEC support the hypothesis that these cytokines may be involved in normal physiological processes as well as in regulating mucosal immune responses.

Hyperthermia decreases cytokine-mediated adhesion molecule expression on human umbilical vein endothelial cells

Although hyperthermia has been used as an effective cancer treatment modality, its effects on metastasis of tumour cells are not clear. Since adhesion molecules play a key role in metastasis, we evaluated how the expression of adhesion molecules is influenced by hyperthermia. Human umbilical vein endothelial cells were incubated in vitro for 1 h. at 39, 42, 43 and 44 degrees C with and without addition of tumour-necrosis factor (TNF) or interferon-gamma (IFN-gamma) and the expression of endothelial cell leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule-1 (ICAM-1) and major histocompatibility complex (MHC) class-II molecule was measured. Expression of MHC class-II molecules and expression of unstimulated constituent ICAM-1's was not reduced by heat treatment. In contrast, expression of cytokine-induced ELAM-1's and ICAM-1's was significantly lower after heat treatment. The adhesion to HUVEC in vitro of HL-60 leukemia cells, which express sialyl-Lewis-x antigen as a ligand to ELAM-1, was diminished after incubation at 42 degrees C and totally lost after treatment at 44 degrees C. This suggests that any decrease in metastasis formation after heat treatment, which is occasionally observed, could be due to a reduced action of TNF or related cytokines on adhesion molecule induction and subsequent membrane expression by the endothelial cell. A possible underlying mechanism involved is a heat-induced alteration or blockage of the biosynthetic pathways required for synthesis of ELAM-1 and ICAM-1 proteins.

Elevation of interleukin-6 in inflammatory bowel disease is macrophage- and epithelial cell-dependent

Local interleukin-6 (IL-6) activity was studied using colonic mucosal tissues in inflammatory bowel disease (IBD) and inflammatory control patients. Active IBD specimens exhibited significantly higher IL-6 activity than control specimens in both cultures of isolated lamina propria mononuclear cells (LPMC) and mucosal tissues with an increased number of IL-6-producing cells. However, the activity in inactive IBD or inflammatory controls did not differ from controls. Northern blot analysis demonstrated IL-6 messenger RNA in LPMC and colonic epithelial cells isolated from active IBD specimens but not in control cells. Furthermore, immunofluorescent microscopic study of active IBD specimens showed more conspicuous staining of IL-6 in infiltrating LPMC (mostly CD68+ cells) and colonic epithelial cells. These results suggest that elevation of local IL-6 activity may be a characteristic feature of active IBD and both macrophages and colonic epithelial cells are the major cell types responsible for this phenomenon.

Tumor necrosis factor-alpha potentiates phospholipase A2-stimulated release and metabolism of arachidonic acid in cultured intestinal epithelial cells (INT 407)

Tumor necrosis factor-alpha (TNF-alpha), a known pro-inflammatory cytokine, has been suggested to play a role in the pathogenesis of inflammatory bowel disease (IBD) by mediating damage to the intestinal epithelial cells. The present study demonstrates that TNF-alpha potentiates release and metabolism of 14C-labeled arachidonic acid (14C-AA) in cultured intestinal epithelial cells (INT 407). Although TNF-alpha on its own was but a weak stimulator of cellular 14C-AA turnover, it significantly potentiated the release of 14C-AA and 14C-labeled prostaglandin E2(14C-PGE2) after stimulation with three known phospholipase A2 activators: phospholipase. C from Clostridium perfringens, the calcium ionophore A23187, and the phorbol ester 4-beta-phorbol-12-myristate-13-acetate (PMA). The phospholipase A2 inhibitor quinacrine significantly reduced both AA and PGE2 release after combined stimulation with phospholipase C and TNF-alpha. In contrast to its effect on the AA turnover, TNF-alpha did not affect the phospholipase C-stimulated production of platelet-activating factor (PAF-acether). Taken together, these findings indicate that a) TNF-alpha potentiates phospholipase A2-stimulated AA release from cultured intestinal epithelial cells; b) TNF-alpha may stimulate phospholipase A2-dependent AA release without affecting the formation of PAF-acether and c) pretreatment with TNF-alpha potentiates the formation of PGE2 after stimulation with phospholipase A2 activators. In summary, the present investigation points to the possibility that TNF-alpha may stimulate intestinal epithelial cells to produce biologically active AA metabolites and that this stimulation may be modulated by components of the intestinal luminal content, like bacterial toxins.