A rapid host-protein test for differentiating bacterial from viral infection: Apollo diagnostic accuracy study.

Objectives: To determine the diagnostic accuracy of a rapid host-protein test for differentiating bacterial from viral infections in patients who presented to the emergency department (ED) or urgent care center (UCC). Methods: This was a prospective multicenter, blinded study. MeMed BV (MMBV), a test based on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon gamma-inducible protein-10 (IP-10), and C-reactive protein (CRP), was measured using a rapid measurement platform. Patients were enrolled from 9 EDs and 3 UCCs in the United States and Israel. Patients >3 months of age presenting with fever and clinical suspicion of acute infection were considered eligible. MMBV results were not provided to the treating clinician. MMBV results (bacterial/viral/equivocal) were compared against a reference standard method for classification of infection etiology determined by expert panel adjudication. Experts were blinded to MMBV results. They were provided with comprehensive patient data, including laboratory, microbiological, radiological and follow-up. Results: Of 563 adults and children enrolled, 476 comprised the study population (314 adults, 162 children). The predominant clinical syndrome was respiratory tract infection (60.5% upper, 11.3% lower). MMBV demonstrated sensitivity of 90.0% (95% confidence interval [CI]: 80.3-99.7), specificity of 92.8% (90.0%-95.5%), and negative predictive value of 98.8% (96.8%-99.6%) for bacterial infections. Only 7.2% of cases yielded equivocal MMBV scores. Area under the curve for MMBV was 0.95 (0.90-0.99). Conclusions: MMBV had a high sensitivity and specificity relative to reference standard for differentiating bacterial from viral infections. Future implementation of MMBV for patients with suspected acute infections could potentially aid with appropriate antibiotic decision-making.

Diagnostic Accuracy of a Real-Time Host-Protein Test for Infection.

OBJECTIVE: Determining infection etiology can be difficult because viral and bacterial diseases often manifest similarly. A host protein test that computationally integrates the circulating levels of TNF-related apoptosis-induced ligand, interferon γ-induced protein-10, and C-reactive protein to differentiate between bacterial and viral infection (called MMBV) demonstrated high performance in multiple prospective clinical validation studies. Here, MMBV's diagnostic accuracy is evaluated in febrile children for whom physicians were uncertain about etiology when applied at the physician's discretion. METHODS: Patients aged 3 months to 18 years were retrospectively recruited (NCT03075111; SPIRIT study; 2014-2017). Emergency department physician's etiological suspicion and certainty level were recorded in a questionnaire at blood-draw. MMBV results are based on predefined score thresholds: viral/non-bacterial etiology (0 ≤ score <35), equivocal (35 ≤ score ≤65), and bacterial or coinfection (65 < score ≤100). Reference standard etiology (bacterial/viral/indeterminate) was adjudicated by 3 independent experts based on all available patient data. Experts were blinded to MMBV. MMBV and physician's etiological suspicion were assessed against the reference standard. RESULTS: Of 3003 potentially eligible patients, the physicians were uncertain about infection etiology for 736 of the cases assigned a reference standard (128 bacterial, 608 viral). MMBV performed with sensitivity 89.7% (96/107; 95% confidence interval 82.4-94.3) and specificity 92.6% (498/538; 95% confidence interval 90.0-94.5), significantly outperforming physician's etiological suspicion (sensitivity 49/74 = 66.2%, specificity 265/368 = 72.0%; P < .0001). MMBV equivocal rate was 12.4% (91/736). CONCLUSIONS: MMBV was more accurate in determining etiology compared with physician's suspicion and had high sensitivity and specificity according to the reference standard.

An immune-protein score combining TRAIL, IP-10 and CRP for predicting severe COVID-19 disease.

COVID-19 patients are oftentimes over- or under-treated due to a deficit in predictive management tools. This study reports derivation of an algorithm that integrates the host levels of TRAIL, IP-10, and CRP into a single numeric score that is an early indicator of severe outcome for COVID-19 patients and can identify patients at-risk to deteriorate. 394 COVID-19 patients were eligible; 29% meeting a severe outcome (intensive care unit admission/non-invasive or invasive ventilation/death). The score's area under the receiver operating characteristic curve (AUC) was 0.86, superior to IL-6 (AUC 0.77; p = 0.033) and CRP (AUC 0.78; p < 0.001). Likelihood of severe outcome increased significantly (p < 0.001) with higher scores. The score differentiated severe patients who further deteriorated from those who improved (p = 0.004) and projected 14-day survival probabilities (p < 0.001). The score accurately predicted COVID-19 patients at-risk for severe outcome, and therefore has potential to facilitate timely care escalation and de-escalation and appropriate resource allocation.

BV score differentiates viral from bacterial-viral co-infection in adenovirus PCR positive children.

Background and objectives: Adenovirus causes acute respiratory illness that can mimic bacterial infection, making it challenging to differentiate adenoviral infection from adenoviral-bacterial co-infection. A host-protein score (BV score) for differentiating bacterial from viral infection that combines the expression levels of TNF-related apoptosis-induced ligand, interferon gamma-induced protein-10, and C-reactive protein exhibited a negative predictive value (NPV) of 98% in prior studies. Here we evaluate BV score's diagnostic accuracy in pediatrics with adenovirus PCR detection. Methods: This is a sub-analysis of children aged 3 months to 20 years with adenovirus PCR-positive infection recruited prospectively in two previous cohort studies. Reference standard diagnosis (bacterial, viral or indeterminate) was based on expert adjudication. BV score ranges from 0 to 100 and provides three results based on predefined cutoffs: viral or other non-bacterial etiology (0 ≤ score < 35), equivocal (35 ≤ score ≤ 65), and bacterial or co-infection (65 < score ≤ 100). Experts were blinded to BV results. Results: Out of 1,779 children, 142 had an adenovirus PCR-positive nasopharyngeal swab. Median age was 1.2 years (interquartile range 0.6-1.8), 50.7% were male and 52.8% were hospitalized. 12 cases were reference standard bacterial, 115 reference standard viral and 15 were indeterminate. BV score attained sensitivity of 100.0% (no false negatives), specificity of 89.5% (95% confidence interval: 83.2-95.8), and NPV of 100.0% (92.6-100.0). Equivocal rate was 19.7%. Conclusions: BV score accurately differentiated between adenoviral and bacterial-adenoviral co-infection in this cohort of children with PCR-positive adenovirus detection. This performance supports a potential to improve appropriate antibiotic use.

Correction to: The mTOR inhibitor rapamycin down-regulates the expression of the ubiquitin ligase subunit Skp2 in breast cancer cells.

After the publication of this work [1], an error was noticed in Fig. 2b, Fig. 3a and Fig. 5b. The Skp1 loading control was accidentally duplicated. We apologize for this error, which did not affect any of the interpretations or conclusions of the article.

Thrombin is a selective inducer of heparanase release from platelets and granulocytes via protease-activated receptor-1.

Heparanase, known to be involved in angiogenesis and metastasis, was shown to form a complex with tissue factor (TF) and to enhance the generation of factor Xa. Platelets and granulocytes contain abundant amounts of heparanase that may enhance the coagulation system upon discharge. It was the aim of this study to identify the inducer and pathway of heparanase release from these cells. Platelets and granulocytes were purified from pooled normal plasma and were incubated with ATP, ADP, epinephrine, collagen, ristocetin, arachidonic acid, serotonin, LPS and thrombin. Heparanase levels were assessed by ELISA, heparanase procoagulant activity assay and western blot analysis. The effects of selective protease-activated receptor (PAR)-1 and 2 inhibitors and PAR-1 and 4 activators were studied. An in-house synthesised inhibitory peptide to heparanase was used to evaluate platelet heparanase involvement in activation of the coagulation system. Heparanase was released from platelets only by thrombin induction while other inducers exerted no such effect. The heparanase level in a platelet was found to be 40 % higher than in a granulocyte. Heparanase released from platelets or granulocytes increased factor Xa generation by three-fold. PAR-1 activation via ERK intracellular pathway was found to induce heparanase release. In conclusion, heparanase is selectively released from platelets and granulocytes by thrombin interacting with PAR-1. Heparanase derived from platelets and granulocytes is involved in activation of the extrinsic coagulation pathway. The present study implies on a potential anticoagulant effect, in addition to anti-platelet effect, of the new clinically studied PAR-1 inhibitors.

Regulation of APC/C (Cdh1) ubiquitin ligase in differentiation of human embryonic stem cells.

We have recently shown that Skp2 levels are high in undifferentiated human embryonic stem cells, but decline rapidly following induction of differentiation, thereby leading to accumulation of p27. Changes in Skp2 levels were found to be caused mainly by its rate of degradation. Here we show that the activity of APC/C (Cdh1), the ubiquitin ligase that targets Skp2 for degradation, increases markedly during the differentiation process of human embryonic stem cells. APC/C (Cdh1) is present but inactive in undifferentiated embryonic stem cells and becomes active in the differentiated state. The rise in APC/C (Cdh1) activity with differentiation appears to be due, at least in part, to a dramatic decline in the levels of its inhibitor Emi1. In addition, protein kinase activity also appears to contribute to the suppression of APC/C (Cdh1) activity in undifferentiated stem cells, possibly by inhibitory phosphorylation of Cdh1.

Over-expression of Skp2 is associated with resistance to preoperative doxorubicin-based chemotherapy in primary breast cancer.

INTRODUCTION: Preoperative chemotherapy is often used in patients with locally advanced breast cancer. However, commonly used clinical and pathological parameters are poor predictors of response to this type of therapy. Recent studies have suggested that altered regulation of the cell cycle in cancer may be involved in resistance to chemotherapy. Over-expression of the ubiquitin ligase Skp2 results in loss of the cell cycle inhibitor p27Kip1 and is associated with poor prognosis in early breast cancer. The purpose of the present study was to examine the role of these proteins as predictors of clinical outcome and response to chemotherapy in locally advanced breast cancer. METHODS: The expression levels of Skp2 and p27Kip1 were determined by immunohistochemistry both before and after preoperative chemotherapy in 40 patients with locally advanced breast cancer. All patients were treated with cyclophosphamide/doxorubicin (adriamycin)/5-fluorouracil (CAF) and some patients received additional treatment with docetaxel. Expression data were compared with patients' clinical and pathological features, clinical outcome, and response to chemotherapy. RESULTS: Skp2 expression before preoperative chemotherapy was inversely related to p27Kip1 levels, tumor grade, and expression of estrogen and progesterone receptors. Both Skp2 and p27Kip1 were found to be accurate prognostic markers for disease-free and overall survival. High preoperative expression of Skp2 was associated with resistance to CAF therapy in 94% of patients (P < 0.0001) but not with resistance to docetaxel. CONCLUSION: Skp2 expression may be a useful marker for predicting response to doxorubicin-based preoperative chemotherapy and clinical outcome in patients with locally advanced breast cancer.

Agonist-specific down regulation of mu-opioid receptors: Different cellular pathways are activated by different opioid agonists.

Opioid agonists are known to induce down regulation of opioid receptors through the classical pathway that involves phosphorylation, clathrin-dependent endocytosis and lysosomal/endosomal degradation of the internalized receptors. As expected, exposure of mu-opioid receptor (MOR)-transfected HEK-293 cells to either DAMGO (a specific mu-opioid agonist) or etorphine (a wide spectrum opioid agonist) resulted in down regulation of the receptors that was blocked by the kinase inhibitor staurosporine, by hypertonic sucrose and by the lysosomal and proteasomal inhibitors chloroquine and lactacystin. High concentration of etorphine, but not of DAMGO, induced an additional process of down regulation that was resistant to staurosporine, to hypertonic sucrose and to chloroquine-lactacystin. Etorphine, but not DAMGO, also induced down regulation of mu-opioid receptors in isolated membranes of HEK cells. This membrane-delimited down regulation was blocked by selective inhibitors of protease enzymes, suggesting the involvement of membranous serine- and amino-peptidases. This membranous down regulation of opioid receptors was dependent on the concentration of etorphine and was blocked by the opioid antagonist naloxone. Etorphine induced similar down regulation in membranes of HEK-293 cells transfected with delta-opioid receptors (DOR) as well in membranes of cells that endogenously express opioid receptors. This agonist-specific membrane-delimited regulatory process appears to be physiologically relevant and should be taken into account when studying long term effects of opioid drugs.

Differential effects of doxorubicin treatment on cell cycle arrest and Skp2 expression in breast cancer cells.

Overexpression of Skp2, the ubiquitin ligase subunit that targets p27 for degradation, is often observed in cancers, and is associated with aggressive tumor proliferation and poor prognosis. As there is no drug at present that specifically targets Skp2, studies were undertaken to examine the effects of commonly used drugs on Skp2 regulation. Doxorubicin is among the most effective antitumor agents used for the management of breast cancer, but its effect on Skp2 expression is unknown. The objective of this study was to examine the effect of doxorubicin on Skp2 expression regulation in breast cancer cell lines. The expression of Skp2 mRNA and the protein levels of Skp2, p27, p21 and cyclin B were examined in doxorubicin-treated MCF-7 and MDA-MB-231 breast cancer cells. The effect of doxorubicin on the cell cycle profile was assessed by fluorescence-activated cell sorting analysis. Doxorubicin decreased Skp2 mRNA and protein levels in MCF-7 cells, but had the opposite effect in MDA-MB-231 cells. p27 levels were slightly decreased, whereas p53 and p21 levels were significantly upregulated in doxorubicin-treated MCF-7 cells. In contrast, p27 levels were unaffected by doxorubicin treatment in MDA-MB-231 cells, but cyclin B levels were markedly increased. Doxorubicin arrested MCF-7 cells at G1/S and G2/M checkpoints, whereas MDA-MB-231 cells were arrested at G2/M only. The differential effects of doxorubicin on Skp2 expression in breast cancer cells depend upon the specific cell cycle checkpoints activated by the drug. These changes induced by doxorubicin, however, do not significantly affect p27 expression in these cell lines, suggesting that the potential of a given drug to alter p27 expression through Skp2 modulation might depend on its specific action on cell cycle arrest.

Expression of the ubiquitin ligase subunit cyclin kinase subunit 1 and its relationship to S-phase kinase protein 2 and p27Kip1 in prostate cancer.

PURPOSE: Loss of the cell cycle inhibitory protein p27Kip1 in cancer is associated with tumor aggressiveness and poor prognosis in the prostate. The decrease in p27(Kip1) results from increased proteasome dependent degradation, which is mediated by its specific ubiquitin ligase subunits S-phase kinase protein 2 and cyclin dependent kinase subunit 1. S-phase kinase protein 2 was found to be over expressed in aggressive prostate cancers but to our knowledge the role of cyclin dependent kinase subunit 1 in these cancers is unknown. MATERIALS AND METHODS: The expression of cyclin dependent kinase subunit 1, S-phase kinase protein 2 and p27Kip1 was examined by immunohistochemistry in tissue sections from 45 patients with prostate cancer. The expression of cyclin dependent kinase subunit 1 was compared to that of S-phase kinase protein 2 and p27Kip1, and patient clinical and histological characteristics. RESULTS: Cyclin dependent kinase subunit 1 expression was strongly associated with S-phase kinase protein 2 expression (r = 0.666, p = 0.001) and inversely with p27Kip1 expression (r = -0.737, p < 0.001). Cyclin dependent kinase subunit 1 over expression was associated with loss of tumor differentiation (r = 0.631, p = 0.001), high serum prostate specific antigen (r = 0.627, p < 0.001) and metastatic disease (p < 0.001). CONCLUSIONS: These results suggest that cyclin dependent kinase subunit 1 is involved in p27Kip1 down-regulation and it may have an important causative role in the development of aggressive tumor behavior in prostate cancer.

The mTOR inhibitor rapamycin down-regulates the expression of the ubiquitin ligase subunit Skp2 in breast cancer cells.

INTRODUCTION: Loss of the cyclin-dependent kinase inhibitor p27 is associated with poor prognosis in breast cancer. The decrease in p27 levels is mainly the result of enhanced proteasome-dependent degradation mediated by its specific ubiquitin ligase subunit S phase kinase protein 2 (Skp2). The mammalian target of rapamycin (mTOR) is a downstream mediator in the phosphoinositol 3' kinase (PI3K)/Akt pathway that down-regulates p27 levels in breast cancer. Rapamycin was found to stabilize p27 levels in breast cancer, but whether this effect is mediated through changes in Skp2 expression is unknown. METHODS: The expression of Skp2 mRNA and protein levels were examined in rapamycin-treated breast cancer cell lines. The effect of rapamycin on the degradation rate of Skp2 expression was examined in cycloheximide-treated cells and in relationship to the anaphase promoting complex/Cdh1 (APC\C) inhibitor Emi1. RESULTS: Rapamycin significantly decreased Skp2 mRNA and protein levels in a dose and time-dependent fashion, depending on the sensitivity of the cell line to rapamycin. The decrease in Skp2 levels in the different cell lines was followed by cell growth arrest at G1. In addition, rapamycin enhanced the degradation rate of Skp2 and down-regulated the expression of the APC\C inhibitor Emi1. CONCLUSION: These results suggest that Skp2, an important oncogene in the development and progression of breast cancer, may be a novel target for rapamycin treatment.

Prognostic role of p27Kip1 deregulation in colorectal cancer.

p27Kip1, an inhibitor of cyclin-dependent kinases, is a negative cell cycle regulator that plays an important role in tumor suppression. Deregulation of p27 is commonly observed in many human cancers secondary to enhanced ubiquitin-mediated degradation, mediated and rate-limited by its specific ubiquitin ligase subunits Skp2 and Cks1. In the present study the prognostic implications of p27 and the mechanisms that down-regulate its expression in colorectal cancer (CRC) are reviewed. A review and analysis of the English literature was conducted. Loss of p27 was strongly associated with aggressive tumor behavior and poor clinical outcome in CRC. Overexpression of Skp2 and Cks1 was observed in aggressive CRC and is responsible for down-regulation of p27 levels. Both Skp2 and Cks1 were found to be independent prognostic markers for survival and provide predictive information additional to that provided by p27 alone. Deregulation of p27 has a profound effect on tumor progression in CRC and was found to be an accurate and independent prognostic marker. Thus, determination of levels of p27 and of its ubiquitin ligase subunits by readily available immunohistochemical studies may be a useful tool in the assessment of prognosis, especially in patients with intermediate disease, and may potentially assist in the planning of adjuvant therapy and development of novel interventional therapy.

The expression of the ubiquitin ligase subunit Cks1 in human breast cancer.

INTRODUCTION: Loss of the cell-cycle inhibitory protein p27Kip1 is associated with a poor prognosis in breast cancer. The decrease in the levels of this protein is the result of increased proteasome-dependent degradation, mediated and rate-limited by its specific ubiquitin ligase subunits S-phase kinase protein 2 (Skp2) and cyclin-dependent kinase subunit 1 (Cks1). Skp2 was recently found to be overexpressed in breast cancers, but the role of Cks1 in these cancers is unknown. The present study was undertaken to examine the role of Cks1 expression in breast cancer and its relation to p27Kip1 and Skp2 expression and to tumor aggressiveness. METHODS: The expressions of Cks1, Skp2, and p27Kip1 were examined immunohistochemically on formalin-fixed, paraffin-wax-embedded tissue sections from 50 patients with breast cancer and by immunoblot analysis on breast cancer cell lines. The relation between Cks1 levels and patients' clinical and histological parameters were examined by Cox regression and the Kaplan-Meier method. RESULTS: The expression of Cks1 was strongly associated with Skp2 expression (r = 0.477; P = 0.001) and inversely with p27Kip1 (r = -0.726; P < 0.0001). Overexpression of Cks1 was associated with loss of tumor differentiation, young age, lack of expression of estrogen receptors and of progesterone receptors, and decreased disease-free (P = 0.0007) and overall (P = 0.041) survival. In addition, Cks1 and Skp2 expression were increased by estradiol in estrogen-dependent cell lines but were down-regulated by tamoxifen. CONCLUSION: These results suggest that Cks1 is involved in p27Kip1 down-regulation and may have an important role in the development of aggressive tumor behavior in breast cancer.

The prognostic impact of the ubiquitin ligase subunits Skp2 and Cks1 in colorectal carcinoma.

BACKGROUND: Loss of the cell-cycle inhibitory protein p27Kip1 is associated with poor prognosis in colorectal carcinoma. The decrease in p27Kip1 levels is the result of increased proteasome-dependent degradation, mediated and rate-limited by its specific ubiquitin ligase subunits S-phase kinase protein (Skp) 2 and cyclin-dependent kinase subunit (Cks) 1. Recently, Skp2 and Cks1 expression were found to be increased in some colorectal carcinomas, but their potential role as prognostic markers for survival is unknown. The present study was undertaken to assess the prognostic value of both Skp2 and Cks1 in colorectal carcinoma. MATERIALS AND METHODS: The expression of Skp2, Cks1, and p27Kip1 was examined by immunohistochemistry using highly specific antibodies on formalin-fixed, paraffin-embedded tissue sections from 80 patients with colorectal carcinoma. RESULTS: Overexpression of Skp2 and Cks1 strongly correlated with loss of p27Kip1 and loss of tumor differentiation. A significant decrease in overall survival was observed in patients expressing high Skp2 or Cks1 levels, and in particular, patients with Stage II and III disease. Each protein provided significant additional prognostic information to that given by disease stage, tumor grade, or p27Kip1 expression. CONCLUSIONS: Results suggest that overexpression of Skp2 or Cks1 is strongly associated with poor prognosis and may thus be used as prognostic markers for overall survival in colorectal carcinoma.

Alterations in the expression of the cell cycle regulatory protein cyclin kinase subunit 1 in colorectal carcinoma.

BACKGROUND: Low levels of p27(Kip1) are associated with high aggressiveness and poor prognosis in various malignancies, including colorectal carcinoma. The authors showed that S phase kinase protein 2 (Skp2), the specific ubiquitin ligase subunit that targets p27(Kip1) for degradation, was overexpressed and was inversely related to p27(Kip1) levels in patients with colorectal carcinoma. The essential role of cyclin kinase subunit 1 (Cks1) in Skp2-dependent p27 degradation was recently discovered, but its role in human malignancies is unknown. METHODS: Quick-frozen colorectal tumor samples from 30 patients were separated by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, transferred to nitrocellulose, and probed with highly specific monoclonal antibodies directed against Cks1, Skp2, and p27(Kip1). The expression of Cks1 was also examined by immunohistochemistry using formalin-fixed, paraffin-embedded tissue sections from the same patients. RESULTS: A strong correlation was found between Cks1 levels and Skp2 expression and loss of tumor differentiation. A significant inverse relation was also observed between levels of Cks1 and p27(Kip1) and overall survival. CONCLUSIONS: The results of the current study suggest that increased expression of Cks1 may have an important causative role in decreasing levels of p27 in patients with aggressive colorectal carcinoma.

Long-term interactions between opioid and cannabinoid agonists at the cellular level: cross-desensitization and downregulation.

In the present study we investigated long-term interactions between opioid and cannabinoid drugs at several steps along their cellular signal transduction pathways. For this purpose we co-transfected HEK-293 and COS-7 cells with delta-opioid (DOR) and CB1-cannabinoid receptors, and examined the effect of prolonged exposure to either opioid (etorphine) or cannabinoid (DALN) agonists on DOR and CB-1 receptor density and on the ability of subsequent application of the agonists to activate G-proteins (as measured by [35S]GTPgammaS binding) and to inhibit cAMP production. In HEK-293 cells, etorphine induced both homologous and heterologous desensitization, while DALN induced only homologous desensitization. This asymmetric cross-desensitization coincided with asymmetric cross downregulation: etorphine downregulated the binding of the cannabinoid ligand [3H]CP55,940, while DALN failed to reduce the binding of the opioid ligand [3H]diprenorphine. In contrast to the asymmetric desensitization in HEK-293 cells, COS-7 cells presented a two-way cross-desensitization between opioid and cannabinoid agonists, and DALN downregulated the binding of [3H]diprenorphine in these cells. Thus, a complete correlation was found between downregulation and reduction in cell responsiveness ('desensitization'). Moreover, when opioid downregulation in HEK-293 cells was inhibited by either hypertonic sucrose solution or protein kinase inhibitors, desensitization was suppressed to the same extent. These results suggest that, under the present experimental conditions, the reduction in cell responsiveness resulted primarily from downregulation of the receptors.