Potential Role Of IL-6 Research Articles

Potential Role of IL-6 in Inflammatory Arthritis: A Comparative Study

Potential Role of IL-6 in Inflammatory Arthritis: A Comparative Study

Ageing and atherosclerosis: vascular intrinsic and extrinsic factors and potential role of IL-6.

The number of old people is rising worldwide, and advancing age is a major risk factor for atherosclerotic cardiovascular disease. However, the mechanisms underlying this phenomenon remain unclear. In this Review, we discuss vascular intrinsic and extrinsic mechanisms of how ageing influences the pathology of atherosclerosis. First, we focus on factors that are extrinsic to the vasculature. We discuss how ageing affects the development of myeloid cells leading to the expansion of certain myeloid cell clones and induces changes in myeloid cell functions that promote atherosclerosis via inflammation, including a potential role for IL-6. Next, we describe vascular intrinsic factors by which ageing promotes atherogenesis — in particular, the effects on mitochondrial function. Studies in mice and humans have shown that ageing leads to a decline in vascular mitochondrial function and impaired mitophagy. In mice, ageing is associated with an elevation in the levels of the inflammatory cytokine IL-6 in the aorta, which participates in a positive feedback loop with the impaired vascular mitochondrial function to accelerate atherogenesis. We speculate that vascular and myeloid cell ageing synergize, via IL-6 signalling, to accelerate atherosclerosis. Finally, we propose future avenues of clinical investigation and potential therapeutic approaches to reduce the burden of atherosclerosis in old people.

The Potential Role of IL-6 in Monitoring Coronavirus Disease 2019

Background: The outbreak of coronavirus disease 2019 (COVID-19) in Wuhan City, China spreads rapidly since December, 2019. Most patients show mild symptoms, but some of them develop into severe disease. There is currently no specific medication. The purpose of this study is to explore changes of markers in peripheral blood of severe COVID-19 patients, which may be of value in disease monitoring. Methods: Clinical data of patients with nonsevere and severe type COVID-19 diagnosed by laboratory test in our institution were collected. The relationship between peripheral blood cells and cytokines, clinical manifestation and outcome was analyzed. Results: A total of 69 severe type COVID-19 patients were included. On admission, the median age of severe cases was 56-year old, with 52.17% of female patient. The most common symptoms were fever (79.72%), coughing (63.77%), shortness of breath (57.97%) and fatigue (50.72%). Diarrhea is less common. The most common comorbidity is hypertension. Upon admission, the proportion of bilateral pulmonary involvement or interstitial pneumonia evidenced by CT imaging in severe cases was 60.87% and 27.54%, respectively. Compared with patients with nonsevere disease, those with severe disease showed lymphocytopenia. Elevated level of lactate dehydrogenase (LDH), C-reactive protein (CRP), ferritin and D-dimer was found in most cases. Two patients (2.9%) needed transfer to the intensive care unit. Baseline immunological parameters and most of the inflammatory parameters were basically within the normal range. However, baseline IL-6 was significantly increased in severe type which is closely related to the maximal body temperature during hospitalization and CT findings. Baseline IL-6 was also significantly related to the increase of baseline level of CRP, LDH, ferritin and D-dimer. The increase of baseline IL-6 level suggests that it may positively correlate with the severity of COVID-19. Among the 30 severe type patient whose level of IL-6 was assessed before and after treatment, significant decrease in IL-6 and improved CT assessment was found in 25 patients after treatment. Whereas the IL-6 level was further increased in 3 cases, which was closely related to the progression of pneumonia. It is suggested that IL-6 may be used as a biomarker for disease monitoring in severe COVID-19 patients. Conclusion: On admission, the baseline level of IL-6, CRP, LDH and ferritin was closely related to the severity of COVID-19, and the high level of IL-6 was significantly related to the clinical manifestation of severe type patients. The decrease of IL-6 was closely related to treatment effectiveness, while the increase of IL-6 indicated disease progression. Collectively, the dynamic change of IL-6 level can be used as a marker for disease monitoring in patients with severe COVID-19. Funding Statement: This work was supported by the National Natural Science Foundation of China (No. 81602696 to TL) and Science and Technology Major Project of China (No.2018ZX10302204-002-003). Declaration of Interests: All authors declare no competing interests. Ethics Approval Statement: This study was approved by the Research Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology. Written consent was obtained from patients before the enrollment.

383-P: The Potential Role of Il-6 in Defective Glucose Sensing following Recurrent Hypoglycaemia

Hypoglycaemia is common in insulin-treated therapy in the management of type 1 and long duration type 2 diabetes. Hypoglycemia evokes a significant stress response stimulating the release of several inflammatory mediators including interleukin 6 (IL-6). Importantly, glial cells also release IL-6 in response to glucose deprivation. We have previously demonstrated a role for IL-6 in the induction of defective neuronal glucose sensing in vitro. Here we investigate the potential role of IL-6 in the development of defective counter-regulatory response (CRR) to hypoglycaemia in vivo. IL-6Ra-/- mice were generated by crossing IL-6RaFlx/flx with Nestin-Cre+/-animals. Male IL-6Ra-/- and Cre+/- animals (Control) 18 weeks old, n=10/12 per group) were fed standard laboratory chow for 20 weeks. Hormonal response to hypoglycaemia was assessed in vivo by hyperinsulinaemic-hypoglycaemic clamps. Plasma epinephrine and glucagon were measured by ELISA in response to either acute (single hypo; AH) or recurrent (3 episodes per week for 4 weeks; RH) hypoglycaemia. Data are expressed as mean±SEM. The epinephrine response to hypoglycaemia was significantly elevated (>3 fold higher) in male IL-6Ra-/- animals following AH when compared to their control counterparts (0.38±0.09 vs. 1.31±0.28 delta; p<0.05). Plasma glucagon levels were comparable between genotypes (p=ns). In contrast, there was a significant suppression of the CRR to hypoglycaemia in both Control and IL-6Ra-/- animals following RH. Indeed, both IL-6Ra-/- and Control animals had suppressed epinephrine (50% and 68% reduction) and glucagon (65% and 44% reduction) responses to following RH when compared to their non-RH counterparts. These findings highlight an important role for central IL-6 signaling in response to acute hypoglycemia, however, additional mechanisms appear to contribute to the development of defective CRR following RH. Disclosure A.D. McNeilly: None. J. Gallagher: None. R.J. McCrimmon: Advisory Panel; Self; Eli Lilly and Company, Novo Nordisk A/S, Sanofi-Aventis. Research Support; Self; The Leona M. and Harry B. Helmsley Charitable Trust. Funding Diabetes UK

The Presence and involvement of interleukin-17 in apical periodontitis.

Apical periodontitis (AP) is a chronic inflammatory disease characterized by periapical tissue inflammation and destruction of the associated alveolar bone. It is caused by microbial infections within the root canal and the resultant host immune responses in the periapical tissues. The proinflammatory cytokine interleukin (IL)-17 has been shown to play an important role in many inflammatory diseases. There is increasing evidence of the presence of IL-17 in AP, which might be associated with disease pathogenesis. Moreover, several animal studies indicate the potential role of IL-17 in periapical inflammation and the resultant bone resorption in AP. This article reviews recent studies regarding the collective invitro, invivo and clinical evidence of the presence and involvement of IL-17 in AP. A search related to IL-17 in apical periodontitis was conducted on PubMed, EMBASE and Web of Science databases using keywords and controlled vocabulary. Two independent reviewers first screened titles and abstracts and then the full texts that were included. A total of 25 papers were identified, of the 25 included articles, 7 involved laboratory studies on cell cultures, 11 involved animal experimentations, and 7 were observational studies using human clinical samples. In conclusion, evidence for the presence of IL-17 in AP from human and animal models is clear. However, there is relatively little information currently available that would highlight the specific role of IL-17 in AP.

Decreased periferal blood dendritic cells in multiple Myeloma: The potential role of IL-6 and Beta-2-Microglobulin

Introduction : Several studies demonstrate the presence of quantitative and functional abnormalities in the dendritic cell (DC) subsets in patients with multiple myeloma (MM). The inhibitory effect of IL-6, TGF-!, IL-10 and beta-2-microglobuline (beta-2-MG) is highly suspected. Purpose : The aim of the study was to evaluate the myeloid and plasmacytoid dendritic cells (MDC and PDC) in newly diagnosed patients with MM in correlation with various biological markers. Materials and Methods : Thirty patients with newly diagnosed MM were included in the study. All the laboratory parameters were obtained at the time of diagnosis. Three colour flow cytometry with ILT3/lin/CD11c was used for the detection of the two peripheral blood dendritic cell (PBDC) subsets. The plasma level of IL6 was detected by ELISA (Standard Curve Range: 2-200pg/ml); the beta-2-MG- by the immunoturbidimetric test. Results : The median age of patients was 61.5 years (36-89). The mean M-protein concentration was 46.5±16.2 g/l. IgG kappa was detected in 15 patients, IgG lambda-in 4, IgA kappa-in 7, IgA lambda-in 3. The mean level of beta-2-MG was 7.0±5.7mg/l (1.82-22.49 mg/l ); beta-2-MG was used to determine the stage according to the ISS. The mean level of IL6 was 27.73±21.47pg/ml (4.6-72.5 pg/ml). The percentage of MDC and PDC was significantly lower in the periferal blood of patients with MM in comparison to healthy subjects (0.08%±0.09% vs 0.21%±0.02% and 0.04%±0.03% vs 0.16%±0.01%, respectively). A statistically significant difference was found between the percentage of MDC and PDC in the different stages. There was a negative correlation between MDC and PDC and the levels of beta-2-MG (p=0.02 and p=0.02), as well as between MDC and the IL6 levels (p=0.04). No correlation was found between MDC, PDC, levels of M-protein and the type of paraprotein. Conclusion : Our results demonstrate the relationship between peripheral blood DC, IL6 and beta-2-MG and confirm the published data for the inhibitory effect of the two factors on DC differentiation and maturation in vitro. The monitoring of beta-2-MG and IL6 may have clinical implication as a predictor of the immune system status as well as for the yield of harvested DCs for vaccination.

Inflammatory mediators after endovascular aortic aneurysm repair

ObjectiveTo evaluate patterns of inflammatory mediators before and after elective endovascular aortic aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA). Materials and methodsInflammatory mediators including soluble urokinase plasminogen activator (suPAR), endothelin (ET)-1, tumour necrosis factor (TNF)-α, interleukin (IL)-6, CD40 ligand (CD40L) and IgM antibodies against phosphorylcholine (IgM anti-PC), were evaluated before and after elective EVAR in 21 patients. Five patients undergoing open AAA repair (OR) were evaluated for comparison. ResultsSuPAR (p<0.001), ET-1 (p=0.003) and IL-6 (p=0.02) increased whereas IgM anti-PC decreased (p<0.001) after EVAR. Both suPAR (p=0.04) and IL-6 (p=0.03) increased in the five patients with unchanged/expanded aneurysm sac after EAR, whereas only suPAR increased (p=0.04) and IL-6 remained unchanged (p=0.2) among the 16 patients with shrinking aneurysm sac. No difference was noted between patients undergoing EVAR and OR regarding levels or changes of studied markers. ConclusionsThese changes in plasma biomarker profile are compatible with on-going inflammatory activation in AAA patients after EVAR. The potential role of IL-6 as a plasma biomarker for treatment failure in surveillance programs after EVAR needs to be further evaluated.

IL-6(-572/-597) polymorphism and expression in HBV disease chronicity in an Indian population.

This study evaluated the association among IL-6(-572) and IL-6(-597) genotypes, haplotypes, mRNA, and protein levels with hepatitis B virus (HBV)-Hepatocellular carcinoma (HCC) risk in India. For this, 403 participants (153 controls, 61 inactive HBV-carriers, 65 chronic-active HBV patients, 63 HBV-cirrhotics, and 61 HBV-HCC participants) were enrolled in the study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), ELISA, and RT-PCR methods were used for assessing polymorphism, protein, and the mRNA levels, respectively, of IL-6. The study revealed that the IL-6(-572) GC genotype shared a positive association with hepatitis among controls, and a negative association with cirrhosis and consequent HCC development among carriers. However, the CC genotype shared a significant negative association with cirrhosis among controls and carriers. The IL-6(-597G>A), GA genotype acted as a potential protective factor for hepatitis, cirrhosis, and subsequent HCC development among carriers. The GA and CG haplotypes acted as a vital risk factor for HCC among controls and carriers. On the contrary, the CA haplotype was found to be a potential protective factor for HCC among carriers. Besides, the IL-6 levels significantly increased with cirrhosis development, as compared to carriers and hepatitis subjects. These preliminary findings indicate a potential role of IL-6(-572/-597) genotypes in HBV disease pathogenesis in an Indian population.

The presence, function and regulation of IL‐17 and Th17 cells in periodontitis

Periodontitis (PD) is a chronic inflammatory disease characterised by tissue inflammation and destruction of the associated alveolar bone. It is caused by the colonisation of the bacterial plaque biofilm and the resultant host immune responses in the surrounding periodontal tissues. The pro-inflammatory cytokine IL-17, and IL-17 producing CD4+ T cells (also called Th17 cells) have been shown to play an important role in many inflammatory diseases. There is increasing evidence of the presence of IL-17 and Th17 cells in human PD lesions and this may be associated with disease severity. Moreover, several animal studies indicate the potential role of IL-17 and Th17 cells in gingival inflammation and the resultant bone destruction in PD. Here we review recent findings regarding the presence, function and regulation of IL-17 and Th17 cells in PD, and we highlight potential areas of future research interest.

Paradoxical Tuberculosis Immune Reconstitution Inflammatory Syndrome (TB-IRIS) in HIV Patients with Culture Confirmed Pulmonary Tuberculosis in India and the Potential Role of IL-6 in Prediction

BackgroundThe incidence, manifestations, outcome and clinical predictors of paradoxical TB-IRIS in patients with HIV and culture confirmed pulmonary tuberculosis (PTB) in India have not been studied prospectively.MethodsHIV+ patients with culture confirmed PTB started on anti-tuberculosis therapy (ATT) were followed prospectively after anti-retroviral therapy (ART) initiation. Established criteria for IRIS diagnosis were used including decline in plasma HIV RNA at IRIS event. Pre-ART plasma levels of interleukin (IL)-6 and C-reactive protein (CRP) were measured. Univariate and multivariate logistic regression models were used to evaluate associations between baseline variables and IRIS.ResultsOf 57 patients enrolled, 48 had complete follow up data. Median ATT-ART interval was 28 days (interquartile range, IQR 14–47). IRIS events occurred in 26 patients (54.2%) at a median of 11 days (IQR: 7–16) after ART initiation. Corticosteroids were required for treatment of most IRIS events that resolved within a median of 13 days (IQR: 9–23). Two patients died due to CNS TB-IRIS. Lower CD4+ T-cell counts, higher plasma HIV RNA levels, lower CD4/CD8 ratio, lower hemoglobin, shorter ATT to ART interval, extra-pulmonary or miliary TB and higher plasma IL-6 and CRP levels at baseline were associated with paradoxical TB-IRIS in the univariate analysis. Shorter ATT to ART interval, lower hemoglobin and higher IL-6 and CRP levels remained significant in the multivariate analysis.ConclusionParadoxical TB–IRIS frequently complicates HIV-TB therapy in India. IL-6 and CRP may assist in predicting IRIS events and serve as potential targets for immune interventions.

Molecular mechanisms of anti-tumor properties of P276-00 in head and neck squamous cell carcinoma

BackgroundTumors of the head and neck present aggressive pathological behavior in patients due to high expression of CDK/CCND1 proteins. P276-00, a novel CDK inhibitor currently being tested in clinic, inhibits growth of several cancers in vitro and in vivo. The pre clinical activity of P276-00 in head and neck cancer and its potential mechanisms of action at molecular level are the focus of the current studies.MethodWe have investigated the anti-cancer activity of P276-00 in head and neck tumors in vitro and in vivo. Candidate gene expression profiling and cell based proteomic approaches were taken to understand the pathways affected by P276-00 treatment.ResultsIt was observed that P276-00 is cytotoxic across various HNSCC cell lines with an IC50 ranging from 1.0-1.5 μmoles/L and culminated in significant cell-cycle arrest in G1/S phase followed by apoptosis. P276-00 treatment suppressed cell proliferation through inhibition of CCND1 expression, reduced phosphorylation of retinoblastoma protein and abrogative transcription of E2F1 gene targets. Further, we observed that apoptosis was mediated through P53 activation leading to higher BAX/BCL-2 ratio and cleaved caspase-3 levels. It was also seen that P276-00 treatment reduced expression of tumor micro-environment proteins such as IL-6, secreted EGFR and HSPA8. Finally, P276-00 treatment resulted in significant tumor growth inhibition in xenograft tumor models via lowered proliferative activity of E2F1 and aggravated P53 mediated apoptosis.ConclusionIn summary, we have observed that P276-00 inhibits cyclin-D/CDK4/P16/pRB/E2F axis and induces apoptosis by increased P53 phosphorylation in HNSCC cells. These results suggest a novel indication for P276-00 in head and neck cancer with a potential role for IL-6 and HSPA8 as candidate serum biomarkers.

Interleukin-17A Increases Neurite Outgrowth from Adult Postganglionic Sympathetic Neurons

Inflammation can profoundly alter the structure and function of the nervous system. Interleukin (IL)-17 has been implicated in the pathogenesis of several inflammatory diseases associated with nervous system plasticity. However, the effects of IL-17 on the nervous system remain unexplored. Cell and explant culture techniques, immunohistochemistry, electrophysiology, and Ca2+ imaging were used to examine the impact of IL-17 on adult mouse sympathetic neurons. Receptors for IL-17 were present on postganglionic neurons from superior mesenteric ganglia (SMG). Supernatant from activated splenic T lymphocytes, which was abundant in IL-17, dramatically enhanced axonal length of SMG neurons. Importantly, IL-17-neutralizing antiserum abrogated the neurotrophic effect of splenocyte supernatant, and incubation of SMG neurons in IL-17 (1 ng/ml) significantly potentiated neurite outgrowth. The neurotrophic effect of IL-17 was accompanied by inhibition of voltage-dependent Ca2+ influx and was recapitulated by incubation of neurons in a blocker of N-type Ca2+ channels (ω-conotoxin GVIA; 30 nM). IL-17-induced neurite outgrowth in vitro appeared to be independent of glia, as treatment with a glial toxin (AraC; 5 μM) did not affect the outgrowth response to IL-17. Moreover, application of the cytokine to distal axons devoid of glial processes enhanced neurite extension. An inhibitor of the NF-κB pathway (SC-514; 20 μM) blocked the effects of IL-17. These data represent the first evidence that IL-17 can act on sympathetic somata and distal neurites to enhance neurite outgrowth, and identify a novel potential role for IL-17 in the neuroanatomical plasticity that accompanies inflammation.

A potential role of IL-6 in the chito-oligosaccharide-mediated inhibition of adipogenesis

Recent studies have suggested that chito-oligosaccharides can have anti-adipogenic properties. The objectives of the present study were to evaluate the anti-adipogenic potential of four different chito-oligosaccharides (molecular weight (MW) < 1000, 1000-3000, 3000-5000 and 5000-10,000 Da) and to identify molecular mechanisms underlying the chito-oligosaccharide-mediated inhibition of adipogenesis. Mouse 3T3-L1 cells were allowed to differentiate in the presence of chito-oligosaccharide. At day 8 post-induction of differentiation, lipid accumulation, free glycerol release and the quantitative expression of adipogenic marker genes were evaluated. Chito-oligosaccharides had concentration- and MW-dependent inhibitory effects on lipid accumulation (P < 0·001 and < 0·05, respectively), as well as a concentration-dependent effect (P < 0·001) on free glycerol release and the expression of adipogenic marker genes. The 5000-10,000 Da chito-oligosaccharide was selected for subsequent molecular studies. A panel of forty-four lipid metabolic pathway-specific genes was analysed by quantitative real-time PCR. Chito-oligosaccharide-mediated inhibition of adipogenesis was associated with the up-regulation of the IL-6 gene at all concentrations of chito-oligosaccharide examined and the PG-endoperoxide synthase 2 (PTGS2) gene at higher concentrations of chito-oligosaccharide. The effect of chito-oligosaccharide on gene expression was validated by measuring IL-6 protein concentrations in the media. Finally, an IL-6 promoter assay was developed to characterise the effect of chito-oligosaccharide on the transcriptional activity of the IL-6 promoter, which was increased in a concentration-dependent manner (P < 0·001). We conclude that IL-6 is a candidate signalling molecule in the chito-oligosaccharide-mediated inhibition of adipogenesis in 3T3-L1 cells.

Abstract 1209: Interleukin-6 Reduces Myocardial Glucose Metabolism by Altering AMPK, Insulin Signaling, and PKC-𝛉 in Mice

Increasing evidence implicates the role of inflammation in the pathogenesis of diabetes and complications. Inflammatory cytokines (IL-6, TNF-α) are elevated in obese diabetic subjects, and are shown to modulate glucose metabolism in peripheral organs. In this report, we examined the effects of IL-6 on cardiac metabolism and insulin action in vivo. Male C57BL/6 mice were intravenously treated with IL-6 (16 ng/hr) or saline (control) for 2 hrs, and [ 14 C]2-deoxyglucose was intravenously injected in awake mice to measure myocardial glucose metabolism (n=9~10). Hyperinsulinemic-euglycemic clamps (2.5 mU/kg/min insulin infusion) were also performed in IL-6 or saline-treated mice (n=4~5) to measure cardiac insulin action. Acute treatment with IL-6 caused a 25% increase in myocardial STAT3 activity and significantly reduced basal myocardial glucose metabolism (Fig. 1 ; * P&lt; 0.05). IL-6 treatment also reduced insulin-stimulated glucose uptake in heart, and these effects were associated with marked decreases in AMPK activity (Thr-phosphorylation of AMPK; Fig. 2 ) and IRS-1 tyrosine phosphorylation (Fig. 3 ). Acute IL-6 treatment increased myocardial expression of PKC-𝛉, which has been shown to mediate insulin resistance in peripheral organs (Fig. 4 ). These results indicate that IL-6 is a potent negative regulator of myocardial glucose metabolism and insulin action, and the underlying mechanism may involve IL-6 mediated activation of PKC-𝛉 and defects in AMPK and insulin signaling activity. Thus, our findings suggest a potential role of IL-6 in the pathogenesis of diabetic heart failure.

IL-17 Enhances the Net Angiogenic Activity and In Vivo Growth of Human Non-Small Cell Lung Cancer in SCID Mice through Promoting CXCR-2-Dependent Angiogenesis

In this study, we examined the biological action of IL-17 on human non-small cell lung cancer (NSCLC). Although IL-17 had no direct effect on the in vitro growth rate of NSCLC, IL-17 selectively augmented the secretion of an array of angiogenic CXC chemokines, including CXCL1, CXCL5, CXCL6, and CXCL8 but not angiostatic chemokines, by three different NSCLC lines. Endothelial cell chemotactic activity (as a measure of net angiogenic potential) was increased in response to conditioned medium from NSCLC stimulated with IL-17 compared with those from unstimulated NSCLC. Enhanced chemotactic activity was suppressed by neutralizing mAb(s) to CXCL1, CXCL5, and CXCL8 or to CXCR-2 but not to vascular endothelial growth factor-A. Transfection with IL-17 into NSCLC had no effect on the in vitro growth, whereas IL-17 transfectants grew more rapidly compared with controls when transplanted in SCID mice. This IL-17-elicited enhancement of NSCLC growth was associated with increased tumor vascularity. Moreover, treatment with anti-mouse CXCR-2-neutralizing Ab significantly attenuated the growth of both neomycin phosphotransferase gene-transfected and IL-17-transfected NSCLC tumors in SCID mice. A potential role for IL-17 in modulation of the human NSCLC phenotype was supported by the findings that, in primary NSCLC tissues, IL-17 expression was frequently detected in accumulating and infiltrating inflammatory cells and that high levels of IL-17 expression were associated with increased tumor vascularity. These results demonstrate that IL-17 increases the net angiogenic activity and in vivo growth of NSCLC via promoting CXCR-2-dependent angiogenesis and suggest that targeting CXCR-2 signaling may be a novel promising strategy to treat patients with NSCLC.

Sleep–wake behavior and responses of interleukin-6-deficient mice to sleep deprivation

Interleukin (IL)-1 and tumor necrosis factor (TNF) are involved in the regulation of non-rapid eye movements sleep (NREMS). Accumulating evidence suggests IL-6 modulates sleep under some pathophysiologic conditions. We used mice lacking a functional IL-6 gene to investigate further a potential role for IL-6 in the regulation of sleep. IL-6 knockout mice (B6.129S6- Il6 tm1 Kopf ; n=10) and C57BL/6J mice ( n=10) were purchased from the Jackson Laboratory (Bar Harbor, ME). Twenty-four-hour baseline recordings were obtained from mice in the absence of any experimental manipulation. Mice were then subjected to 6-h sleep deprivation beginning at light onset. Recordings were obtained during the deprivation period and for 18 h thereafter. During baseline conditions there were no differences between mouse strains with respect to the duration, timing or intensity of NREMS. However, across the 24-h recording period IL-6 knockout mice spent approximately 30% more time in rapid eye movements sleep (REMS) than did C57BL/6J mice. Relative to C57BL/6J mice, core body temperatures of IL-6 knockout mice were higher during the light period of the light:dark cycle. Both strains responded to sleep deprivation by spending more time in NREMS and REMS. Although the total increase in the amount of NREMS after sleep deprivation was the same in both strains, IL-6 knockout mice took 6 h longer to accumulate this additional sleep. Under the conditions of this study, IL-6 does not appear necessary for the full manifestation of NREMS, although this cytokine may influence the dynamics of responses to sleep deprivation. That mice lacking IL-6 spend more time in REMS suggests that interactions between IL-6 and REMS regulatory mechanisms may differ from those of IL-1 and/or TNF.

Characterization of the role of IL-6 in the progression of prostate cancer.

We recently identified IL-6, a pleiotropic cytokine implicated in the neoplastic process of a variety of neoplasms, as a mediator of prostate cancer morbidity. In the present study, we investigated the expression of members of the IL-6 supergene family and related cytokines and the potential role of IL-6 in prostate cancer growth regulation. Five established human prostate cancer cell lines were screened by ELISA for production of granulocyte colony-stimulating factor (G-CSF), leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), oncostatin M (OSM), tumor necrosis factor (TNF), interleukin-1 (IL-1), and granulocyte macrophage colony-stimulating factor (GM-CSF). Expression of the ligand-binding component of the IL-6 receptor, IL-6Rp80, was evaluated by ELISA and RT-PCR. Sequential immunoprecipitation and immunoblotting were performed to assay for expression of the signal-transducing component of the IL-6 receptor, gp130. The effects of IL-6 on cell growth were assessed by MTT assays. The three hormone-refractory cell lines, DU-145, TSU, and PC-3, secreted distinct combinations of cytokines (DU-145: IL-6, GM-CSF; TSU: IL-6, LIF; PC-3: IL-6, G-CSF, LIF, IL-1, GM-CSF), each uniformly expressing IL-6. In contrast, neither of the two hormone-dependent cell lines, LNCaP-ATCC and LNCaP-GW, secreted significant quantities of any of the cytokines analyzed. None of the cell lines secreted detectable quantities of OSM, CNTF, or TNF. All cell lines, irrespective of hormone status, expressed both Il-6Rp80 and gp130. Addition of IL-6 in vitro inhibited growth of hormone-dependent cells, but had no effect on hormone-refractory lines. Anti-IL-6 neutralizing antibody inhibited growth of hormone-refractory cells. IL-6 appears to undergo a functional transition from paracrine growth inhibitor to autocrine growth stimulator during progression of prostate cancer to the hormone-refractory phenotype.

Effect of IL-6 on Alveolar Fibroblast Proliferation in Interstitial Lung Diseases

Alveolar macrophage–fibroblast interaction may be involved in the pathogenesis of interstitial lung diseases (ILD). Herein, we compared IL-6 secretion from alveolar macrophages (AM) and alveolar fibroblasts (AFb) recovered from patients with sarcoidosis (SA) and with diffuse interstitial fibrosis (DIF). Moreover, we evaluated the effect of IL-6 on thein vitroAFb proliferation in both diseases. AM and AFb from SA patients showed increased spontaneous secretion of IL-6 compared with cells from DIF subjects. Tumor necrosis factor-α (TNFα) and interleukin-1 (IL-1) enhanced IL-6 secretion and IL-6 mRNA transcription in AFb of SA patients. Addition of anti-IL-6 MoAbs increased AFb proliferation capacity in SA, but suppressed it in DIF. These results show that only SA AM and AFb secrete high levels of IL-6 which have suppressive effect on AFb proliferation. This may indicate a potential role of IL-6 in the fibrogenesis of ILD.

The murine Il-6 gene maps to the proximal region of chromosome 5.

Murine Il-6 cDNAs were isolated by cross-hybridization with a human IL-6 cDNA from an IL-1 activated bone marrow stromal cell line (W20). Mouse-hamster somatic cell hybrids were utilized to localize murine Il-6 to chromosome 5. Genetic mapping with respect to En-2, AlbH, and Gus in backcross progeny from an interspecific mating between C57BL/6J and Mus spretus positioned Il-6 3 cM distal to En-2. The syntenic relationships of Il-6 and En-2 in mouse and man, as well as the potential role of IL-6 in tumorigenesis, are discussed.