Nonpathogenic Cutibacterium acnes Confers Host Resistance against Staphylococcus aureus

Spatial Distribution and Functional Impact of Human Scalp Hair Follicle Microbiota

Human hair follicles (HFs) constitute a unique microbiota habitat that differs substantially from the skin surface. Traditional HF sampling methods fail to eliminate skin microbiota contaminants or assess the HF microbiota incompletely, and microbiota functions in human HF physiology remain ill explored. Therefore, we used laser-capture microdissection, metagenomic shotgun sequencing, and FISH to characterize the human scalp HF microbiota in defined anatomical compartments. This revealed significant compartment-, tissue lineage-, and donor age-dependent variations in microbiota composition. Greatest abundance variations between HF compartments were observed for viruses, archaea, Staphylococcus epidermidis, Cutibacterium acnes, and Malassezia restricta, with the latter 2 being the most abundant viable HF colonizers (as tested by propidium monoazide assay) and, surprisingly, most abundant in the HF mesenchyme. Transfection of organ-cultured human scalp HFs with S. epidermidis-specific lytic bacteriophages ex vivo downregulated transcription of genes known to regulate HF growth and development, metabolism, and melanogenesis, suggesting that selected microbial products may modulate HF functions. Indeed, HF treatment with butyrate, a metabolite of S. epidermidis and other HF microbiota, delayed catagen and promoted autophagy, mitochondrial activity, and gp100 and dermcidin expression ex vivo. Thus, human HF microbiota show spatial variations in abundance and modulate the physiology of their host, which invites therapeutic targeting.

Understanding the dynamic interactions of root-knot nematodes and their host: role of plant growth promoting bacteria and abiotic factors

Root-knot nematodes (Meloidogyne spp., RKN) are among the most destructive endoparasitic nematodes worldwide, often leading to a reduction of crop growth and yield. Insights into the dynamics of host-RKN interactions, especially in varied biotic and abiotic environments, could be pivotal in devising novel RKN mitigation measures. Plant growth-promoting bacteria (PGPB) involves different plant growth-enhancing activities such as biofertilization, pathogen suppression, and induction of systemic resistance. We summarized the up-to-date knowledge on the role of PGPB and abiotic factors such as soil pH, texture, structure, moisture, etc. in modulating RKN-host interactions. RKN are directly or indirectly affected by different PGPB, abiotic factors interplay in the interactions, and host responses to RKN infection. We highlighted the tripartite (host-RKN-PGPB) phenomenon with respect to (i) PGPB direct and indirect effect on RKN-host interactions; (ii) host influence in the selection and enrichment of PGPB in the rhizosphere; (iii) how soil microbes enhance RKN parasitism; (iv) influence of host in RKN-PGPB interactions, and (v) the role of abiotic factors in modulating the tripartite interactions. Furthermore, we discussed how different agricultural practices alter the interactions. Finally, we emphasized the importance of incorporating the knowledge of tripartite interactions in the integrated RKN management strategies.

Lactococcus kimchii extends lifespan and alleviates motility decline in Caenorhabditis elegans through ins-20, an insulin-like peptide gene

Lactococcus kimchii is isolated from commercial kimchi, which is a traditional Korean fermented food. This study was conducted to evaluate the probiotic effects of L. kimchii. Caenorhabditis elegans was fed L. kimchii, and its longevity, motility, and gene expression were examined. When fed a 1:1 mixture of Escherichia coli OP50 and L. kimchii (OP+LK), C. elegans had a significantly longer lifespan and increased locomotion than when it was fed OP alone. There was no significant difference in brood size between the OP+LK and OP groups, suggesting that these effects occurred in a dietary restriction-independent manner. RNA sequencing and Gene Ontology analysis showed that the expression of ins-20, an insulin-like peptide and agonist of the insulin receptor, was significantly upregulated in the OP+LK group. The ins-20 mutation annulled the effects of OP+LK on lifespan extension and motility. In addition, OP+LK failed to extend the lifespan of C. elegans deficient in daf-2, a receptor for the insulin-like signaling pathway. These results suggest that L. kimchii extends the lifespan and alleviates motility decline in C. elegans through the insulin signaling pathway, highlighting the potential of using L. kimchii as a beneficial bacterium for probiotics and postbiotics.

Pathogenicity of enterotoxigenic Escherichia coli in Caenorhabditis elegans as an alternative model host

Enterotoxigenic Escherichia coli (ETEC), one of the diarrheagenic E. coli, is the most common cause of diarrhea in developing country and in travelers to those areas. In this study, Caenorhabditis elegans was used as an alternative model host to evaluate ETEC infections. The ETEC strain ETEC1, which was isolated from a patient with diarrhea, possessed enterotoxins STh, LT1, and EAST1 and colonization factors CS2 and CS3. Live ETEC1 shortened the life span and body size of C. elegans in association with increased expression of enterotoxin genes and intestinal colonization. In contrast, heat-killed ETEC1 did not affect the life span of C. elegans. Caenorhabditis elegans infected with ETEC1 showed upregulated expression of genes related to insulin-like peptides and host defense responses. These results suggest that ETEC1 exhibits pathogenicity through intestinal colonization and enterotoxin production in C. elegans. This system is useful as an ETEC infection model.

Das kutane Mikrobiom bei Hautkrebs - Eine systematische Übersicht: The cutaneous microbiome in skin cancer - A systematic review

Die Hautkrebs‐Inzidenz ist über die vergangene halbe Dekade weltweit gestiegen und mit signifikanter Morbidität und Mortalität assoziiert. Jüngste Fortschritte in der molekularen Diagnostik ermöglichen ein besseres Verständnis von Mikrobiom‐Veränderungen bei diesen Erkrankungen. Allerdings ist die Literatur zum kutanen Mikrobiom bei Hautkrebs nach wie vor heterogen und spärlich. Wir führten eine systematische Überprüfung durch, um die bestehende Literatur sowie ihren Nutzen bezüglich mikrobiombasierter Biomarker zu evaluieren. Die Datenbanken (PubMed, Medline, EMBASE, GoogleScholar) wurden zwischen Juni und Juli 2022 in Übereinstimmung mit den PRISMA‐Richtlinien gesichtet.

Insgesamt wurden 1.543 Artikel ermittelt, von denen 16 in die Übersicht eingeschlossen wurden (11 Artikel zu epithelialen Hauttumoren und 5 Artikel zu Melanomen). Bei Plattenepithelkarzinomen (PEKs) und aktinischer Keratose (AK) wird im Vergleich zu gesunder Haut eine erhöhte Prävalenz von Staphylococcus (S.) aureus bei gleichzeitigem Rückgang der kommensalen Organismen festgestellt. Das Mikrobiom des Melanoms scheint sich zwar von dem der gesunden Haut zu unterscheiden, doch stehen nur wenige Daten für aussagekräftige Schlussfolgerungen zur Verfügung.

Die vorliegende Übersicht fasst die aktuellen Erkenntnisse zum Mikrobiom bei epithelialem Hautkrebs und Melanom zusammen. Sie zeigt, dass sich das Mikrobiom bei diesen Erkrankungen von dem gesunder Haut unterscheidet und dass an dieser Dysbiose sowohl pathogene als auch kommensale Organismen beteiligt sind.

The cutaneous microbiome in skin cancer - A systematic review

The overall incidence of skin cancer has risen over the past half a decade worldwide and is associated with significant morbidity and mortality. Recent advances in molecular testing have allowed us to better characterize microbiome alterations in skin cancer. However, literature specific to skin microbiome and skin cancer remain heterogenous and scattered. A systematic review was performed to identify the existing literature and its usefulness in providing microbiome-based biomarkers. A search of the databases (PubMed, Medline, EMBASE, GoogleScholar) was conducted from June to July 2022 in accordance with the PRISMA guidelines. A total of 1,543 articles were identified, of which 16 were selected for inclusion in the review (11 articles on cancer of the keratinocytes and 5 articles on melanoma). Increased Staphylococcus (S.) aureus prevalence with decline in commensal organisms is seen in squamous cell carcinoma (SCC) and actinic keratosis (AK), compared to healthy skin. While the microbiome of melanoma appears to be distinct from healthy skin, limited data is available to draw meaningful conclusions. Our review summarizes the current evidence on the microbiome of keratinocyte skin cancers and melanoma. The study establishes that the microbiome of these cancers is altered from healthy skin and that this dysbiosis involves both pathogenic and commensal organisms.

Microbe Interactions within the Skin Microbiome

The skin is the largest human organ and is responsible for many important functions, such as temperature regulation, water transport, and protection from external insults. It is colonized by several microorganisms that interact with each other and with the host, shaping the microbial structure and community dynamics. Through these interactions, the skin microbiota can inhibit pathogens through several mechanisms such as the production of bacteriocins, proteases, phenol soluble modulins (PSMs), and fermentation. Furthermore, these commensals can produce molecules with antivirulence activity, reducing the potential of these pathogens to adhere to and invade human tissues. Microorganisms of the skin microbiota are also able to sense molecules from the environment and shape their behavior in response to these signals through the modulation of gene expression. Additionally, microbiota-derived compounds can affect pathogen gene expression, including the expression of virulence determinants. Although most studies related to microbial interactions in the skin have been directed towards elucidating competition mechanisms, microorganisms can also use the products of other species to their benefit. In this review, we will discuss several mechanisms through which microorganisms interact in the skin and the biotechnological applications of products originating from the skin microbiota that have already been reported in the literature.

Activity of root-knot nematodes associated with composition of a nematode-attached microbiome and the surrounding soil microbiota

We investigated if activity of the pre-infective juveniles (J2s) of root-knot nematodes is linked to the recruitment of a specific microbiome on the nematode surface and/or to the composition of the surrounding microbiota. For this, we determined the J2 activity (active vs. non-motile, which referred to dead and immobile J2s) upon a 3-day incubation in soil suspensions and studied the composition of bacteria, protists, and fungi present on the nematode surface and in the suspensions using amplicon sequencing of the 16S/18S rRNA genes, and ITS region. We also amended suspensions with Pseudomonas protegens strain CHA0 to study its effects on J2 activity and microbial composition. The J2 activity was suppressed in soil suspensions, but increased when suspensions were amended with P. protegens CHA0. The active and non-motile J2s differed in the composition of surface-attached bacteria, which was altered by the presence of P. protegens CHA0 in the soil suspensions. The bacterial genera Algoriphagus, Pedobacter, and Bdellovibrio were enriched on active J2s and may have protected the J2s against antagonists. The incubation time appeared short for attachment of fungi and protists. Altogether, our study is a step forward in disentangling the complex nematode-microbe interactions in soil for more successful nematode control.

The increasing importance of the gut microbiome in acne vulgaris

Acne is a frequently presented dermatological condition brought about by an interplay among inflammation, increased sebum production, hyperkeratinisation, and predominantly Propionibacterium acnes (renamed as Cutibacterium acnes) proliferation, leading to debilitating psychological scars. However, it has been shown that it is the loss of microbial diversity in the skin and the imbalance among C. acnes phylotypes that brings about acne rather than the C. acnes species as a whole. Interestingly, recent evidence suggests that other microorganisms may be implicated, such as the fungi Malassezia and the bacteria Cutibacterium granulosum. A plethora of scientific evidence suggests that the gut microbiome is implicated in the overall health and physiology of the host; studies show that the gut microbiome of acne patients is distinct and depicts less microbial diversity compared to individuals without acne. Herein, using the key terms: acne, C. acnes, IGF-1, sebum, and gut microbiome, we carried out a review of the literature, using Google Scholar and PubMed, and discussed the role of the gut and skin microbiome in relation to acne, as a narrative review. The role of hormones, diet, sebum, and stress in relation to the gut microbiome was also investigated. Therapeutic implications and the use of pre-/postbiotics are also deliberated upon. In this light, future research should investigate the relationship between the gut microbiome and the agreed upon factors of acne pathology, potentially leading to the discovery of novel acne treatments with milder side effects.

The defense response of Caenorhabditis elegans to Cutibacterium acnes SK137 via the TIR-1-p38 MAPK signaling pathway

Cutibacterium acnes plays roles in both acne disease and healthy skin ecosystem. We observed that mutations in the tir-1/SARM1 and p38 MAPK cascade genes significantly shortened Caenorhabditis elegans lifespan upon Cutibacterium acnes SK137 infection. Antimicrobial molecules were induced by SK137 in a TIR-1-dependent manner. These results suggest that defense responses against SK137 involve the TIR-1-p38 MAPK pathway in Caenorhabditis elegans.