Laser capture microdissection as a method for investigating the human hair follicle microbiome reveals region-specific differences in the bacteriome profile.

OBJECTIVE: Human hair follicles (HFs) are populated by a rich and diverse microbiome, traditionally evaluated by methods that inadvertently sample the skin microbiome and/or miss microbiota located in deeper HF regions. Thereby, these methods capture the human HF microbiome in a skewed and incomplete manner. This pilot study aimed to use laser-capture microdissection of human scalp HFs, coupled with 16S rRNA gene sequencing to sample the HF microbiome and overcome these methodological limitations. RESULTS: HFs were laser-capture microdissected (LCM) into three anatomically distinct regions. All main known core HF bacterial colonisers, including Cutibacterium, Corynebacterium and Staphylococcus, were identified, in all three HF regions. Interestingly, region-specific variations in α-diversity and microbial abundance of the core microbiome genera and Reyranella were identified, suggestive of variations in microbiologically relevant microenvironment characteristics. This pilot study therefore shows that LCM-coupled with metagenomics is a powerful tool for analysing the microbiome of defined biological niches. Refining and complementing this method with broader metagenomic techniques will facilitate the mapping of dysbiotic events associated with HF diseases and targeted therapeutic interventions.

Lifestyle of sponge symbiont phages by host prediction and correlative microscopy.

Bacteriophages (phages) are ubiquitous elements in nature, but their ecology and role in animals remains little understood. Sponges represent the oldest known extant animal-microbe symbiosis and are associated with dense and diverse microbial consortia. Here we investigate the tripartite interaction between phages, bacterial symbionts, and the sponge host. We combined imaging and bioinformatics to tackle important questions on who the phage hosts are and what the replication mode and spatial distribution within the animal is. This approach led to the discovery of distinct phage-microbe infection networks in sponge versus seawater microbiomes. A new correlative in situ imaging approach ('PhageFISH-CLEM') localised phages within bacterial symbiont cells, but also within phagocytotically active sponge cells. We postulate that the phagocytosis of free virions by sponge cells modulates phage-bacteria ratios and ultimately controls infection dynamics. Prediction of phage replication strategies indicated a distinct pattern, where lysogeny dominates the sponge microbiome, likely fostered by sponge host-mediated virion clearance, while lysis dominates in seawater. Collectively, this work provides new insights into phage ecology within sponges, highlighting the importance of tripartite animal-phage-bacterium interplay in holobiont functioning. We anticipate that our imaging approach will be instrumental to further understanding of viral distribution and cellular association in animal hosts.

Exploring the human hair follicle microbiome.

Human hair follicles (HFs) carry complex microbial communities that differ from the skin surface microbiota. This likely reflects that the HF epithelium differs from the epidermal barrier in that it provides a moist, less acidic, and relatively ultraviolet light-protected environment, part of which is immune-privileged, thus facilitating microbial survival. Here we review the current understanding of the human HF microbiome and its potential physiological and pathological functions, including in folliculitis, acne vulgaris, hidradenitis suppurativa, alopecia areata and cicatricial alopecias. While reviewing the main human HF bacteria (such as Propionibacteria, Corynebacteria, Staphylococci and Streptococci), viruses, fungi and parasites as human HF microbiome constituents, we advocate a broad view of the HF as an integral part of the human holobiont. Specifically, we explore how the human HF may manage its microbiome via the regulated production of antimicrobial peptides (such as cathelicidin, psoriasin, RNAse7 and dermcidin) by HF keratinocytes, how the microbiome may impact on cytokine and chemokine release from the HF, and examine hair growth-modulatory effects of antibiotics, and ask whether the microbiome affects hair growth in turn. We highlight major open questions and potential novel approaches to the management of hair diseases by targeting the HF microbiome.

Fluorescence-based quasicontinuous and in situ monitoring of biofilm formation dynamics in natural marine environments.

Analyzing the dynamics of biofilm formation helps to deepen our understanding of surface colonization in natural environments. While methods for screening biofilm formation in the laboratory are well established, studies in marine environments have so far been based upon destructive analysis of individual samples and provide only discontinuous snapshots of biofilm establishment. In order to explore the development of biofilm over time and under various biotic and abiotic conditions, we applied a recently developed optical biofilm sensor to quasicontinuously analyze marine biofilm dynamics in situ. Using this technique in combination with microscope-assisted imaging, we investigated biofilm formation from its beginning to mature multispecies biofilms. In contrast to laboratory studies on biofilm formation, a smooth transition from initial attachment to colony formation and exponential growth could not be observed in the marine environment. Instead, initial attachment was followed by an adaptation phase of low growth and homogeneously distributed solitary bacterial cells. Moreover, we observed a diurnal variation of biofilm signal intensity, suggesting a transient state of biofilm formation of bacteria. Overall, the biofilm formation dynamics could be modeled by three consecutive development stages attributed to initial bacterial attachment, bacterial growth, and attachment and growth of unicellular eukaryotic microorganisms. Additional experiments showed that the presence of seaweed considerably shortened the adaptation phase in comparison with that on control surfaces but yielded similar growth rates. The outlined examples highlight the advantages of a quasicontinuous in situ detection that enabled, for the first time, the exploration of the initial attachment phase and the diurnal variation during biofilm formation in natural ecosystems.

Long-term effects of childhood sexual abuse: objective and subjective characteristics of the abuse and psychopathology in later life.

This study investigates the association between objective and subjective characteristics of childhood sexual abuse and psychopathology in later life. The sample consists of 404 Dutch female adults who had been sexually abused in their childhood or adolescence. The participants were recruited by means of articles about childhood sexual abuse in major Dutch newspapers. The characteristics and severity of the sexual abuse were assessed with the Questionnaire Unwanted Sexual Experiences in the Past (QUSEP). General psychopathology was measured with the Symptom Checklist (SCL-90), the degree of dissociation was measured with the Dissociation Questionnaire (DIS-Q). Stepwise multiple regression analyses showed a moderate association between psychopathology and objective characteristics of the abuse, such as number of different types of abusive events and the duration of the abuse. However, more strongly associated with later psychopathology were variables reflecting coping style, such as the degree of self-blame, and circumstantial factors, such as the emotional atmosphere in the family of origin and the reactions after disclosure. Whether or not the abuse was incestuous did not explain additional variance in later psychopathology.