Early application of metagenomics next-generation sequencing may significantly reduce unnecessary consumption of antibiotics in patients with fever of unknown origin.

BACKGROUND: Metagenomic next-generation sequencing (mNGS) is a novel nucleic acid method for the detection of unknown and difficult pathogenic microorganisms, and its application in the etiological diagnosis of fever of unknown origin (FUO) is less reported. We aimed to comprehensively assess the value of mNGS in the etiologic diagnosis of FUO by the pathogen spectrum and diagnostic performance, and to investigate whether it is different in the time to diagnosis, length of hospitalization, antibiotic consumption and cost between FUO patients with and without early application of mNGS. METHODS: A total of 149 FUO inpatients underwent both mNGS and routine pathogen detection was retrospectively analyzed. The diagnostic performance of mNGS, culture and CMTs for the final clinical diagnosis was evaluated by using sensitivity, specificity, positive predictive value, negative predictive value and total conforming rate. Patients were furtherly divided into two groups: the earlier mNGS detection group (sampling time: 0 to 3 days of the admission) and the later mNGS detection group (sampling time: after 3 days of the admission). The length of hospital stay, time spent on diagnosis, cost and consumption of antibiotics were compared between the two groups. RESULTS: Compared with the conventional microbiological methods, mNGS detected much more species and had the higher negative predictive (67.6%) and total conforming rate (65.1%). Patients with mNGS sampled earlier had a significantly shorter time to diagnosis (6.05+/-6.23 vs. 10.5+/-6.4 days, P < 0.001) and days of hospital stay (13.7+/-20.0 vs. 30.3 +/-26.9, P < 0.001), as well as a significantly less consumption (13.3+/-7.8 vs. 19.5+/-8.0, P < 0.001) and cost (4543+/-7326 vs. 9873 +/- 9958 China Yuan [CNY], P = 0.001) of antibiotics compared with the patients sampled later. CONCLUSIONS: mNGS could significantly improve the detected pathogen spectrum, clinical conforming rate of pathogens while having good negative predictive value for ruling out infections. Early mNGS detection may shorten the diagnosis time and hospitalization days and reduce unnecessary consumption of antibiotics.

The adhesion and migration of microglia to ß-amyloid (Aß) is decreased with aging and inhibited by Nogo/NgR pathway.

BACKGROUND: Alzheimer's disease is characterized by progressive accumulation of ß-amyloid (Aß)-containing amyloid plaques, and microglia play a critical role in internalization and degradation of Aß. Our previous research confirmed that Nogo-66 binding to Nogo receptors (NgR) expressed on microglia inhibits cell adhesion and migration in vitro. METHODS: The adhesion and migration of microglia isolated from WT and APP/PS1 mice from different ages were measured by adhesion assays and transwells. After NEP1-40 (a competitive antagonist of Nogo/NgR pathway) was intracerebroventricularly administered via mini-osmotic pumps for 2 months in APP/PS1 transgenic mice, microglial recruitment toward Aß deposits and CD36 expression were determined. RESULTS: In this paper, we found that aging led to a reduction of microglia adhesion and migration to fAß1-42 in WT and APP/PS1 mice. The adhesion and migration of microglia to fAß1-42 were downregulated by the Nogo, which was mediated by NgR, and the increased inhibitory effects of the Nogo could be observed in aged mice. Moreover, Rho GTPases contributed to the effects of the Nogo on adhesion and migration of microglia to fAß1-42 by regulating cytoskeleton arrangement. Furthermore, blocking the Nogo/NgR pathway enhanced recruitment of microglia toward Aß deposits and expression of CD36 in APP/PS1 mice. CONCLUSION: Taken together, Nogo/NgR pathway could take part in Aß pathology in AD by modulating microglial adhesion and migration to Aß and the Nogo/NgR pathway might be an important target for treating AD.

The Nogo/Nogo Receptor (NgR) Signal Is Involved in Neuroinflammation through the Regulation of Microglial Inflammatory Activation.

Microglia have been proposed to play a pivotal role in the inflammation response of the CNS by expressing a range of proinflammatory enzymes and cytokines under pathological stimulus. Our previous study has confirmed that Nogo receptor (NgR), an axon outgrowth inhibition receptor, is also expressed on microglia and regulates cell adhesion and migration behavior in vitro. In the present study, we further investigated the proinflammatory effects and possible mechanisms of Nogo on microglia in vitro. In this study, Nogo peptide, Nogo-P4, a 25-amino acid core inhibitory peptide sequence of Nogo-66, was used. We found that Nogo-P4 was able to induce the expression of inducible nitric-oxide synthase and cyclooxygenase-2 and the release of proinflammatory cytokines, including IL-1ß, TNF-α, NO, and prostaglandin E2 in microglia, which could be reversed by NEP1-40 (Nogo-66(1-40) antagonist peptide), phosphatidylinositol-specificphospholipase C, or NgR siRNA treatment. After Nogo-P4 stimulated microglia, the phosphorylation levels of NF-κB and STAT3 were increased obviously, which further mediated microglia expressing proinflammatory factors induced by Nogo-P4. Taken together, we concluded that Nogo peptide could directly take part in CNS inflammatory process by influencing the expression of proinflammatory factors in microglia, which were related to the NF-κB and STAT3 signal pathways. Besides neurite outgrowth restriction, the Nogo/NgR signal might be involved in multiple processes in various inflammation-associated CNS diseases.

The blockage of the Nogo/NgR signal pathway in microglia alleviates the formation of Aß plaques and tau phosphorylation in APP/PS1 transgenic mice.

BACKGROUND: Alzheimer's disease (AD) is characterized by extracellular ß-amyloid (Aß) plaques, neurofibrillary tangles (NFTs), and microglia-dominated neuroinflammation. The Nogo/NgR signal pathway is involved in AD pathological features, but the detailed mechanism needs further investigation. Our previous studies have confirmed that the activation of NgR on microglia by Nogo promotes the expression of proinflammatory cytokines and inhibits cell adhesion and migration behaviors. In the present study, we investigated the effects of Nogo/NgR signaling pathway on the pathological features of AD and possible mechanisms. METHODS: After NEP1-40 (a competitive antagonist of Nogo/NgR pathway) was intracerebroventricularly administered via mini-osmotic pumps for 2 months in amyloid precursor protein (APP)/PS1 transgenic mice, plaque load, tau phosphorylation, and inflammatory responses were determined. After primary mouse neurons were exposed to the conditioned medium from BV-2 microglia stimulated by Nogo, the production of Aß and phosphorylation of tau was quantified by ELISA and western blot. RESULTS: Inhibition of the Nogo/NgR signaling pathway ameliorated pathological features including amyloid plaques and phosphorylated levels of tau in APP/PS1 mice. In addition, after treatment with the conditioned medium from BV-2 microglia stimulated by Nogo, Aß production and tau phosphorylation in cultured neurons were increased. The conditioned medium also increased the expression of APP, its amyloidogenic processing, and the activity of GSK3ß in neurons. The conditioned medium was also proinflammatory medium, and the blockage of the Nogo/NgR pathway improved the neuroinflammatory environment in APP/PS1 mice. CONCLUSIONS: Taken together, the neuroinflammation mediated by Nogo/NgR pathway in microglia could directly take part in the pathological process of AD by influencing the amyloidogenesis and tau phosphorylation. These results contribute to a better understanding of AD pathogenesis and could offer a new therapeutic option for delaying the progression of AD.

Quercetin promotes motor and sensory function recovery following sciatic nerve-crush injury in C57BL/6J mice.

Injuries and diseases that occur in the nervous system are common and have few effective treatments. Previous studies have shown that quercetin has a therapeutic effect on nervous system injuries, but its potential effects on and mechanisms of action related to behavioral recovery and axonal regrowth have not been investigated. Here, we showed that quercetin administration promotes behavioral recovery following sciatic nerve-crush injury in mice. Long-term evaluation showed that mice administered 20 mg·kg-1·day-1 quercetin for 35 days had a greater sensorimotor recovery compared with all other treatment groups. The mechanisms behind these effects were further investigated, and quercetin was found to regulate the expression of genes involved in regeneration and trophic support. Moreover, quercetin increased cyclic adenosine monophosphate expression and downstream pathway activation, which directly leads to neuronal growth activation in peripheral axon regeneration. In addition, quercetin enhanced axon remyelination, motor nerve conduction velocity and plantar muscle function, indicating that the degree of distal portion hypotrophy during the peripheral axon regeneration process was reduced. These results suggest that quercetin accelerates functional recovery by up-regulating neuronal intrinsic growth capacity and postponing distal atrophy. Overall, quercetin triggered multiple effects to promote behavioral recovery following sciatic nerve-crush injury in mice.