Heat-killed Lacticaseibacillus paracasei GMNL-653 ameliorates human scalp health by regulating scalp microbiome.

BACKGROUND: The equilibrium of the scalp microbiome is important for maintaining healthy scalp conditions, including sebum secretion, dandruff, and hair growth. Many different strategies to improve scalp health have been reported; however, the effect of postbiotics, such as heat-killed probiotics, on scalp health remains unclear. We examined the beneficial effects of heat-killed probiotics consisting of Lacticaseibacillus paracasei, GMNL-653, on scalp health. RESULTS: Heat-killed GMNL-653 could co-aggregate with scalp commensal fungi, Malassezia furfur, in vitro, and the GMNL-653-derived lipoteichoic acid inhibited the biofilm formation of M. furfur on Hs68 fibroblast cells. The mRNA of hair follicle growth factors, including insulin-like growth factor-1 receptor (IGF-1R), vascular endothelial growth factor, IGF-1, and keratinocyte growth factor was up-regulated in skin-related human cell lines Hs68 and HaCaT after treatment with heat-killed GMNL-653. For clinical observations, we recruited 22 volunteer participants to use the shampoo containing the heat-killed GMNL-653 for 5 months and subsequently measured their scalp conditions, including sebum secretion, dandruff formation, and hair growth. We applied polymerase chain reaction (PCR) to detect the scalp microbiota of M. restricta, M. globosa, Cutibacterium acnes, and Staphylococcus epidermidis. A decrease in dandruff and oil secretion and an increase in hair growth in the human scalp were observed after the use of heat-killed GMNL-653-containing shampoo. The increased abundance of M. globosa and the decreased abundance of M. restricta and C. acnes were also observed. We further found that accumulated L. paracasei abundance was positively correlated with M. globosa abundance and negatively correlated with C. acnes abundance. S. epidermidis and C. acnes abundance was negatively correlated with M. globosa abundance and positively correlated with M. restricta. Meanwhile, M. globosa and M. restricta abundances were negatively associated with each other. C. acnes and S. epidermidis abundances were statistically positively correlated with sebum secretion and dandruff, respectively, in our shampoo clinical trial. CONCLUSION: Our study provides a new strategy for human scalp health care using the heat-killed probiotics GMNL-653-containing shampoo. The mechanism may be correlated with the microbiota shift.

Malassezia and Staphylococcus dominate scalp microbiome for seborrheic dermatitis.

Seborrheic dermatitis (SD) is a common disease of the human scalp that causes physical damage and psychological problems for patients. Studies have indicated that dysbiosis of the scalp microbiome results in SD. However, the specific fungal and bacterial microbiome changes related to SD remain elusive. To further investigate the fungal and bacterial microbiome changes associated with SD, we recruited 57 SD patients and 53 healthy individuals and explored their scalp microbiomes using next generation sequencing and the QIIME and LEfSe bioinformatics tools. Skin pH, sebum secretion, hydration, and trans-epidermal water loss (TWEL) were also measured at the scalp. We found no statistically significant differences between the normal and lesion sites in SD patients with different subtypes of dandruff and erythema. However, the fungal and bacterial microbiome could differentiate SD patients from healthy controls. The presence of Malassezia and Aspergillus was both found to be potential fungal biomarkers for SD, while Staphylococcus and Pseudomonas were found to be potential bacterial biomarkers. The fungal and bacterial microbiome were divided into three clusters through co-abundance analysis and their correlations with host factors indicated the interactions and potential cooperation and resistance between microbe communities and host. Our research showed the skin microbe dysbiosis of SD and highlighted specific microorganisms that may serve as potential biomarkers of SD. The etiology of SD is multi-pathogenetic-dependent on the linkage of several microbes with host. Scalp microbiome homeostasis could be a promising new target in the risk assessment, prevention, and treatment of SD disease.

Collapse of human scalp microbiome network in dandruff and seborrhoeic dermatitis.

We investigate the relationship between scalp microbiota and dandruff/seborrhoeic dermatitis (D/SD), an unpleasant scalp disorder common in human populations. Bacterial and fungal community analyses on scalp of 102 Korean were performed by next-generation sequencing. Overall scalp microbiome composition significantly differed between normal and disease groups, and especially co-occurrence network of dominant members was breakdown in disease groups. These findings will provide novel insights into shifts of microbial community relevant to D/SD.

COMPARATIVE WHOLE METAGENOME ANALYSIS IN LESIONAL AND NON-LESIONAL SCALP AREAS OF PSORIASIS CAPITIS PATIENTS AND HEALTHY INDIVIDUALS.

Psoriasis is an immune-mediated inflammatory disorder, where the majority of the patients suffer from psoriasis capitis or scalp psoriasis. Current therapeutics remain ineffective to treat scalp lesions. Here, we present a whole-metagenome characterisation of the scalp microbiome in psoriasis capitis. We investigated how changes in the homeostatic cutaneous microbiome correlate with the condition and identified metagenomic biomarkers (taxonomic, functional, virulence factors, antimicrobial resistance genes) that could partly explain its emergence. Within this study, 83 top and back scalp samples from healthy individuals and 64 lesional and non-lesional scalp samples from untreated psoriasis capitis subjects were analysed. Using qPCR targeting the 16S and 18S rRNA genes, we found a significant decrease in microbial load within scalp regions affected by psoriasis compared to their non-lesional counterparts. Metagenomic analysis revealed that psoriatic lesions displayed significant lower Cutibacterium species (incl. C. modestum, C. namnetense, C. granulosum, C. porci), along with an elevation in Staphylococcus aureus. A heightened relative presence of efflux pump protein-encoding genes was detected, suggesting potential antimicrobial resistance mechanisms. These mechanisms are known to specifically target human antimicrobial peptides (incl. cathelicidin LL-37) which are frequently encountered within psoriasis lesions. These shifts in microbial community dynamics may contribute to psoriasis disease pathogenesis.

A comprehensive literature review and an international expert consensus on the management of scalp seborrheic dermatitis in adults.

Seborrheic Dermatitis of the scalp (SSD) is a chronic and relapsing inflammatory skin condition. Current SSD treatments mainly consist of topical applications of anti-fungals and anti-inflammatory agents. to review information about SSD and to provide dermatologists with practical recommendations for managing adult SSD. Material and methods: Between September and December 2023, an international group of experts in dermatology and hair and scalp disorders met to discuss published data about SD, SSD, dandruff, and management options. A total of 131 manuscripts available from PubMed were analysed, discussed and used for the present consensus. Each author was asked to complete a table listing currently used treatments to treat SSD according to the literature and to their own experience. The authors confirmed their use and regimen and commented on local treatment exceptions. They then agreed on prescription practices and proposed a general treatment approach. Currently, approved therapies to manage moderate and severe forms of SSD do not exist and there is a need for adapted and approved medications that treat efficiently and safely the disease. We propose a treatment algorithm that allows for the treatment of all severity grades of SSD. This algorithm may be completed with local treatment specifications. Despite the lack of approved therapies to manage moderate forms of SSD, a treatment algorithm is proposed and may help prescribers to manage SSD more efficiently.

Effects of a Postbiotic Saccharomyces and Lactobacillus Ferment Complex on the Scalp Microbiome of Chinese Women with Sensitive Scalp Syndrome.

Introduction: Sensitive scalp is one of the most frequent complaints related to sensitive skin syndrome, characterized by unpleasant sensory reactions in the absence of visible signs of inflammation. In this study, the effects of topical application of postbiotic Himalaya-derived Saccharomyces and Lactobacillus ferment complex (SLFC) on the bacterial and fungal scalp microbiome at the taxonomic level and alleviation of sensitive skin syndrome were investigated. Methods: Firstly, healthy female participants (aged 30-45) were classified into a healthy scalp group and a sensitive scalp group based on the questionnaire. Thereafter, topical application of SLFC on sensitive scalp as well as scalp microbiome was evaluated, with the difference in the distribution of microbial taxa between healthy and sensitive scalp communities was assessed using 16S rRNA and ITS1 sequencing analysis. In addition, the effect of SLFC on scalp microbiome at the species level for Cutibacterium acnes, Staphylococcus epidermidis, and Malassezia restricta was evaluated by the qPCR assessment. Results: After treatment with SLFC for 28 days, the abundance of Staphylococcus, Lawsonella, and Fusarium in the sensitive scalp group was highly significantly increased (p < 0.001), while the abundance of Cutibacterium and Malassezia was highly significantly decreased (p < 0.001). Furthermore, the self-assessment questionnaire indicated a syndrome alleviation effect of 100% after 28 days with a twice-daily application of the SLFC. Discussion: The obtained results would help to better understand the microbial community of the sensitive scalp and provide useful information on utilization of SLFC for maintaining a healthy scalp and modulating the scalp microbiome.

Comparative analysis of scalp and gut microbiome in androgenetic alopecia: A Korean cross-sectional study.

Androgenetic alopecia (AGA) is a non-scarring and progressive form of hair loss occurring in both men and women. Although genetic predisposition and sex steroid hormones are the main causes, many factors remain unknown, and various extrinsic factors can negatively affect the lifespan of hair. We investigated skin-gut axis microorganisms as potential exogenous factors causing AGA, through comparative analyses of the scalp and gut microbiome in individuals with and without AGA in a Korean cohort. Using 16S rRNA gene sequencing, we characterized the scalp and gut microbiomes of 141 individuals divided into groups by sex and presence of AGA. Alpha diversity indices in the scalp microbiome were generally higher in individuals with AGA than in healthy controls. These indices showed a strong negative correlation with scalp-inhabitant bacteria (Cutibacterium and Staphylococcus), indicating that the appearance of non-inhabitant bacteria increases as hair loss progresses. No significant differences in diversity were observed between the gut microbiomes. However, bacterial functional differences, such as bile acid synthesis and bacterial invasion of epithelial cells, which are related to intestinal homeostasis, were observed. The networks of the scalp and gut microbiome were more complex and denser with higher values of the network topology statistic coefficient values (i.e., transitivity, density, and degree centrality) and more unique associations in individuals with AGA than in healthy controls. Our findings reveal a link between skin-gut microorganisms and AGA, indicating the former's potential involvement in the latter's development. Additionally, these results provide evidence for the development of cosmetics and therapeutics using microorganisms and metabolites involved in AGA.

A Potential Predictive Role of the Scalp Microbiome Profiling in Patients with Alopecia Areata: Staphylococcus caprae, Corynebacterium, and Cutibacterium Species.

Little is known about the scalp bacterial composition of alopecia areata (AA) patients. The aim of this study was to investigate the differences in the scalp microbiome of AA patients according to their prognosis, in addition to healthy controls. A total of 33 AA patients and 12 healthy controls (HC) were included in this study. The microbiomes were characterized by sequencing 16S rRNA genes on the Illumina MiSeq platform. The scalp microbiome was more diverse in AA patients compared to HC, but not significantly different according to the severity of AA. Nevertheless, the higher proportion of Corynebacterium species and the lower proportion of Staphylococcus caprae among the Staphylococcus species were noticed in severe AA patients compared to HC or mild AA. The higher ratio of Cutibacterium species to S. caprae was noticed in severe AA. We highlight the potential predictive role of scalp microbiome profiling to a worse prognosis of patients with alopecia areata.

Predictive Metagenomic Profiling, Urine Metabolomics, and Human Marker Gene Expression as an Integrated Approach to Study Alopecia Areata.

Involvement of the microbiome in many different scalp conditions has been investigated over the years. Studies on the role of the scalp microbiome in specific diseases, such as those involving hair growth alterations like non-cicatricial [androgenetic alopecia (AGA), alopecia areata (AA)] and cicatricial alopecia lichen planopilaris, are of major importance. In the present work, we highlighted the differences in microbial populations inhabiting the scalp of AA subjects and a healthy sample cohort by using an integrated approach relying on metagenomic targeted 16S sequencing analysis, urine metabolomics, and human marker gene expression. Significant differences in genera abundances (p < 0.05) were found in the hypodermis and especially the dermis layer. Based on 16S sequencing data, we explored the differences in predicted KEGG pathways and identified some significant differences in predicted pathways related to the AA pathologic condition such as flagellar, assembly, bacterial chemotaxis, mineral absorption, ABC transporters, cellular antigens, glycosaminoglycan degradation, lysosome, sphingolipid metabolism, cell division, protein digestion and absorption, and energy metabolism. All predicted pathways were significantly enhanced in AA samples compared to expression in healthy samples, with the exceptions of mineral absorption, and ABC transporters. We also determined the expression of TNF-α, FAS, KCNA3, NOD-2, and SOD-2 genes and explored the relationships between human gene expression levels and microbiome composition by Pearson's correlation analysis; here, significant correlations both positive (SOD vs. Staphylococcus, Candidatus Aquiluna) and negative (FAS and SOD2 vs. Anaerococcus, Neisseria, and Acinetobacter) were highlighted. Finally, we inspected volatile organic metabolite profiles in urinary samples and detected statistically significant differences (menthol, methanethiol, dihydrodehydro-beta-ionone, 2,5-dimethylfuran, 1,2,3,4, tetrahydro-1,5,7-trimethylnapthalene) when comparing AA and healthy subject groups. This multiple comparison approach highlighted potential traits associated with AA and their relationship with the microbiota inhabiting the scalp, opening up novel therapeutic interventions in such kind of hair growth disorders mainly by means of prebiotics, probiotics, and postbiotics.

Comparison of Healthy and Dandruff Scalp Microbiome Reveals the Role of Commensals in Scalp Health.

Several scalp microbiome studies from different populations have revealed the association of dandruff with bacterial and fungal dysbiosis. However, the functional role of scalp microbiota in scalp disorders and health remains scarcely explored. Here, we examined the bacterial and fungal diversity of the scalp microbiome and their potential functional role in the healthy and dandruff scalp of 140 Indian women. Propionibacterium acnes and Staphylococcus epidermidis emerged as the core bacterial species, where the former was associated with a healthy scalp and the latter with dandruff scalp. Along with the commonly occurring Malassezia species (M. restricta and M. globosa) on the scalp, a strikingly high association of dandruff with yet uncharacterized Malassezia species was observed in the core mycobiome. Functional analysis showed that the fungal microbiome was enriched in pathways majorly implicated in cell-host adhesion in the dandruff scalp, while the bacterial microbiome showed a conspicuous enrichment of pathways related to the synthesis and metabolism of amino acids, biotin, and other B-vitamins, which are reported as essential nutrients for hair growth. A systematic measurement of scalp clinical and physiological parameters was also carried out, which showed significant correlations with the microbiome and their associated functional pathways. The results point toward a new potential role of bacterial commensals in maintaining the scalp nutrient homoeostasis and highlights an important and yet unknown role of the scalp microbiome, similar to the gut microbiome. This study, therefore, provides new perspectives on the better understanding of the pathophysiology of dandruff.