Highlights RT-ddPCR is more sensitive to inhibitors than RT-qPCR for primary clarified sludge Primary clarified sludge has elevated frequency of SARS-CoV-2 RNA detection Primary clarified sludge allows detection of RNA during low COVID-19 incidence PMMV normalization of RNA data reduces noise and increases precision PMMV normalization of RNA shows strongest correlation to epidemiological metrics

Alterations in gut microbiota have been implicated in the pathogenesis of inflammatory bowel disease (IBD), however factors that mediate the host–microbiota interactions remain largely unknown. Here we collected mucosal-luminal interface samples from a pediatric IBD inception cohort and characterized both the human and microbiota proteins using metaproteomics. We show that microbial proteins related to oxidative stress responses are upregulated in IBD cases compared to controls. In particular, we demonstrate that the expression of human proteins related to oxidative antimicrobial activities is increased in IBD cases and correlates with the alteration of microbial functions. Additionally, we reveal that many of these human proteins are present and show altered abundance in isolated free extracellular vesicles (EVs). Therefore, our study suggests that the alteration of intestinal EV proteomes is associated with the aberrant host–microbiota interactions in IBD.

BackgroundThe gut microbiota has been shown to be closely associated with human health and disease. While next-generation sequencing can be readily used to profile the microbiota taxonomy and metabolic potential, metaproteomics is better suited for deciphering microbial biological activities. However, the application of gut metaproteomics has largely been limited due to the low efficiency of protein identification. Thus, a high-performance and easy-to-implement gut metaproteomic approach is required.ResultsIn this study, we developed a high-performance and universal workflow for gut metaproteome identification and quantification (named MetaPro-IQ) by using the close-to-complete human or mouse gut microbial gene catalog as database and an iterative database search strategy. An average of 38 and 33 % of the acquired tandem mass spectrometry (MS) spectra was confidently identified for the studied mouse stool and human mucosal-luminal interface samples, respectively. In total, we accurately quantified 30,749 protein groups for the mouse metaproteome and 19,011 protein groups for the human metaproteome. Moreover, the MetaPro-IQ approach enabled comparable identifications with the matched metagenome database search strategy that is widely used but needs prior metagenomic sequencing. The response of gut microbiota to high-fat diet in mice was then assessed, which showed distinct metaproteome patterns for high-fat-fed mice and identified 849 proteins as significant responders to high-fat feeding in comparison to low-fat feeding.ConclusionsWe present MetaPro-IQ, a metaproteomic approach for highly efficient intestinal microbial protein identification and quantification, which functions as a universal workflow for metaproteomic studies, and will thus facilitate the application of metaproteomics for better understanding the functions of gut microbiota in health and disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-016-0176-z) contains supplementary material, which is available to authorized users.

The discovery of autosomal dominant hypercholesterolemic patients with mutations in the PCSK9 gene, encoding the proprotein convertase NARC-1, resulting in the missense mutations suggested a role in low density lipoprotein (LDL) metabolism. We show that the endoplasmic reticulum-localized proNARC-1 to NARC-1 zymogen conversion is Ca 2؉ -independent and that within the zymogen autocatalytic processing site SSVFAQ2SIP Val at P4 and Pro at P3 are critical. The S127R and D374Y mutations result in ϳ50 -60% and >98% decrease in zymogen processing, respectively. In contrast, the double [D374Y ؉ N157K], F216L, and R218S natural mutants resulted in normal zymogen processing. The cell surface LDL receptor (LDLR) levels are reduced by 35% in lymphoblasts of S127R patients. The LDLR levels are also reduced in stable HepG2 cells overexpressing NARC-1 or its natural mutant S127R, and this reduction is abrogated in the presence of 5 mM ammonium chloride, suggesting that overexpression of NARC-1 increases the turnover rate of the LDLR. Adenoviral expression of wild type human NARC-1 in mice resulted in a maximal ϳ9-fold increase in circulating LDL cholesterol, while in LDLR(؊/؊) mice a delayed ϳ2-fold increase in LDL cholesterol was observed. In conclusion, NARC-1 seems to affect both the level of LDLR and that of circulating apoB-containing lipoproteins in an LDLR-dependent and -independent fashion.The mammalian proprotein convertases constitute a family of 9 serine proteinases related to bacterial subtilisin. These include the 7 basic amino acid-specific convertases known as PC1/PC3, PC2, furin, PC4, PACE4, PC5/PC6, PC7/LPS (1, 2) and the two enzymes cleaving at nonbasic residues SKI-1/S1P (3, 4) and NARC-1/PCSK9 (5). These proteases are implicated in the limited proteolysis of precursors of secretory proteins that regulate a variety of cellular functions, including cellular growth, adhesion, differentiation, cell to cell communications, and endocrine/paracrine functions (6, 7). Published gene knockout analyses (reviewed in Ref. 8) revealed that only furin (9) and SKI-1/S1P (10) are embryonic lethal. So far, nothing is known about the phenotype consequences of NARC-1 1 knockout in mice. The cDNA of the enzyme NARC-1 was cloned during pharmaceutical screening of mRNAs up-regulated following induction of neural apoptosis by serum withdrawal, and the encoded protein was called "neural apoptosis regulated convertase 1" (NARC-1) (11). We characterized this enzyme, and we showed that it is highly expressed in liver and small intestine and that specific mutations in the prosegment of NARC-1 completely abrogated its autocatalytic processing (5). We further showed that overexpression of NARC-1 enhances neurogenesis of progenitor brain telencephalic cells. The sustained expression of NARC-1 in liver and small intestine and its transient expression in telencephalon, kidney, and cerebellum beg for the identification of its physiological substrates, which are still unknown.Human genetic point mutations resulting in pathology have been rep...

In the absence of an effective vaccine to prevent COVID-19 it is important to be able to track community infections to inform public health interventions aimed at reducing the spread and therefore reduce pressures on health-care units, improve health outcomes and reduce economic uncertainty. Wastewater surveillance has rapidly emerged as a potential tool to effectively monitor community infections for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), through measuring trends of viral RNA signal in wastewater systems. In this study SARS-CoV-2 viral RNA N1 and N2 genes are quantified in solids collected from influent post grit solids (PGS) and primary clarified sludge (PCS) in two water resource recovery facilities (WRRF) serving Canada's national capital region, i.e., the City of Ottawa, ON (pop. = 1.1M) and the City of Gatineau, QC (pop. = 280K). PCS samples show signal inhibition using RT-ddPCR compared to RT-qPCR, with PGS samples showing similar quantifiable concentrations of RNA using both assays. RT-qPCR shows higher frequency of detection of N1 and N2 genes in PCS (92.7, 90.6%) as compared to PGS samples (79.2, 82.3%). Sampling of PCS may therefore be an effective approach for SARS-CoV-2 viral quantification, especially during periods of declining and low COVID-19 incidence in the community. The pepper mild mottle virus (PMMV) is determined to have a less variable RNA signal in PCS over a three month period for two WRRFs, regardless of environmental conditions, compared to Bacteroides 16S rRNA or human eukaryotic 18S rRNA, making PMMV a potentially useful biomarker for normalization of SARS-CoV-2 signal. PMMV-normalized PCS RNA signal from WRRFs of two cities correlated with the regional public health epidemiological metrics, identifying PCS normalized to a fecal indicator (PMMV) as a potentially effective tool for monitoring trends during decreasing and low-incidence of infection of SARS-Cov-2 in communities.