Interleukin 6 (IL-6)

Gene Association with Leprosy: A Review of Published Data

Leprosy is a chronic infectious disease caused by an obligate intracellular bacterium known as Mycobacterium leprae. Exposure to the bacillus is necessary, but this alone does not mean an individual will develop clinical symptoms of the disease. In recent years, several genes have been associated with leprosy and the innate immune response pathways converge on the main hypothesis that genes are involved in the susceptibility for the disease in two distinct steps: for leprosy per se and in the development of the different clinical forms. These genes participate in the sensing, main metabolic pathway of immune response activation and, subsequently, on the evolution of the disease into its clinical forms. The aim of this review is to highlight the role of innate immune response in the context of leprosy, stressing their participation in the signaling and targeting processes in response to bacillus infection and on the evolution to the clinical forms of the disease.

[Glycan ligand specificity of killer lectin receptors]

Sialyl Lewis X (sLeX) antigen, Neu5Acα2,3Galβ1,4(Fucα1,3)GlcNAc-R, is expressed on the glycoproteins in sera or the surface of the cells and the expression of sLeX is enhanced in various conditions such as the inflammation and cancer. SLeX in the serum is utilized as a tumor marker. To clarify the roles of sLeX on secreted glycoproteins in vivo, we investigate the regulation of natural killer (NK) cell-dependent cytotoxicity through sLeX. NK cells express many receptors to kill the target cells such as cancerous cells and non-self, and their protein ligands have been elucidated. Of the killer lectin-like receptors (KLRs) on NK cells, several have been reported to recognize glycans. Using recombinant extracellular domains of KLRs (rKLRs: rNKG2A, C, D and rCD94), we evaluated their glycan ligand specificity and binding affinities using EIA methods. We clarified that all of these rKLRs can bind to high sLeX-expressing glycoprotein and heparin, heparan sulfate and highly sulfated polysaccharides and that glycan binding sites on NKG2D are mostly overlapped with those of protein ligands. In this review, we show the recent findings concerning the glycan ligands of these KLRs.

IL-6 protects pancreatic islet beta cells from pro-inflammatory cytokines-induced cell death and functional impairment in vitro and in vivo

Protection of pancreatic islet beta cells from pro-inflammatory cytokines-induced cell death and functional impairment is a key issue in developing therapeutic interventions of type 1 diabetes mellitus including islet transplantation. The effects of IL-6 on the protection of beta cells in vitro and in vivo were examined. Freshly isolated islets or MIN6 beta cells, when pre-incubated with IL-6, showed significantly higher viabilities measured by MTT assay and FACS analysis of PI stained cells against pro-apoptotic signaling delivered by IL-1beta, TNF-alpha and IFN-gamma. Insulin secretory function was also significantly protected in static culture with glucose and KCl stimulation. In vivo assessment using marginal mass syngeneic islet transplantation in mouse model revealed IL-6 conferred significantly better blood glucose control and graft survival rate over 50 days. Conclusively, IL-6 protects pancreatic islets or beta-cells from inflammatory cytokines-induced cell death and functional impairment both in vitro and in vivo. This strategy could be exploited in the clinical setting to maintain functional islet mass.

Co-operative functions between nuclear factors NFkappaB and CCAT/enhancer-binding protein-beta (C/EBP-beta) regulate the IL-6 promoter in autocrine human prostate cancer cells

BACKGROUND

IL-6 is a growth and survival factor for prostate cancer cells through autocrine pathways. Here, we have systematically examined the transcriptional regulation mechanisms of IL-6 in autocrine prostate cancer cells.

METHODS

RT-PCR and immunohistochemical staining were used to determine IL-6 production in the cells. Serial mutant IL-6 promoter luciferase reporters were generated and their transcriptional activities were examined. The transcription factors involved in IL-6 regulation were identified with super-shift EMSA. Overexpression of NFkappaB p65 and C/EBP-beta, and blockade of NFkappaB with IkappaBalpha or CAPE were performed to demonstrate the cooperation between NFkappaB p65 and C/EBP-beta in activation of IL-6.

RESULTS

Transcription factor regulatory sites IL6-NFkappaB, IL6-C/EBP, IL6-CREB, and IL6-AP1, are responsive to constitutively activated IL-6 production in autocrine prostate cancer cell lines. Among these sites, IL6-AP1 and IL6-C/EBP appear most important, while IL6-NFkappaB shows the least effect for IL-6 promoter activity as determined by mutant IL-6 promoter luciferase reporter assay. Nevertheless, nuclear factor NFkappaB is activated and required. Such activation is minimally dependent upon the IL6-NFkappaB site, occurring through cooperation with other transcription factors that bind the IL-6 promoter. Cooperation between NFkappaB p65 and C/EBP-beta did not require a functional IL6-NFkappaB binding site.

CONCLUSIONS

These data support a unique role for NFkappaB p65 as the primary trigger in autocrine production of IL-6 in prostate cancer cells. Furthermore, we describe a novel transcriptional activation mechanism for NFkappaB that is independent of its regulatory binding site, occurring through cooperation with other transcription factors that facilitate the neighboring regulatory site.

Elevated pretreatment serum levels of Il-10 are associated with a poor prognosis in Hodgkin's disease, the milan cancer institute experience

Alterated cytokine secretion may play a role in determining Hodgkin's disease-related immunosuppression. The aim of this study was to analyze the clinical significance of interleukin-10 (IL-10) serum levels in 73 chemotherapy-naive patients with Hodgkin's disease. We evaluated the relationship between pretreatment circulating values of IL-10 and both the clinical characteristics of the disease as well as the prognosis in terms of freedom from progression and overall survival. Abnormally high pre-treatment serum levels (mean+/-standard error: 26.79+/-13.24 pg/ml) were detected in 33/73 (45%) patients. The percentage of patients with enhanced IL-10 secretion was significantly higher in the presence of advanced disease (56% vs 32%, P<0.03), systemic symptoms (57% vs 34%, P<0.04) and more than 3 involved sites (61% vs 36%, P<0.03). The high basal levels of IL-10 negatively influenced long-term results: at 8-years freedom from progression (FFP) and overall survival (OS) for patients with IL-10>6 pg/ml vs Collapse

Key Words Collapse

MESH Headings

• Adolescent
• Adult
• Biomarkers, Tumor/blood
• Disease Progression
• Female
• Hodgkin Disease/immunology
• Hodgkin Disease/pathology
• Humans
• Interleukin-10/blood
• Male
• Middle Aged
• Predictive Value of Tests
• Prognosis
• Retrospective Studies
• Survival Analysis

Collapse

Grants Collapse

Affiliation(s)

S Viviani Division of Medical Oncology A, Istituto Nazionale Tumori 20133, Milano, Italy
P Notti
V Bonfante
P Verderio
P Valagussa
G Bonadonna

Collapse

Soluble interleukin-2 receptors (sIL-2R) in Hodgkin's disease: outcome and clinical implications

The aim of this study was to assess the prognostic role of soluble interleukin-2 receptors (sIL-2R) in Hodgkin's disease (HD) both in the achievement of complete remission (CR) and in predicting disease relapse. Between August 1988 and June 1993 sIL-2R serum levels were measured in 174 untreated patients; in 137 of them evaluation was repeated at the end of treatment and in 132 also during the follow-up. Baseline sIL-2R levels (mean+/-standard error) were significantly higher in patients than in 65 healthy control subjects (1842+/-129 U ml(-1) vs 420+/-10 U ml(-10, P< 0.0001). At the end of treatment 135 out of 137 evaluated patients achieved complete response (CR) and their mean sIL-2R serum levels were significantly lower than those at diagnosis (635+/-19 U ml(-1) vs 1795+/-122 U ml(-1), P=0.0001). After a median follow-up of 5 years, sIL-2R remained low in 114 patients in continuous CR, while they increased in 9 out of 12 patients (75%) who relapsed. However, a temporary increase was also observed in six patients (5%) still in CR. Treatment outcome in terms of freedom from progression was linearly related to sIL-2R levels. Our study confirms that patients with untreated HD have increased baseline levels of sIL-2R compared with healthy subjects and that their pretreatment values may be an indication of disease outcome similar to other conventional prognostic factors, such as number of involved sites, presence of B symptoms and extranodal extent.

Interleukin-12 in early or advanced cancer patients

Interleukin-2 (IL-2) and interleukin-12 (IL-12) may represent the most important antitumour cytokines in human neoplasms. IL-2 blood levels decrease in advanced solid malignancies, but currently there are no data on IL-12 secretion in cancer patients. This study was performed to obtain preliminary data about IL-12 secretion in patients with solid malignant tumours, either in relation to the extension of disease, or to other cytokines, including IL-2, IL-6 and IL-10. The study included 40 solid cancer patients, 24 of whom showed distant organ metastases. Cytokine serum levels were measured by an enzyme immunoassay of blood samples collected during the morning. No patient had abnormally low levels of IL-12, but the levels were high in 14/14 (35%) patients. Mean levels of IL-12 were significantly higher in metastatic patients compared with non-metastatic patients (P < 0.05). Moreover, metastatic patients with high blood concentrations of IL-12 showed significantly lower levels of IL-10 than metastatic patients with normal IL-12 values, while no difference was seen in IL-2 mean concentrations. IL-6 mean levels were lower in metastatic patients with increased IL-12 levels, but this was non-significant. This preliminary study shows that advanced solid cancers are not characterised by a diminished secretion of IL-12, but rather IL-12 levels tend to be abnormally high in metastatic cancer patients.

Response of serum cytokines in patients undergoing laparoscopic cholecystectomy

The clinical observation that a laparoscopic cholecystectomy is a minimally invasive operation has not been demonstrated on a biochemical basis. Interleukin-6, a known endogenous pyrogen and hepatocyte-stimulating protein, correlates with the significance of surgical trauma. Utilizing the IL-6 immunoassay, we studied this biochemical parameter of trauma to compare its response in laparoscopic vs open cholecystectomy. Sixteen patients who underwent only laparoscopic cholecystectomy showed peak IL-6 concentrations of 51 pg/ml (22-86) vs a peak IL-6 concentration of 124 pg/ml (56-225) for open cholecystectomy. Six additional patients who underwent an ERCP followed by laparoscopic cholecystectomy showed a dramatic rise in peak IL-6 concentration to 315 pg/ml (15-634). These results biochemically confirm the true minimal invasiveness of laparoscopic cholecystectomy. The findings in the ERCP-followed-by-laparoscopic-cholecystectomy group support the theory that two invasive procedures in close proximity may prime the cytokine system in its response to surgical trauma.

Interleukin-6 production in a murine model of Pneumocystis carinii pneumonia: relation to resistance and inflammatory response

The production of interleukin-6 (IL-6) and its possible relationship to host resistance and inflammatory response to Pneumocystis carinii infection were examined in mice with severe combined immunodeficiency (SCID mice). IL-6 activity was detected in the serum and lungs of P. carinii-infected mice but not in mice free of P. carinii. Moreover, the IL-6 levels in P. carinii-infected mice increased markedly after spleen cell reconstitution but then decreased to an undetectable level after the clearance of P. carinii. However, neutralization of IL-6 activity in spleen cell-reconstituted SCID mice by treatment with anti-IL-6 immunoglobulin G (IgG) resulted in no significant effect on the clearance of P. carinii (P > 0.05). Both the serum and lungs of treated mice contained an excess amount of anti-IL-6 IgG and lacked detectable IL-6. These results suggest that failure to inhibit the P. carinii clearance by anti-IL-6 treatment was not due to insufficient administration of antibody or incomplete neutralization of IL-6 activity. However, compared with mice receiving rat control IgG, mice treated with anti-IL-6 IgG had significantly higher numbers of neutrophils and lymphocytes (particularly CD8+ cells) in the lung lavage fluids (P < 0.05 for both) at day 19 after reconstitution. In addition, the levels of both total IgG (P < 0.001) and P. carinii-specific antibodies (P < 0.05) in the serum of mice treated with anti-IL-6 were significantly higher than those in control mice. These results indicate that although P. carinii infection causes both local and systemic production of IL-6 in SCID mice, IL-6 does not appear to play a crucial role in the clearance of P. carinii. However, it appears that during resolution of P. carinii pneumonia, IL-6 plays a role in the regulation of pulmonary inflammation and antibody responses.

Tumor necrosis factor. Characterization at the molecular, cellular and in vivo level

TNF was originally characterized as an antitumor agent and a factor cytotoxic for many malignant cells. It is now clear that it plays an important role in the defense against viral, bacterial and parasitic infections, - and in (auto-)immune responses. Natural induction of TNF is protective, but its overproduction may be detrimental and even lethal to the host. The structure of TNF and its interaction with the two types of cellular receptor are becoming better understood. TNF elicits a variety of events in different cell types. It subverts the electron transport system or the mitochondria into production of oxygen radicals, which can kill the (malignant) cells when these do not contain or produce protective enzymes. Furthermore, TNF induces a set of genes and at least part of this transcriptional activation is mediated by NF kappa B. The prospects of TNF as an antitumor drug can be improved on the one hand by agents such as LI+, which synergizes, and on the other hand by inhibitors of the systemic toxicity which do not interfere with the antitumor efficacy. Also, in tumor-bearing animals which have been rendered tolerant by administration of small doses of TNF, an effective and complete elimination of the tumors can be obtained by the combined action of TNF plus interferon.