Chlamydial and human heat shock protein 60s activate human vascular endothelium, smooth muscle cells, and macrophages. (1/14219)

Both chlamydial and human heat shock protein 60s (HSP 60), which colocalize in human atheroma, may contribute to inflammation during atherogenesis. We tested the hypothesis that chlamydial or human HSP 60 activates human endothelial cells (ECs), smooth muscle cells (SMCs), and monocyte-derived macrophages. We examined the expression of adhesion molecules such as endothelial-leukocyte adhesion molecule-1 (E-selectin), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1), and the production of the proinflammatory cytokine interleukin-6 (IL-6). We also tested whether either HSP 60 induces nuclear factor-kappaB (NF-kappaB), which contributes to the gene expression of these molecules. Either chlamydial or human HSP 60 induced E-selectin, ICAM-1, and VCAM-1 expression on ECs similar to levels induced by Escherichia coli lipopolysaccharide (LPS). Each HSP 60 also significantly induced IL-6 production by ECs, SMCs, and macrophages to an extent similar to that induced by E. coli LPS, as assessed by enzyme-linked immunosorbent assay (ELISA). In ECs, either HSP 60 triggered activation of NF-kappaB complexes containing p65 and p50 Rel proteins. Heat treatment abolished all these effects, but did not alter the ability of E. coli LPS to induce these functions. Chlamydial and human HSP 60s therefore activate human vascular cell functions relevant to atherogenesis and lesional complications. These findings help to elucidate the mechanisms by which a chronic asymptomatic chlamydial infection might contribute to the pathophysiology of atheroma.  (+info)

Interleukin-6 dependent induction of the cyclin dependent kinase inhibitor p21WAF1/CIP1 is lost during progression of human malignant melanoma. (2/14219)

Human melanoma cell lines derived from early stage primary tumors are particularly sensitive to growth arrest induced by interleukin-6 (IL-6). This response is lost in cell lines derived from advanced lesions, a phenomenon which may contribute to tumor aggressiveness. We sought to determine whether resistance to growth inhibition by IL-6 can be explained by oncogenic alterations in cell cycle regulators or relevant components of intracellular signaling. Our results show that IL-6 treatment of early stage melanoma cell lines caused G1 arrest, which could not be explained by changes in levels of G1 cyclins (D1, E), cdks (cdk4, cdk2) or by loss of cyclin/cdk complex formation. Instead, IL-6 caused a marked induction of the cdk inhibitor p21WAF1/CIP1 in three different IL-6 sensitive cell lines, two of which also showed a marked accumulation of the cdk inhibitor p27Kip1. In contrast, IL-6 failed to induce p21WAF1/CIP1 transcript and did not increase p21WAF1/CIP1 or p27kip1 proteins in any of the resistant lines. In fact, of five IL-6 resistant cell lines, only two expressed detectable levels of p21WAF1/CIP1 mRNA and protein, while in three other lines, p21WAF1/CIP1 was undetectable. IL-6 dependent upregulation of p21WAF1/CIP1 was associated with binding of both STAT3 and STAT1 to the p21WAF1/CIP1 promoter. Surprisingly, however, IL-6 stimulated STAT binding to this promoter in both sensitive and resistant cell lines (with one exception), suggesting that gross deregulation of this event is not the unifying cause of the defect in p21WAF1/CIP1 induction in IL-6 resistant cells. In somatic cell hybrids of IL-6 sensitive and resistant cell lines, the resistant phenotype was dominant and IL-6 failed to induce p21WAF1/CIP1. Thus, our results suggest that in early stage human melanoma cells, IL-6 induced growth inhibition involves induction of p21WAF1/CIP1 which is lost in the course of tumor progression presumably as a result of a dominant oncogenic event.  (+info)

Effects of soybean oil emulsion and eicosapentaenoic acid on stress response and immune function after a severely stressful operation. (3/14219)

OBJECTIVE: To investigate the effects of soybean oil emulsion and oral or enteral administration of eicosapentaenoic acid (EPA) on stress response, cytokine production, protein metabolism, and immune function after surgery for esophageal cancer. SUMMARY BACKGROUND DATA: It has been reported that safflower oil, rich in n-6 polyunsaturated fatty acid (n-6 PUFA), affects the survival rate of septic animals and decreases the immune function. It has also been reported that the administration of fish oil, in contrast, reduces these stress responses and stress-induced immunosuppression. In humans, the effects of soybean oil emulsion and the administration of EPA on stress response and immune function after surgery have not been established. METHODS: Patients who underwent esophagectomy with thoracotomy were divided into three groups. Seven patients were fed by total parenteral nutrition (TPN) with soybean oil emulsion, which accounted for 20% of total calories. Seven patients were given oral or enteral administration of 1.8 g/day EPA, in addition to TPN with soybean oil emulsion. Nine patients served as the control group; these patients received fat-free TPN. Serum interleukin-6 (IL-6), C-reactive protein, concanavalin A (con A)- or phytohemagglutinin (PHA)-stimulated lymphocyte proliferation, natural killer cell activity, and stress hormones were measured. RESULTS: The postoperative level of serum IL-6 was significantly higher in the group receiving soybean oil emulsion than in the fat-free group. Oral or enteral supplementation of EPA with soybean oil emulsion significantly reduced the level of serum IL-6 compared with the patients receiving soybean oil emulsion. Con A- or PHA-stimulated lymphocyte proliferation decreased significantly on postoperative day 7 in all groups of patients. The supplementation of EPA with soybean oil emulsion significantly improved the lymphocyte proliferation and natural killer cell activity on postoperative day 21 compared with the group receiving soybean oil emulsion. CONCLUSIONS: Soybean oil emulsion amplifies, and the supplementation of EPA reduces, the stress response and stress-induced immunosuppression.  (+info)

Alpha-toxin and gamma-toxin jointly promote Staphylococcus aureus virulence in murine septic arthritis. (4/14219)

Septic arthritis is a common and feared complication of staphylococcal infections. Staphylococcus aureus produces a number of potential virulence factors including certain adhesins and enterotoxins. In this study we have assessed the roles of cytolytic toxins in the development of septic arthritis by inoculating mice with S. aureus wild-type strain 8325-4 or isogenic mutants differing in the expression of alpha-, beta-, and gamma-toxin production patterns. Mice inoculated with either an alpha- or beta-toxin mutant showed degrees of inflammation, joint damage, and weight decrease similar to wild-type-inoculated mice. In contrast, mice inoculated with either double (alpha- and gamma-toxin-deficient)- or triple (alpha-, beta-, and gamma-toxin-deficient)-mutant S. aureus strains showed lower frequency and severity of arthritis, measured both clinically and histologically, than mice inoculated with the wild-type strain. We conclude that simultaneous production of alpha- and gamma-toxin is a virulence factor in S. aureus arthritis.  (+info)

Effects of lipopolysaccharide on production of interleukin-1 and interleukin-6 by bovine mammary epithelial cells in vitro. (5/14219)

This investigation was performed to determine the effect of lipopolysaccharide (LPS) on production of interleukin (IL)-1 and IL-6 by bovine mammary epithelial cells in vitro. After confluence, the cells were stimulated with LPS (0.1, 1.0 or 10 micrograms/ml) for 4, 8, 24, and 48 hr. LPS increased production of both IL-1 and IL-6 production from mammary cells in a dose dependent manner. The expression of mRNA for IL-1 receptor antagonist (IL-1ra) was demonstrated by reverse transcription-polymerase chain reaction in bovine mammary epithelial cells.  (+info)

Medroxyprogesterone acetate inhibits interleukin 6 secretion from KPL-4 human breast cancer cells both in vitro and in vivo: a possible mechanism of the anticachectic effect. (6/14219)

Interleukin 6 (IL-6) is a multifunctional cytokine. Recent reports suggest that circulating IL-6 secreted from tumour cells plays an important role in cancer-induced cachexia. Medroxyprogesterone acetate (MPA) has been used as an endocrine therapeutic agent for patients with breast cancer. It has been suggested that MPA decreases serum IL-6 levels and preserves the bodyweight of patients with advanced breast cancer. However, the mechanisms of action responsible for the anticachectic effect of MPA have not been elucidated. Therefore, the effects of MPA on IL-6 secretion were studied both in vitro and in vivo using a human breast cancer cell line, KPL-4, which secretes IL-6 into medium and induces cachexia when injected into female nude mice. MPA (10-1000 nM) dose-dependently decreased basal IL-6 secretion into medium, and also suppressed tumour necrosis factor (TNF-alpha)-induced IL-6 secretion. Both basal and TNF-alpha-induced IL-6 mRNA levels were dose-dependently lowered by MPA. Moreover, intramuscular injections of MPA (100 mg kg(-1) twice a week) into nude mice bearing KPL-4 transplanted tumours significantly decreased serum IL-6 levels without affecting tumour growth and preserved the bodyweight of recipient mice. These findings suggest that suppression of IL-6 secretion from tumour cells, at least in part, causes the anticachectic effect of MPA.  (+info)

C5a receptor and interleukin-6 are expressed in tissue macrophages and stimulated keratinocytes but not in pulmonary and intestinal epithelial cells. (7/14219)

The anaphylatoxin derived from the fifth component of the human complement system (C5a) mediates its effects by binding to a single high-affinity receptor (C5aR/CD88), the expression of which has been traditionally thought to be restricted to granulocytes, monocytes, macrophages (Mphi), and cell lines of myeloid origin. Recent immunohistochemical data suggested that human bronchial and alveolar cells express C5aR as well. To reexamine the tissue distribution of human C5aR expression, transcription of the C5aR gene was investigated in normal and pathologically affected human lung (bronchopneumonia, tuberculosis), large intestine (acute appendicitis, Crohn's disease), and skin (pyogenic granuloma, lichen planus) using in situ hybridization. In contrast to previous evidence, C5aR mRNA could not be detected in pulmonary or intestinal epithelial cells, whereas keratinocytes in inflamed but not in normal skin revealed detectable levels of C5aR transcripts. Additionally, it could be documented that only migrating Mphi express C5aR mRNA, whereas sessile Mphi in normal tissues and epithelioid/multinucleated Mphi found in granulomatous lesions do not. Because C5a has been demonstrated to upregulate the expression of interleukin (IL)-6 in human monocytes, we also studied IL-6 gene transcription in parallel to the C5aR. IL-6 mRNA was detectable in many tissue Mphi. Surprisingly, a tight co-expression of C5aR and IL-6 mRNA was observed in keratinocytes from lesions of pyogenic granuloma and lichen planus. These results point to an as yet unknown role for C5a in the pathogenesis of skin disorders beyond its well-defined function as a chemoattractant and activator of leukocytes.  (+info)

Experimental axonal injury triggers interleukin-6 mRNA, protein synthesis and release into cerebrospinal fluid. (8/14219)

Diffuse axonal injury is a frequent pathologic sequel of head trauma, which, despite its devastating consequences for the patients, remains to be fully elucidated. Here we studied the release of interleukin-6 (IL-6) into CSF and serum, as well as the expression of IL-6 messenger ribonucleic acid (mRNA) and protein in a weight drop model of axonal injury in the rat. The IL-6 activity was elevated in CSF within 1 hour and peaked between 2 and 4 hours, reaching maximal values of 82,108 pg/mL, and returned to control values after 24 hours. In serum, the levels of IL-6 remained below increased CSF levels and did not exceed 393 pg/mL. In situ hybridization demonstrated augmented IL-6 mRNA expression in several regions including cortical pyramidal cells, neurons in thalamic nuclei, and macrophages in the basal subarachnoid spaces. A weak constitutive expression of IL-6 protein was shown by immunohistochemical study in control brain. After injury, IL-6 increased at 1 hour and remained elevated through the first 24 hours, returning to normal afterward. Most cells producing IL-6 were cortical, thalamic, and hippocampal neurons as confirmed by staining for the neuronal marker NeuN. These results extend our previous studies showing IL-6 production in the cerebrospinal fluid of patients with severe head trauma and demonstrate that neurons are the main source of IL-6 after experimental axonal injury.  (+info)