IL-6 Expression In Monocytes Research Articles

GW29-e1996 Long noncoding RNA CTB-41I6.2 positively regulates LPS-induced IL6 expression in monocytes

GW29-e1996 Long noncoding RNA CTB-41I6.2 positively regulates LPS-induced IL6 expression in monocytes

0300 STRESS SYSTEM DYSREGULATION IN INSOMNIA DISORDER

Insomnia disorder (ID) is highly co-morbid with chronic pain conditions. Dysregulation of the hypothalamus-pituitary adrenal (HPA) stress system suggests a contribution to both ID and chronic pain. We investigated HPA system integrity in individuals with ID, indicated by measures of resting cortisol levels and IL-6 expression in monocytes, glucocorticoid (GC) sensitivity (i.e., sensitivity of cells to the counter-inflammatory signal cortisol), and reactivity of cortisol to a repeated challenge. We hypothesized deterioration of HPA system integrity may represent a mechanistic pathway by which ID increases chronic pain vulnerability. This is an ongoing study with N=19 participants (ages 18–49). Seven participants (1 male) diagnosed of insomnia disorder (ID) based on DSM-V criteria and 12 healthy controls (HC;3 male) completed an overnight polysomnographic (PSG) sleep recording in the Clinical Research Center. The following morning, resting blood samples were collected for measurements of basal serum cortisol levels, IL-6 positive monocytes, and GC sensitivity of monocytes as assessed by flow cytometry. To determine serum cortisol reactivity, participants completed a cold pressor test (CPT) challenge three times in succession (1300,1430,1600) by placing their hand in a temperature-controlled cold water bath for at least one minute. Blood was drawn 20 and 50 minutes after each CPT to measure post-challenge cortisol levels. ID participants had significantly shorter PSG sleep duration (ID:341 ± 110 min; HC:422 ± 31 min). Basal cortisol levels, IL-6 positive monocytes and GC sensitivity did not differ between groups, but cortisol levels in the ID group were significantly higher 20 min (ID:14.24 ± 3.34μg/dL; HC:10.86 ± 2.38μg/dL) and 50 min (ID:11.46 ± 2.40μg/dL; HC:8.99 ± 2.04μg/dL) after the first CPT challenge, and 20 min after the second CPT challenge (ID:11.24 ± 3.59; HC:7.92 ± 1.59μg/dL). While basal levels of cortisol, IL-6 expression by monocytes, and GC sensitivity did not significantly differ between ID and HC cortisol reactivity in the first and second CPT challenge was increased. These preliminary results suggest a stronger stress system responsiveness to novel challenges, which may mechanistically contribute to the relationship between ID and vulnerability to chronic pain. Investigator-initiated grant from Merck Inc., NIH/UL1 RR02758 and M01-RR-01032 from National Center for Research Resources to Harvard Clinical and Translational Science Center.

Repeating patterns of sleep restriction and recovery: Do we get used to it?

Despite its prevalence in modern society, little is known about the long-term impact of restricting sleep during the week and ‘catching up’ on weekends. This common sleep pattern was experimentally modeled with three weeks of 5 nights of sleep restricted to 4h followed by two nights of 8-h recovery sleep. In an intra-individual design, 14 healthy adults completed both the sleep restriction and an 8-h control condition, and the subjective impact and the effects on physiological markers of stress (cortisol, the inflammatory marker IL-6, glucocorticoid receptor sensitivity) were assessed. Sleep restriction was not perceived to be subjectively stressful and some degree of resilience or resistance to the effects of sleep restriction was observed in subjective domains. In contrast, physiological stress response systems remain activated with repeated exposures to sleep restriction and limited recovery opportunity. Morning IL-6 expression in monocytes was significantly increased during week 2 and 3 of sleep restriction, and remained increased after recovery sleep in week 2 (p<0.05) and week 3 (p<0.09). Serum cortisol showed a significantly dysregulated 24h-rhythm during weeks 1, 2, and 3 of sleep restriction, with elevated morning cortisol, and decreased cortisol in the second half of the night. Glucocorticoid sensitivity of monocytes was increased, rather than decreased, during the sleep restriction and sleep recovery portion of each week. These results suggest a disrupted interplay between the hypothalamic-pituitary-adrenal and inflammatory systems in the context of repeated exposure to sleep restriction and recovery. The observed dissociation between subjective and physiological responses may help explain why many individuals continue with the behavior pattern of restricting and recovering sleep over long time periods, despite a cumulative deleterious physiological effect.

Down-regulation of inflammation-protective microRNAs 146a and 212 in monocytes of patients with postpartum psychosis

Postpartum psychosis (PP) is thought to belong to the bipolar spectrum. Recently we described an immune activation signature in monocytes of patients with PP using gene expression profiling. Immune activation genes are regulated by microRNAs (miRNAs). We therefore profiled miRNA expression in monocytes of PP patients to identify differentially expressed miRNAs between PP and the healthy state. In a profiling study we carried out miRNA profiling using TaqMan array human microRNA A cards v2.0 and monocytes of 8 PP patients. Data were analyzed against monocytes of healthy postpartum women (CP). Nine miRNAs were selected and tested using individual Q-PCR in a larger validation study on monocytes of 20 PP patients, 20 CP and 20 healthy non-postpartum women (HC). In the validation study miR-146a expression was significantly down-regulated in the monocytes of first onset PP patients as compared to CP and HC; miR-212 expression was significantly down-regulated in PP patients with prior bipolar disorder. In silico miR-146a targeted 4 genes of the previously described monocyte activation signature in bipolar disorder; miR-212 targeted 2 of such genes. In a correlation study decreased expression of miR-146a in monocytes was related to decreased natural T regulator cells in PP patients; decreased miR-212 was correlated to increased Adrenomedulin and decreased IL-6 expression in monocytes and to higher Th2 cell levels. This study identified changes in miR-146a and -212 expression in PP. Since these miRNAs are linked to inflammation, the study strengthens the view that PP is an inflammation-like condition.

The isoflavone genistein inhibits LPS-stimulated TNFa, but not IL-6 expression in monocytes from hemodialysis patients and healthy subjects

Whole blood and peripheral blood mononuclear cells from hemodialysis (HD) patients show increased production and secretion of inflammatory cytokines. We determined the contribution of blood monocytes to the production of inflammatory cytokines in whole blood from HD patients. Whole blood and isolated mononuclear cells from HD patients and healthy control subjects were preincubated with the isoflavone genistein and stimulated with LPS. TNFalpha, IL-6 and IL-10 formation in the whole blood was measured with ELISA and intracellular cytokine formation in CD 14-positive monocytes was determined by flow cytometry. Unstimulated blood levels of TNFalpha, IL-6 and IL-10 were significantly elevated in HD patients compared to controls, but intracellular monocyte content of these cytokines was identical between groups. LPS induced a robust TNFalpha response in both whole blood and monocytes, and TNFalpha formation was 2.3-fold higher in blood from HD patients compared to controls. A similar trend was observed in monocytes. Conversely, LPS stimulation increased IL-6 levels >1000-fold in whole blood, albeit without a noticeable difference between groups. Only minor increases in monocyte IL-6 content were observed. The isoflavone genistein did not inhibit IL-6 formation and did not alter basal TNFalpha levels, but genistein selectively blocked LPS-induced TNFalpha formation in whole blood and monocytes from both groups. Intracellular levels of TNFalpha, IL-6 and IL-10 in monocytes are indistinguishable between HD patients and healthy controls. However, monocytes from HD patients are selectively primed for enhanced TNFalpha secretion in response to LPS. The selective inhibition of monocyte TNFalpha production by genistein may explain the anti-inflammatory action of this phytochemical observed in vivo.

Tissue-specific regulation of IL-6 production by IL-4. Differential effects of IL-4 on nuclear factor-kappa B activity in monocytes and fibroblasts.

IL-4 inhibits production of certain proinflammatory cytokines, including IL-1 beta, TNF-alpha, and IL-6, by activated monocytes. Although monocytes are a major source of IL-6, other cell types such as fibroblasts and endothelial cells can also express this cytokine. To determine whether IL-4 inhibits IL-6 expression in non-hemopoietic cells, we investigated the effects of IL-4 on IL-6 production in both primary human fibroblasts and fibroblast lines. Rheumatoid synovial fibroblasts were evaluated in these studies because, like monocytes, they produce high levels of IL-6 when stimulated with IL-1. Although peripheral blood monocytes did not constitutively express IL-6 mRNA or protein, stimulation with IL-1 or LPS induced de novo IL-6 expression in these cells. In contrast, synovial fibroblasts displayed a significant basal level of IL-6 production, which was markedly increased after stimulation with IL-1. IL-4 suppressed IL-6 expression in monocytes, but did not inhibit IL-6 production in synovial fibroblasts. The inability of IL-4 to suppress IL-6 synthesis in rheumatoid synovial fibroblasts was not caused by a lack of IL-4R and was not unique to these cells because IL-4 also failed to inhibit IL-6 production in normal fibroblast lines derived from other tissues. Inhibition of IL-6 production by IL-4 in monocytes was associated with decreased nuclear NF-kappa B levels. However, IL-4 does not globally suppress the activity of all DNA-binding proteins because IL-4 treatment did not reduce the levels of NF-IL-6 or NF-IL-1 beta B in the same cells. Because NF-kappa B activation is required for transcription of many cytokine genes, including IL-6, the ability of IL-4 to suppress NF-kappa B activity in monocytes suggests a potential mechanism by which this molecule may inhibit the expression of multiple cytokines.