The performance of metagenomic next-generation sequencing in diagnosing pulmonary infectious diseases using authentic clinical specimens: The Illumina platform versus the Beijing Genomics Institute platform.

Introduction: Metagenomic next-generation sequencing (mNGS) has been increasingly used to detect infectious organisms and is rapidly moving from research to clinical laboratories. Presently, mNGS platforms mainly include those from Illumina and the Beijing Genomics Institute (BGI). Previous studies have reported that various sequencing platforms have similar sensitivity in detecting the reference panel that mimics clinical specimens. However, whether the Illumina and BGI platforms provide the same diagnostic performance using authentic clinical samples remains unclear. Methods: In this prospective study, we compared the performance of the Illumina and BGI platforms in detecting pulmonary pathogens. Forty-six patients with suspected pulmonary infection were enrolled in the final analysis. All patients received bronchoscopy, and the specimens collected were sent for mNGS on the two different sequencing platforms. Results: The diagnostic sensitivity of the Illumina and BGI platforms was notably higher than that of conventional examination (76.9% vs. 38.5%, p < 0.001; 82.1% vs. 38.5%, p < 0.001; respectively). The sensitivity and specificity for pulmonary infection diagnosis were not significantly different between the Illumina and BGI platforms. Furthermore, the pathogenic detection rate of the two platforms were not significantly different. Conclusion: The Illumina and BGI platforms exhibited similar diagnostic performance for pulmonary infectious diseases using clinical specimens, and both are superior to conventional examinations.

Activation of the MAC1-ERK1/2-NOX2 Pathway Is Required for LPS-Induced Sustaining Reactive Microgliosis, Chronic Neuroinflammation and Neurodegeneration.

Recent studies suggest that improper resolution of acute neuroinflammation may lead to long-lasting low-grade chronic neuroinflammation and drive progressive neurodegeneration. However, the molecular mechanism underlying the transition from acute to chronic neuroinflammation remains unclear. The main purpose of this study was to search for potential pathways mediating LPS-elicited chronic neuroinflammation and resultant neurodegeneration. Using microglia cultures prepared from C57BL/6J, MAC1-deficient, and MyD88-deficient mice, the initial study showed that activation of TLR-4 is not sufficient for maintaining chronic neuroinflammation despite its essential role in LPS-initiated acute neuroinflammation. Opposite to TLR-4, our studies showed significantly reduced intensity of chronic neuroinflammation, oxidative stress, and progressive loss of nigral dopaminergic neurons in MAC1-deficient neuron/glial cultures or mice stimulated with LPS. Mechanistic studies revealed the essential role ERK1/2 activation in chronic neuroinflammation-elicited neurodegeneration, which was demonstrated by using an ERK1/2 inhibitor in neuron-glial cultures. Taken together, we propose a key role of the MAC1-NOX2-ERK1/2 signaling pathway in the initiation and maintenance of low-grade chronic neuroinflammation. Continuing ERK1/2 phosphorylation and NOX2 activation form a vicious feedforward cycle in microglia to maintain the low-grade neuroinflammation and drive neurodegeneration.

PEDF protects human retinal pigment epithelial cells against oxidative stress via upregulation of UCP2 expression.

To investigate the protective function of pigment epithelium­derived factor (PEDF) against oxidative stress (OS) in ARPE­19 cells, ARPE­19 cells were divided into different OS groups and treated with various concentrations of H2O2 (0, 75, 150 and 200 µmol/l) for 24 h. To establish the protective group, 200 ng/ml of PEDF was administered to ARPE­19 cells. Cell Counting Kit­8 assays and cell growth curve experiments were performed to determine levels of cell viability; lactate dehydrogenase and propidium iodide (PI) staining assays were also performed. The expression levels of genes associated with apoptosis as well as uncoupling protein 2 (UCP2) were detected by reverse transcription­quantitative, or semi­quantitative polymerase chain reaction. Furthermore, an OS injury animal model was established in both C57BL/6 and BALB/c mice via injection of 5 µg of PEDF in the vitreous cavity and subsequent injection of 150 µM H2O2 following a 24 h time interval. Hematoxylin and eosin (H&E) staining, as well as UCP2 immunofluorescent labeling were also performed. One­way analysis of variance was used to determine statistically significant differences, followed by multiple comparison analysis using the Newman Keuls method. The results of cell viability assays demonstrated that the numbers of apoptotic cells were increased following treatment with H2O2 in a dose­dependent manner; however, this effect was reversed following treatment with PEDF. The expression levels of caspase 3 and B cell lymphoma (Bcl2) associated X genes associated with apoptosis were inhibited, whereas levels of the anti­apoptotic gene Bcl2 were enhanced following treatment with PEDF in different passages of ARPE­19 cells. Significant differences were demonstrated in the levels of UCP2 gene expression between the PEDF+ H2O2 treated group and cells treated with H2O2 alone. Labeling of the UCP2 detector in the confocal images demonstrated decreased UCP2 protein staining in the retinal pigment epithelium (RPE) cells and RPE layers following H2O2 injury; however, this effect was inhibited following treatment with PEDF. H&E staining was performed to investigate the thickness of the RPE layers, and the results revealed that thicknesses were significantly increased in sections treated with PEDF during OS, due to increased numbers of RPE cells. Furthermore, PEDF was demonstrated to increase UCP2 gene expression in ARPE­19 cells and animal RPE layers under OS, which suggested that PEDF may protect RPE cells and tissues during oxidative injury.

[Diagnostic value of serum procalcitonin in urinary tract infection].

OBJECTIVE: To analyze the serum level of procalcitonin (PCT) in urinary tract infection (UTI) patients with urinary obstruction or bacteremia, and to investigate the value of PCT in diagnosing UTI. METHODS: A total of 102 patients with UTI hospitalized from January to December 2013 in the Second Hospital of Tianjin Medical University were categorized into obstructed UTI (n=60) and non-obstructed UTI (n=42), whose serum PCT concentrations were compared. Blood cultures were implemented in 44 patients, including 13 with positive findings (bacteremia) and 31 with negative findings (non-bacteremia). Serum PCT levels were also compared between the bacteremia and non-bacteremia groups. Receiver operating characteristic (ROC) curves were constructed to illustrate the performance of PCT in diagnosing urinary obstruction and bacteremia. RESULTS: The median serum concentration of PCT in the obstructed UTI group (1.71 (0.10-53.20) mg/L)was higher than that in the non-obstructed UTI group (0.21 (0.10-10.00) mg/L, P<0.001); the serum concentration of PCT in the bacteremia group (2.73 (0.10-41.60) mg/L) was higher than that in the non-bacteremia group (0.42 (0.10-53.20) mg/L, P=0.030). The area under ROC curve of PCT in diagnosing urinary obstruction and bacteremia was 0.80 (95% CI 0.71-0.89) and 0.71 (95% CI 0.53-0.88). The maximum negative predictive value (NPV) was 0.90 and 0.87, respectively, when the serum concentrations of PCT diagnosing bacteremia and urinary obstruction was 0.51 mg/L and 0.35 mg/L. CONCLUSION: PCT may be of some value in diagnosing UTI with urinary obstruction or bacteremia.