Whole-genome sequencing for rapid, reliable and routine investigation of Mycobacterium tuberculosis transmission in local communities.

Contact investigations following the diagnosis of active tuberculosis (TB) are paramount for the control of the disease. Epidemiological data are very powerful for contact tracing but might be delayed and/or difficult to integrate, especially in the setting of multiple contact-tracing investigations. The aim of this study was to address the added-value of whole-genome sequencing (WGS) to routine local TB surveillance systems. From November 2016 to July 2017, the local TB surveillance system identified three clusters that could constitute a unique larger outbreak. Epidemiological and clinical information were integrated with WGS genotyping data of Mycobacterium tuberculosis strains obtained using a simple DNA extraction method coupled with sequencing using an Illumina MiSeq platform and an in-house bioinformatics pipeline for single nucleotide polymorphism (SNP) analysis. Epidemiological investigations identified three putative TB clusters potentially interrelated including eight patients with active TB. Seven M. tuberculosis isolates were available and analysed by WGS. Using a 5-SNP threshold to define recent transmission, WGS-based genotyping supported the occurrence of the three clusters as well as a link between clusters 1 and 2 (SNP ≤1), constituting a larger outbreak. This outbreak was clearly delineated by refuting a potential link with the third cluster (SNP >500). Genotyping data did not support the belonging of patient 7 to any studied cluster. This study illustrates the usefulness of WGS genotyping for routine TB surveillance systems in local communities to rapidly confirm or disprove epidemiological hypotheses and delineate TB clusters, especially in the context of multiple contact-tracing investigations.

Blockade of endogenous IL-18 ameliorates TNBS-induced colitis by decreasing local TNF-alpha production in mice.

BACKGROUND & AIMS: Interleukin (IL) 18 has proinflammatory effects. IL-18 plays a pivotal role in Th1 responses, but its proinflammatory activities extend beyond Th1 cells, including macrophages and production of tumor necrosis factor (TNF) alpha and IL-1beta. IL-18 is up-regulated in colonic specimens of patients with Crohn's disease. The goal of this study was to evaluate the role of IL-18. METHODS: Activity of IL-18 was neutralized using recombinant human IL-18 binding protein isoform a (rhIL-18BPa) in trinitrobenzene sulfonic acid (TNBS)-induced colitis. RESULTS: Mice treated daily with rhIL-18BPa (8 mg/kg) had significant reductions in clinical score, body weight loss, and colon weight increase compared with saline-treated mice. Histologic analysis showed that rhIL-18BPa-treated mice developed only mild colitis without signs of ulceration, with a mean total score of 9.8 +/- 1.3 points compared with 15.9 +/- 1.1 points observed in saline-treated mice with colitis. Analysis of cytokine levels in colon homogenates showed a significant decrease in TNF-alpha, IL-6, and IL-1beta after rhIL-18BPa treatment but no effect on interferon gamma. The therapeutic potential of rhIL-18BPa treatment was confirmed in TNBS mice that were treated only on days 8 and 9 after the start of the experiment. In these mice, significant reductions in total colitis score and colon weight were also observed. CONCLUSIONS: These findings show that inhibition of rhIL-18BPa bioactivity, via rhIL-18BPa, may be beneficial for the treatment of IBD.

Expression of interleukin-18 in human atherosclerotic plaques and relation to plaque instability.

BACKGROUND: Interleukin (IL)-18 is a potent proinflammatory cytokine with potential atherogenic properties. Its expression and role in atherosclerosis, however, are unknown. METHODS AND RESULTS: In the present study, we examined stable and unstable human carotid atherosclerotic plaques retrieved by endarterectomy for the presence of IL-18 using reverse transcription-polymerase chain reaction (PCR), Western blot, and immunohistochemical techniques. IL-18 was highly expressed in the atherosclerotic plaques compared with control normal arteries and was localized mainly in plaque macrophages. IL-18 receptor was also upregulated in plaque macrophages and endothelial cells, suggesting potential biological effects. To examine the role of IL-18 in atherosclerosis, we determined the relation between IL-18 mRNA expression and signs of plaque instability using real-time quantitative PCR. Interestingly, significantly higher levels of IL-18 mRNA were found in symptomatic (unstable) plaques than asymptomatic (stable) plaques (P<0.01). CONCLUSIONS: These results suggest, for the first time, a major role for IL-18 in atherosclerotic plaque destabilization leading to acute ischemic syndromes.

Interleukin-18/interleukin-18 binding protein signaling modulates atherosclerotic lesion development and stability.

Interleukin (IL)-18 is the interferon-gamma-inducing factor and has other proinflammatory properties. The precise role of IL-18 in immunoinflammatory diseases remains poorly understood. In this study, we show that in vivo electrotransfer of an expression-plasmid DNA encoding for murine IL-18 binding protein (BP) (the endogenous inhibitor of IL-18) prevents fatty streak development in the thoracic aorta of apoE knockout mice and slows progression of advanced atherosclerotic plaques in the aortic sinus. More importantly, transfection with the IL-18BP plasmid induces profound changes in plaque composition (decrease in macrophage, T cell, cell death, and lipid content and increase in smooth muscle cell and collagen content) leading to a stable plaque phenotype. These results identify for the first time a critical role for IL-18/IL-18BP regulation in atherosclerosis and suggest a potential role for IL-18 inhibitors in reduction of plaque development/progression and promotion of plaque stability. The full text of this article is available at http://www.circresaha.org.