The dialogue between unconventional T cells and the microbiota

Lin, Qiaochu; Kuypers, Meggie; Philpott, Dana J.; Mallevaey, Thierry

doi:10.1038/s41385-020-0326-2

“…Commensal microbes control mucosal-associated invariant T (MAIT) cells. These are an evolutionarily conserved T-cell subset, which represents the most abundant T-cell subset recognizing bacterial compounds [ 55 , 56 ]. They react to many bacterial species through T-cell receptor (TCR)-mediated recognition of metabolites derived from the vitamin B2 biosynthetic pathway.…”

Section: Microbe-immune System Interactions On the Skinmentioning

confidence: 99%

Mechanisms of microbe-immune system dialogue within the skin

Lunjani

¹

,

Ahearn-Ford

²

,

Dube

³

et al. 2021

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The prevalence and severity of dermatological conditions such as atopic dermatitis have increased dramatically during recent decades. Many of the factors associated with an altered risk of developing inflammatory skin disorders have also been shown to alter the composition and diversity of non-pathogenic microbial communities that inhabit the human host. While the most densely microbial populated organ is the gut, culture and non-culture-based technologies have revealed a dynamic community of bacteria, fungi, viruses and mites that exist on healthy human skin, which change during disease. In this review, we highlight some of the recent findings on the mechanisms through which microbes interact with each other on the skin and the signalling systems that mediate communication between the immune system and skin-associated microbes. In addition, we summarize the ongoing clinical studies that are targeting the microbiome in patients with skin disorders. While significant efforts are still required to decipher the mechanisms underpinning host-microbe communication relevant to skin health, it is likely that disease-related microbial communities, or Dermatypes, will help identify personalized treatments and appropriate microbial reconstitution strategies.

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“…Once established, balanced immunological interactions enable symbiotic relationships with the microbiota in adult life. This process has been extensively investigated in the mammalian epithelial monolayer epithelium-covered intestine and lung mucosae [40][41][42][43]; however, the mechanisms utilized by the oral mucosa to establish homeostasis are unclear [1]. In addition, ageing of the immune system (immunosenescence) combined with a low-grade inflammation that develops during ageing (inflammaging) is thought to impact the outcomes of the oral disease challenge from the microbiota [31,44].…”

Section: Introductionmentioning

confidence: 99%

The niche-specialist and age-related oral microbial ecosystem: crosstalk with host immune cells in homeostasis

Lin

¹

,

Hu

²

,

Yang

³

et al. 2022

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Although characterization of the baseline oral microbiota has been discussed, the current literature seems insufficient to draw a definitive conclusion on the interactions between the microbes themselves or with the host. This study focuses on the spatial and temporal characteristics of the oral microbial ecosystem in a mouse model and its crosstalk with host immune cells in homeostasis. The V3V4 regions of the 16S rRNA gene of 20 samples from four niches (tongue, buccal mucosa, keratinized gingiva and hard palate) and 10 samples from two life stages (adult and old) were analysed. Flow cytometry (FCM) was used to investigate the resident immune cells. The niche-specialist and age-related communities, characterized based on the microbiota structure, interspecies communications, microbial functions and interactions with immune cells, were addressed. The phylum Firmicutes was the major component in the oral community. The microbial community profiles at the genus level showed that the relative abundances of the genera Bacteroides , Lactobacillus and Porphyromonas were enriched in the gingiva. The abundance of the genera Streptococcus , Faecalibaculum and Veillonella was increased in palatal samples, while the abundance of Neisseria and Bradyrhizobium was enriched in buccal samples. The genera Corynebacterium , Stenotrophomonas, Streptococcus and Fusobacterium were proportionally enriched in old samples, while Prevotella and Lacobacillus were enriched in adult samples. Network analysis showed that the genus Lactobacillus performed as a central node in the buccal module, while in the gingiva module, the central nodes were Nesterenkonia and Hydrogenophilus . FCM showed that the proportion of Th1 cells in the tongue samples (38.18 % [27.03–49.34 %]) (mean [range]) was the highest. The proportion of γδT cells in the buccal mucosa (25.82 % [22.1–29.54 %]) and gingiva (20.42 % [18.31–22.53 %]) samples was higher (P<0.01) than those in the palate (14.18 % [11.69–16.67 %]) and tongue (9.38 % [5.38–13.37 %] samples. The proportion of Th2 (31.3 % [16.16–46.44 %]), Th17 (27.06 % [15.76–38.36 %]) and Treg (29.74 % [15.71–43.77 %]) cells in the old samples was higher than that in the adult samples (P<0.01). Further analysis of the interplays between the microbiomes and immune cells indicated that Th1 cells in the adult group, nd Th2, Th17 and Treg cells in the old group were the main immune factors strongly associated with the oral microbiota. For example, Th2, Th17 and Treg cells showed a significantly positive correlation with age-related microorganisms such as Sphingomonas , Streptococcus and Acinetobacter , while Th1 cells showed a negative correlation. Another positive correlation occurred between Th1 cells and several commensal microbiomes such as Lactobacillus , Jeotgalicoccus and Sporosarcina . Th2, Th17 and Treg cells showed the opposite trend. Together, our findings identify the niche-specialist and age-related characteristics of the oral microbial ecosystem and the potential associations between the microbiomes and the mucosal immune cells, providing critical insights into mucosal microbiology.

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“…Blood MAIT cell frequency is modified during several auto-immune diseases, which are often associated with microbiota dysbiosis (see below), emphasizing the interaction between MAIT cells and the microbiota [ 10 ]. In fact, MAIT cells can perceive microbial stress due to changes in riboflavin utilization in various microbial communities.…”

Section: The Role Of the Microbiota In Shaping Mait Cellsmentioning

confidence: 99%

MAIT Cells and Microbiota in Multiple Sclerosis and Other Autoimmune Diseases

Mechelli

¹

,

Romano

²

,

Romano

³

et al. 2021

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The functions of mucosal-associated invariant T (MAIT) cells in homeostatic conditions include the interaction with the microbiota and its products, the protection of body barriers, and the mounting of a tissue-repair response to injuries or infections. Dysfunction of MAIT cells and dysbiosis occur in common chronic diseases of inflammatory, metabolic, and tumor nature. This review is aimed at analyzing the changes of MAIT cells, as well as of the microbiota, in multiple sclerosis and other autoimmune disorders. Common features of dysbiosis in these conditions are the reduced richness of microbial species and the unbalance between pro-inflammatory and immune regulatory components of the gut microbiota. The literature concerning MAIT cells in these disorders is rather complex, and sometimes not consistent. In multiple sclerosis and other autoimmune conditions, several studies have been done, or are in progress, to find correlations between intestinal permeability, dysbiosis, MAIT cell responses, and clinical biomarkers in treated and treatment-naïve patients. The final aims are to explain what activates MAIT cells in diseases not primarily infective, which interactions with the microbiota are potentially pathogenic, and their dynamics related to disease course and disease-modifying treatments.

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The dialogue between unconventional T cells and the microbiota

Cited by 19 publications

References 175 publications

Mechanisms of microbe-immune system dialogue within the skin

Mechanisms of microbe-immune system dialogue within the skin

The niche-specialist and age-related oral microbial ecosystem: crosstalk with host immune cells in homeostasis

MAIT Cells and Microbiota in Multiple Sclerosis and Other Autoimmune Diseases

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