Microbiome-metabolomics analysis of the effects of decreasing dietary crude protein content on goat rumen mictobiota and metabolites.

OBJECTIVE: The objective of this study was to investigate the effects of decreasing dietary crude protein content on rumen fermentation, mictobiota, and metabolites in goats. METHODS: In an 84-day feeding trial, a total of twelve male Anhui white goat kids with initial body weight 15.9±1.13 kg were selected and randomly classified into two groups, feeding a normal crude protein diet (14.8% CP, NCP) or a low crude protein diet (12.0% CP, LCP). At the end of the experimental trial (on day 84), six animals were randomly selected from each group and were slaughtered to collect rumen fluid samples for the analysis of rumen fermentation parameters, microbiome, and metabolome. RESULTS: The concentrations of ammonia-nitrogen, total volatile fatty acid, acetate, and propionate were decreased (p<0.05) in the LCP group in comparison with those in the NCP group. The abundances of genera Prevotella, Campylobacter, Synergistetes, and TG5, which were associated with nitrogen metabolism, were lower (p<0.05) in the LCP group compared with those in the NCP group. The levels of 78 metabolites (74 decreased, 4 increased) in the rumen fluid were altered (p<0.05) by the treatment. Most of the ruminal metabolites that showed decreased levels in the LCP group were substrates for microbial protein synthesis. Metabolic pathway analysis showed that vitamin B6 metabolism was significantly different (p<0.05) in rumen fluid between the two treatments. CONCLUSION: Decreased dietary protein level inhibited rumen fermentation through microbiome and metabolome shifts in goat kids. These results enhance our understanding of ruminal bacteria and metabolites of goat fed a low protein diet.

Inhibition of the immunoproteasome LMP2 ameliorates ischemia/hypoxia-induced blood-brain barrier injury through the Wnt/ß-catenin signalling pathway.

BACKGROUND: Disruption of the blood-brain barrier (BBB) after a stroke can lead to brain injury and neurological impairment. Previous work confirmed the involvement of the immunoproteasome subunit of low molecular mass peptide 2 (LMP2) in the pathophysiology of ischemia stroke. However, the relationship between the immunoproteasome LMP2 and the BBB remains unclear. METHODS: Adult male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion/reperfusion (MCAO/R). Three days before MCAO, the rats were treated with lentivirus-mediated LMP2 shRNA preparations by stereotactical injection into the ipsilateral hemispheric region. The rat brain microvascular endothelial cell (RBMVEC) line was exposed to oxygen-glucose deprivation/reperfusion (OGD/R) to mimic ischemic conditions in vitro. The RNA interference-mediated knockdown of LMP2 or ß-catenin was analysed in vivo and in vitro. Analysis of the quantity of extravasated Evans blue (EB) and cerebral fluorescent angiography were performed to evaluate the integrity of the BBB. Immunofluorescence and Western blotting were employed to detect the expression of target proteins. Cell migration was evaluated using a scratch migration assay. The results of immunofluorescence, Western blotting and cell migration were quantified using the software ImageJ (Version 1.53m). Parametric data from different groups were compared using one-way ANOVA followed by the least significant difference (LSD) test. RESULTS: Cerebral ischemia led to lower levels of structural components of the BBB such as tight junction proteins (occludin, claudin-1 and ZO-1) in the MCAO/R group compared with the sham group (P < 0.001). However, inhibition of the immunoproteasome LMP2 restored the expression of these proteins, resulting in higher levels of occludin, claudin-1 and ZO-1 in the LMP2-shRNA group compared with the control-shRNA group (P < 0.001). In addition, inhibition of the immunoproteasome LMP2 contributed to higher microvascular density and decreased BBB permeability [e.g., the quantity of extravasated EB: LMP2-shRNA group (58.54 ± 7.37) µg/g vs. control-shRNA group (103.74 ± 4.32) µg/g, P < 0.001], and promoted the upregulation of Wnt-3a and ß-catenin proteins in rats following MCAO/R. In vitro experiments, OGD/R induced marked upregulation of LMP2, proapoptotic protein Bax and cleaved caspase-3, and downregulation of occludin, claudin-1, ZO-1 and Bcl-2, as well as inhibition of the Wnt/ß-catenin pathway Wnt-3a and ß-catenin proteins in RBMVECs, compared with the control group under normal culture conditions (P < 0.001). However, silencing of LMP2 gene expression reversed these protein changes and promoted proliferation and migration of RBMVECs following OGD/R. Silencing of ß-catenin by transfection of RBMVECs with ß-catenin-siRNA aggravated the downregulation of tight junction proteins, and reduced the proliferation and migration of RBMVECs following OGD/R, compared with the control-siRNA group (P < 0.001). LMP2-siRNA and ß-catenin-siRNA co-transfection partly counteracted the beneficial effects of silencing LMP2-siRNA on the levels of tight junction proteins in RBMVECs exposed to OGD/R. CONCLUSION: This study suggests that inhibition of the immunoproteasome LMP2 ameliorates ischemia/hypoxia-induced BBB injury, and that the molecular mechanism involves the immunoproteasome-regulated activation of the Wnt/ß-catenin signalling pathway under ischemic conditions.

Association between plasma immunoproteasome and 90-day prognosis after first-ever ischemic stroke.

Many blood biomarkers are reportedly helpful for predicting post-stroke cognitive impairment (PSCI), but no biomarkers are widely used in clinical practice. The purpose of this study was to investigate the association between the plasma immunoproteasome and patients' 90-day prognosis after first-ever acute ischemic stroke. In our prospective, single-center study, 259 patients with first-ever acute ischemic stroke were enrolled from the Department of Neurology, Fujian Provincial Hospital, China, from March to September 2014. Of these, 27 patients (10.4%) had unfavorable outcomes as assessed by the Modified Rankin Scale (scores of 3-6). The National Institutes of Health Stroke Scale score on admission, plasma N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) levels, and immunopro-teasome subunit (low molecular mass peptide [LMP]2, LMP5, and LMP7) levels were significantly higher in the unfavorable outcome group than in the favorable outcome group. To predict unfavorable outcomes, the optimal cutoff points were National Institutes of Health Stroke Scale score > 12, NT-pro-BNP level > 1883.5 pg/mL, and LMP2 level > 841.4 pg/mL. Of the 193 patients that were able to complete the Mini-Mental State Examination at 90 days post-stroke, 66 patients (34.2%) had PSCI. Plasma levels of NT-pro-BNP and LMP2 were higher in patients with PSCI than in those without PSCI. To predict PSCI, the optimal cutoff values were age > 70.5 years and LMP2 level > 630.5 pg/mL. These findings indicate that plasma LMP2 may serve as a new prognostic biomarker of poor outcome and PSCI at 90 days after stroke. This study was approved by the Ethics Committee of Fujian Provincial Hospital, Provincial Clinical Medical College of Fujian Medical University (approval No. K2014-01-003) on January 15, 2014.

Involvement of p38 and c-Jun N-terminal protein kinase in cardiotoxin III-induced apoptosis of K562 cells.

Cardiotoxin III (CTX III), a 60-amino acid basic polypeptide isolated from Naja venom, showed potential therapeutic activity toward cancer cells. Here we report that CTX III inhibited proliferation of human leukemia K562 cells by G2/M phase arresting and apoptosis which was associated with the activation of caspase-8 and cytochrome c release as well as the p38 and c-Jun N-terminal protein kinase (JNK) phosphorylation signaling pathway. We further demonstrated that daily administration of CTX III for 2 d to chicken chorioallantoic membrane (CAM) bearing tumours derived from the CAM at E10 administration of K562 cells resulted in inhibition of the tumours in vivo. Importantly, this in vivo inhibition was also associated with caspase-8 activation and cytochrome c release. Our results suggest that CTX III-induced apoptosis is mediated via the p38 and JNK pathway as well as the caspase-8-dependent Bid-Bax pathway in human K562 cells.