Simple lateral flow assays for microbial detection in stool

Diarrheal diseases claim the lives of 1300 children daily, mostly in the developing world. We have developed a simple lateral flow assay capable of detecting E. coli and EPEC DNA and RNA rapidly (<15 minutes) at the point-of-need, directly from stool without nucleic acid extraction or molecular amplification. The limit of detection of the method is 1 nM using synthetic DNA target substrates spiked into stool. However, due to the endogenous amplification of the 23S rRNA targets, we were able to detect the endogenous EPEC in pea-sized (5 mg) stool without labor-intensive and time-consuming nucleic acid purification or target amplification using enzymes. The significance of this method is that it is rapid (<15 minutes) and simple (without nucleic acid purification or molecular amplification) and does not require instrumentation, or access to a laboratory, cold chain or electric power. Thus, it is well-suited for point-of-need use in remote and/or resource-limited settings in the developing world where the mortality due to diarrheal diseases is especially high. The rapid testing of stool pathogens in real time at the point-of-need will decrease the loss of patients to follow-up, and enable patients to be treated earlier with the appropriate therapeutics in both the developed and developing world settings.

Data supporting the effects of lysozyme on mRNA and protein expression in a colonic epithelial scratch wound model

Colonic epithelial health is implicated in a host of gastrointestinal (GI) diseases and disorders. Lysozyme is suspected to play a role in the ability of the epithelium to recover from injury (Abey et al., in press; Gallo, 2012; Rubio, 2014) [1], [2], [3]. Disrupted repair mechanisms may lead to delayed or ineffective recovery and disruptions to epithelial biology resulting in GI symptoms and altered barrier function (Peterson and Artis, 2014) [4]. The effect of lysozyme on the transcriptomic and proteomic profile of healthy colonic epithelial cells was investigated. Epithelial cells in culture were scratch wounded and treated with lysozyme. mRNA and protein profiles were simultaneously quantified in the same sample using a digital counting technology. Gene and protein expressions altered by the presence or absence of lysozyme are described in this article. Extensive statistical and bioinformatic analysis, and interpretation of the results can be found in "Lysozyme association with circulating RNA, extracellular vesicles, and chronic stress" (Abey et al., in press) [1].

Lysozyme association with circulating RNA, extracellular vesicles, and chronic stress

BACKGROUND

Stress has demonstrated effects on inflammation though underlying cell-cell communication mechanisms remain unclear. We hypothesize that circulating RNAs and extracellular vesicles (EVs) in patients with chronic stress contain signals with functional roles in cell repair.

METHODS

Blood transcriptome from patients with Irritable Bowel Syndrome versus controls were compared to identify signaling pathways and effectors. Plasma EVs were isolated (size-exclusion chromatography) and characterized for effectors' presence (immunogold labelling-electron microscopy). Based on transcriptome pathways and EV-labelling, lysozyme's effects on cell migration were tested in human colon epithelial CRL-1790 cells and compared to the effects of CXCL12, a migration inducer (wound assay). The effect of lysozyme on immune-linked mRNA and protein levels in cells which survived following serum starvation and scratch wound were investigated (NanoString).

RESULTS

Blood transcriptomes revealed pyridoxal 5'phosphate salvage, pyrimidine ribonucleotides salvage pathways, atherosclerosis, and cell movement signaling with membrane CD9 and extracellular lysozyme as effectors. Plasma EVs showed labelling with CD9, mucins, and lysozyme. This is the first identification of lysozyme on plasma EVs. In CRL-1790 cells, lysozyme induced migration and repaired scratch wound as well as CXCL12. Immune mRNA and protein expressions were altered in cells which survived following serum starvation and scratch wound, with or without lysozyme in serum-free media post-wounding: CD9, IL8, IL6 mRNAs and CD9, NT5E, PD-L1 proteins.

CONCLUSIONS

Repair and inflammatory signals are identified in plasma EVs and circulating RNAs in chronic stress. Registered clinicaltrials.gov #NCT00824941.

GENERAL SIGNIFICANCE

This study highlights the role of circulating RNAs and EVs in stress.