Singapore's research landscape has long been at the forefront of biomedical innovation, and a groundbreaking study from the Agency for Science, Technology and Research (A*STAR) is pushing the boundaries of skin microbiome science. Led by Dr. Minghao Chia at the A*STAR Genome Institute of Singapore (GIS), the research unveils previously invisible microbial activities on human skin using a novel RNA-based metatranscriptomics approach. Published in the prestigious journal Nature Biotechnology, this work not only refines our understanding of the skin's microbial ecosystem but also holds promise for revolutionizing treatments for common conditions like eczema and acne, which affect millions globally and are particularly prevalent in tropical climates like Singapore's.
The skin, our body's largest organ, hosts a dynamic community of bacteria, fungi, and other microbes collectively known as the skin microbiome. While DNA sequencing—metagenomics—has cataloged who lives there, it falls short in revealing what these microbes are doing. Are they dormant passengers or active influencers of health? The A*STAR team's method bridges this gap by capturing RNA transcripts, the molecules that indicate gene expression and thus real-time activity.
The Challenges of Studying the Skin Microbiome
Traditional microbiome studies face significant hurdles on the skin. Microbial biomass is low compared to the gut, making RNA extraction tricky. Human cells contaminate samples, and RNA degrades quickly. Previous attempts at skin metatranscriptomics yielded inconsistent results, limiting insights into functional roles.
In Singapore, where humid conditions foster unique microbial niches, these challenges are amplified. Eczema, or atopic dermatitis, affects about 20% of children and 11% of adults here—a higher rate than global averages—while acne impacts over 50% of young adults in Asian populations, including Singaporean Chinese. Understanding active microbial contributions could unlock targeted therapies tailored to local environments.
A Breakthrough RNA Workflow: Step-by-Step Innovation
The A*STAR workflow starts with non-invasive swabs from five skin sites: scalp, cheek, antecubital fossa (elbow crease), volar forearm, and toe web. Samples are preserved in DNA/RNA Shield and processed via bead beating for lysis, followed by rRNA depletion using custom probes targeting microbial ribosomal RNA. TRIzol extraction yields high-quality RNA, sequenced with Illumina platforms after library prep.
Bioinformatics is key: A custom Nextflow pipeline removes host reads, classifies taxonomy with Kraken2/Bracken, and annotates functions using a skin-specific gene catalog (iHSMGC). Paired metagenomics normalizes for abundance, yielding RNA/DNA ratios that spotlight activity.
This reproducible method (Sørensen similarity >0.98 at species level) outperforms prior techniques, enabling population-scale studies.
Key Findings: Activity Trumps Abundance
Analyzing 27 healthy Singaporean adults, the study revealed striking discordance. Staphylococcus species and Malassezia fungi dominated metatranscriptomes (up to 81% RNA contribution) despite modest DNA presence. Cutibacterium acnes, acne-associated, was abundant but less transcriptionally active (2-31%).
Low-abundance microbes punch above their weight due to larger cells (Malassezia) or high metabolic rates. Core pathways like fatty acid beta-oxidation were driven by these "quiet giants."
Site-Specific Microbial Adaptations
Microbes tailor gene expression to niches. On the scalp, Malassezia restricta upregulated fructose metabolism; on cheeks, glycerophospholipid pathways. S. epidermidis showed distinct in vivo vs. lab transcriptomes, exporting more propionate—a short-chain fatty acid bolstering the skin barrier.
These adaptations highlight environmental responses, e.g., sebum-rich areas favoring lipid metabolism.
Antimicrobial Genes and Microbial Wars
Skin commensals produce diverse antimicrobials in situ, including novel bacteriocins. C. acnes cutimycin and staphylococcal lacticin 481 correlated negatively with competitors like S. hominis. Over 20 genes mediated interactions, shaping community structure.
M. restricta protein DNF11_2196 suppressed C. acnes, suggesting balance mechanisms.
| Microbe | Antimicrobial | Target/Effect |
|---|---|---|
| C. acnes | Cutimycin | Inhibits Gram-positives |
| S. epidermidis | Lacticin 481 | Reduces S. hominis |
| M. restricta | DNF11_2196 | Suppresses C. acnes |
Implications for Eczema Research
Eczema in Singapore burdens healthcare, with flares linked to microbial dysbiosis. The study notes S. aureus sspA transcripts elevated in atopic dermatitis, inducing itch via serine protease activity. S. capitis correlates with Th17 pathways and IL-6/JAK/STAT3 signaling, key in eczema inflammation.
Malassezia proteases degrade host filaggrin, weakening barriers. Propionate from S. epidermidis could counter this, suggesting probiotic potentials. Future: Track flare predictors via metatranscriptomics.Singapore Ministry of Health eczema overview
Transforming Acne Treatment Paradigms
Acne affects 56% of Singaporean Chinese youth. C. acnes vitamin B12 downregulation links to porphyrin-induced inflammation. Thiopeptide antimicrobials from C. acnes may modulate virulence.
Active Staphylococcus could compete, offering live biotherapeutic avenues. Personalized profiles might guide topicals avoiding resistance.Full study in Nature Biotechnology
Singapore's Thriving Research Ecosystem
A*STAR GIS and SRL exemplify Singapore's biomedical hub. Collaborations with NUS (e.g., Nagarajan's adjunct role) and NTU amplify impact. The Asian Skin Microbiome Project (ASMP) builds on this, targeting dandruff, eczema.
Government funding via NMRC supports translation, positioning Singapore for microbiome therapeutics leadership.
Future Outlook: From Bench to Clinic
This workflow scales to diseased cohorts, identifying flare biomarkers or therapeutic targets. Probiotics enhancing beneficial activity (e.g., propionate producers) or antimicrobials could emerge. In Singapore's humid climate, site-specific insights tailor interventions.
Challenges: Larger Asian cohorts, longitudinal studies. Potential: Microbiome-modulating cosmetics, vaccines for acne/eczema.
Stakeholder Perspectives and Actionable Insights
Dr. Chia: "We can now see what skin microbes are doing, enriching our view of communities." Dr. Nagarajan: "Profiles microbial activity for prediction, diagnosis, treatment."
- Clinicians: Integrate metatranscriptomics for precision dermatology.
- Researchers: Use open datasets (ENA PRJEB89273) for meta-analyses.
- Industry: Develop actives targeting secretory pathways.
- Patients: Maintain barrier via gentle cleansing, probiotics.
