Heteroarylketones inhibit astroglial interleukin-6 expression via a STAT3/NF-κB signaling pathway.

BACKGROUND: Elevated brain levels of the pleiotropic cytokine interleukin-6, which is mainly secreted from activated local astrocytes, contribute to pathological events including neuroinflammation and neurodegeneration. Thus, inhibition of pathological IL-6 expression provides a rationale strategy for targeting the onset or further progression of neurological disorders including Alzheimer's disease, multiple sclerosis, Parkinson's disease and traumatic brain injury. The purpose of this study was to identify and to characterize new potent inhibitors of astrocytic IL-6 expression for further therapeutic development of novel anti-inflammatory and neuroprotective drugs. METHODS: Oncostatin M (OSM)-treated human glioma U343 cells were used as model for induction of astrocytic IL-6 expression. This model was characterized by immunoblotting, siRNA technique, ELISA and qRT-PCR and used to screen low molecular weight compound libraries for IL-6-lowering effects. To validate bioactive compounds identified from library screens, bacterial lipopolysaccharide was used to induce IL-6 expression in cultivated primary astrocytes and in mice in vivo. To dissect underlying molecular mechanisms, protein extracts from OSM-treated U343 cells were analyzed by phospho-specific immunoblotting and immunocytochemistry as well as by co-immunoprecipitation. RESULTS: OSM-treatment (100 ng/ml; 24 h) led to 30-fold increase of IL-6 secretion from U343 cells. The temporal profile of IL-6 mRNA induction displayed a biphasic induction pattern with peak synthesis at 1 h (6.5-fold) and 16 h (5.5-fold) post stimulation. IL-6 protein release did not show that biphasic pattern and was detected as early as 3 h post stimulation reaching a maximum at 24 h. The screen of compound libraries identified a set of heteroarylketones (HAKs) as potent inhibitors of IL-6 secretion. HAK compounds affected the second peak in IL-6 mRNA synthesis, whereas the first peak was insensitive to HAK treatment. HAK compounds also suppressed lipopolysaccharide-induced IL-6 expression in primary murine astrocytes as well as in brain and plasma samples from lipopolysaccharide-treated mice. Finally, HAK compounds were demonstrated to specifically suppress the OSM-induced phosphorylation of STAT3 at serine 727 and the physical interaction of pSTAT3S727 with p65. CONCLUSION: Heteroarylketone compounds are potent inhibitors of IL-6 expression in vitro and in vivo and may represent a new class of potent anti-inflammatory and neuroprotective drugs.

The late phase of sepsis is characterized by an increased microbiological burden and death rate.

INTRODUCTION: Recent models capturing the pathophysiology of sepsis and ex-vivo data from patients are speculating about immunosuppression in the so-called late phase of sepsis. Clinical data regarding survival and microbiological burden are missing. The aim of this study was to determine the clinical significance of the 'late phase' of sepsis with respect to overall survival and occurrence of microbiological findings. METHODS: In a retrospective trial, 16,041 patient charts from a university intensive care unit were screened, and 999 patients with severe sepsis or septic shock were identified. Three phases were established according to the mortality peaks which were separated by two distinct nadirs: phase I (days 1 to 5), phase II (days 6 to 15) and phase III (days 16 to 150). Patients were analyzed for outcome, SOFA scores, procalcitonin levels, antimicrobial treatment, dialysis, mechanical ventilation and results of blood cultures during their hospital stay. RESULTS: Out of 999 enrolled patients, 308 died during the course of sepsis presenting a characteristic mortality rate (30.8%) with three distinct mortality peaks (at days 2, 7 and 17). Overall 36.7% of all deaths occurred in the early phase (phase I) and 63.3% during the later phases (phase II + III). In total 2,117 blood cultures were drawn. In phase I, 882 blood cultures were drawn, representing a sampling rate of 88% with a positive rate of 14.9%. In phase II, 461 samples were taken, indicating a sampling rate of 52% and a positive rate of 11.3%. Within phase III, 524 samples were obtained representing a sampling rate of 66% with a positive rate of 15.3%, which was significantly higher compared to the positive rate of phase II and similar to phase I. In particular, the rate of typically opportunistic bacteria increased significantly from 9% in phase I up to 18% in phase III. The same is true for Candida spp. (phase I 13%, phase III 30%). CONCLUSIONS: The later phase of sepsis is associated with a significant re-increase of positive blood culture results, especially regarding opportunistic bacteria and fungi. These observations warrant further studies focusing on the underlying mechanisms resulting in this outcome burden in the later phase of sepsis.

Dipeptidyl-Peptidase Activity of Meprin ß Links N-truncation of Aß with Glutaminyl Cyclase-Catalyzed pGlu-Aß Formation.

The formation of amyloid-ß (Aß) peptides is causally involved in the development of Alzheimer's disease (AD). A significant proportion of deposited Aß is N-terminally truncated and modified at the N-terminus by a pGlu-residue (pGlu-Aß). These forms show enhanced neurotoxicity compared to full-length Aß. Although the truncation may occur by aminopeptidases after formation of Aß, recently discovered processing pathways of amyloid-ß protein precursor (AßPP) by proteases such as meprin ß may also be involved. Here, we assessed a role of meprin ß in forming Aß3-40/42, which is the precursor of pGlu-Aß3-40/42 generated by glutaminyl cyclase (QC). Similar to QC, meprin ß mRNA is significantly upregulated in postmortem brain from AD patients. A histochemical analysis supports the presence of meprin ß in neurons and astrocytes in the vicinity of pGlu-Aß containing deposits. Cleavage of AßPP-derived peptides by meprin ß in vitro results in peptides Aß1-x, Aß2-x, and Aß3-x. The formation of N-truncated Aß by meprin ß was also corroborated in cell culture. A subset of the generated peptides was converted into pGlu-Aß3-40 by an addition of glutaminyl cyclase, supporting the preceding formation of Aß3-40. Further analysis of the meprin ß cleavage revealed a yet unknown dipeptidyl-peptidase-like activity specific for the N-terminus of Aß1-x. Thus, our data suggest that meprin ß contributes to the formation of N-truncated Aß by endopeptidase and exopeptidase activity to generate the substrate for QC-catalyzed pGlu-Aß formation.

Role of glutaminyl cyclases in thyroid carcinomas.

CCL2 is a chemokine known to recruit monocytes/macrophages to sites of inflammation. CCL2 is also associated with tumor progression in several cancer types. Recently, we showed that the N-terminus of CCL2 is modified to a pyroglutamate (pE)-residue by both glutaminyl cyclases (QC (QPCT)) and its isoenzyme (isoQC (QPCTL)). The pE-residue increases stability against N-terminal degradation by aminopeptidases. Here, we report an upregulation of QPCT expression in tissues of patients with thyroid carcinomas compared with goiter tissues, whereas QPCTL was not regulated. In thyroid carcinoma cell lines, QPCT gene expression correlates with the mRNA levels of its substrate CCL2. Both QPCT and CCL2 are regulated in a NF-κB-dependent pathway shown by stimulation with TNFa and IL1b as well as by inhibition with the IKK2 inhibitor and RNAi of p50. In the culture supernatant of thyroid carcinoma cells, equal amounts of pECCL2 and total CCL2 were detected by two ELISAs discriminating between total CCL2 and pECCL2, concluding that all CCL2 is secreted as pECCL2. Activation of the CCL2/CCR2 pathway by recombinant CCL2 increased tumor cell migration of FTC238 cells in scratch assays as well as thyroid carcinoma cell-derived CCL2-induced migration of monocytic THP1 cells. Suppression of CCL2 signaling by CCR2 antagonist, IKK2 inhibitor, and QPCT RNAi reduced FTC238 cell growth measured by WST8 proliferation assays. Our results reveal new evidence for a novel role of QC in thyroid carcinomas and provide an intriguing rationale for the use of QC inhibitors as a means of blocking pECCL2 formation and preventing thyroid cancer metastasis.

Potential effect of physiotherapeutic treatment on mortality rate in patients with severe sepsis and septic shock: a retrospective cohort analysis.

PURPOSE: The aim of the study was to examine the onset and frequency of physiotherapeutic interventions (PTI) and their potential effects on the intensive care unit (ICU) mortality rate in patients with severe sepsis or septic shock. MATERIAL AND METHODS: Retrospective data analysis. Univariate and multivariate Cox proportional-hazards regression analyses were performed. RESULTS: About 6.2% of all patients (n = 999, length of ICU stay 12 days, averaged SOFA score 14) developed sepsis within three years. Of these, 77% received at least once PTI. The relative number of PTI (RNPTI index, individually calculated by the number of PTI/length of stay) in patients with sepsis was 42%. The first physiotherapeutic treatment was five days after ICU admission. Cox regression multivariate analysis adjusted by disease severity scores, sedation state and other clinical variables found RNPTI index as significant risk factor for the ICU mortality rate (hazard ratio, 0.982; 95% confidence interval, 0.974-0.990; P < .001). CONCLUSIONS: Physiotherapists routinely assess and treat patients with sepsis. The frequency of PTI was associated with an improved outcome. Prospective studies are necessary to confirm the potential favorable impact.