Studies have emphasized the importance of disease-associated microorganisms in perturbed communities, however, the protective roles of commensals are largely under recognized and poorly understood. Using acne as a model disease, we investigated the determinants of the overall virulence property of the skin microbiota when disease- and health-associated organisms coexist in the community. By ultra-deep metagenomic shotgun sequencing, we revealed higher relative abundances of propionibacteria and Propionibacterium acnes phage in healthy skin. In acne patients, the microbiome composition at the species level and at P. acnes strain level was more diverse than in healthy individuals, with enriched virulence-associated factors and reduced abundance of metabolic synthesis genes. Based on the abundance profiles of the metagenomic elements, we constructed a quantitative prediction model, which classified the clinical states of the host skin with high accuracy in both our study cohort (85%) and an independent sample set (86%). Our results suggest that the balance between metagenomic elements, not the mere presence of disease-associated strains, shapes the overall virulence property of the skin microbiota. This study provides new insights into the microbial mechanism of acne pathogenesis and suggests probiotic and phage therapies as potential acne treatments to modulate the skin microbiota and to maintain skin health.

In China, stroke is a major cause of mortality, and long-term physical and cognitive impairment. To meet this challenge, the Ministry of Health China Stroke Prevention Project Committee (CSPPC) was established in April 2011. This committee actively promotes stroke prevention and control in China. With government financial support of 838.4 million CNY, 8.352 million people from 536 screening points in 31 provinces have received stroke screening and follow-up over the last seven years (2012–2018). In 2016, the CSPPC issued a plan to establish stroke centers. To shorten the pre-hospital period, the CSPPC established a stroke center network, stroke map, and stroke “Green Channel” to create three 1-h gold rescue circles, abbreviated as “1-1-1” (onset to call time <1 h; pre-hospital transfer time < 1 h, and door-to-needle time < 1 h). From 2017 to 2018, the median door-to-needle time dropped by 4.0% (95% confidence interval (CI), 1.4–9.4) from 50 min to 48 min, and the median onset-to-needle time dropped by 2.8% (95% CI, 0.4–5.2) from 180 min to 175 min. As of 31 December 2018, the CSPPC has established 380 stroke centers in mainland China. From 1 November 2018, the CSPPC has monitored the quality of stroke care in stroke center hospitals through the China Stroke Data Center Data Reporting Platform. The CSPPC Stroke program has led to a significant improvement in stroke care. This program needs to be further promoted nationwide.

Various diseases have been linked to the human microbiota, but the underlying molecular mechanisms of the microbiota in disease pathogenesis are often poorly understood. Using acne as a disease model, we aim to understand the molecular response of the skin microbiota to host metabolite signaling in disease pathogenesis. By metatranscriptomic analysis, we found that the transcriptional profiles of the skin microbiota separated acne patients from healthy individuals. The vitamin B12 biosynthesis pathway in the skin bacterium, Propionibacterium acnes, was significantly down-regulated in acne patients. We hypothesized that host vitamin B12 modulates the activities of the skin microbiota and plays a role in acne pathogenesis. To test this hypothesis, we analyzed the skin microbiota in healthy subjects supplemented with vitamin B12. We found that the supplementation repressed the expression of vitamin B12 biosynthesis genes in P. acnes and altered the transcriptome of the skin microbiota. One of the ten subjects studied developed acne one week after vitamin B12 supplementation. To further understand the molecular mechanism, we revealed that vitamin B12 supplementation in P. acnes cultures promoted the production of porphyrins, which are known to induce inflammation in acne. Our findings suggest a new bacterial pathogenesis pathway in acne and provide one molecular explanation for the long-standing clinical observation that vitamin B12 supplementation leads to acne development. Our study discovered that vitamin B12, an essential nutrient in humans, modulates the transcriptional activities of the skin bacteria, and provided evidence that metabolite-mediated interactions between the host and the skin microbiota play essential roles in disease development.

Propionibacterium acnes is a dominant bacterium residing on skin, and it has been thought to play a causal role in several diseases including acne, a common skin disease affecting more than 80% of people worldwide. While specific strains of P. acnes have been associated with either disease or healthy skin, the mechanisms remain unclear. Recently, we showed that vitamin B12 supplementation increased porphyrin production in P. acnes, leading to acne development (D. Kang, B. Shi, M. C. Erfe, N. Craft, and H. Li, Sci. Transl. Med. 7:293ra103, 2015, doi:10.1126/scitranslmed.aab2009). Here, we reveal that the levels of porphyrin production and vitamin B12 regulation are different between acne- and health-associated strains, suggesting a potential molecular mechanism for disease-associated strains in acne pathogenesis and for health-associated strains in skin health. This study highlights the importance of understanding the strain-level differences of the human microbiota in disease pathogenesis. Our findings also suggest the porphyrin biosynthesis pathway as a candidate drug target and use of health-associated strains as potential probiotics in novel acne therapeutics.

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