TSLP AhR IAId Tryptophan Epidermis Dermis AhRE TSLP IL-4,IL-5,IL-13,IL-22AD Background: Previous studies have revealed significant alterations in the skin microbiota of patients with atopic dermatitis (AD) not only in diversity and composition but also in function, and the tryptophan (Trp) metabolic pathway is attenuated in the skin microbiota of patients with AD. Objective: We sought to assess Trp metabolites on the skin surfaces of patients with AD and to explore the function of the microbial Trp metabolites in skin inflammation in patients with AD.Methods: A gel-patch method was developed to collect metabolites on the skin surface, which were then assessed by using liquid chromatography-tandem mass spectrometry. A mouse model of calcipotriol (MC903)-induced AD-like dermatitis was used to evaluate the effects of microbial metabolites on AD, and aryl hydrocarbon receptor (AhR)-null mice and keratinocyte cultures were used to investigate the mechanism.We thank Professor Shau-Ku Huang for helpful suggestions and reviewing the manuscript. Key messagesd Levels of microbial metabolites of Trp metabolism on skin surfaces of patients with AD were lower than those of healthy subjects.d IAId significantly attenuated skin inflammation in a mouse model of MC903-induced AD-like dermatitis.d IAId inhibited TSLP expression in keratinocytes in an AhR-dependent manner.

Accumulating evidence indicates that metabolism reprogramming is critically important to T cell differentiation, and manipulating metabolic pathways in T cells can shape their fate and function. During T cell differentiation, metabolism provides T cells with energy as well as precursors for various biological processes. Some key metabolic reactions, such as glycolysis, oxidative phosphorylation and fatty acid oxidation, are also considered to play important roles in T cell activation and differentiation. In this review, we will explain why cellular metabolism is important for the Th17/T-regulatory (Treg) cell balance and how metabolism reprogramming impacts this balance. Moreover, we will also discuss some important metabolic sensors, such as mammalian target of rapamycin, AMP-activated protein kinase, and some nuclear receptors. In addition, we will review specific small molecular compounds, which can shift the Th17/Treg cell balance and, therefore, have promising therapeutic roles. Finally, potential methods of manipulating Th17 cell metabolism for treating Th17-associated diseases will be discussed.

PTPRE-AS1 deficiency aggravates pulmonary inflammation but reduces colitis severity by modulating M2 macrophage activation.

Background: Epidemiologic evidence suggests that exposure to particulate matter of 2.5 mm or less in diameter (PM2.5) aggravates asthma. Objective: We sought to investigate the underlying mechanisms between PM2.5 exposure and asthma severity. Methods: The relationship between PM2.5 exposure and asthma severity was investigated in an asthma model with CD4 1 T cellspecific aryl hydrocarbon receptor (AhR)-null mice. Effects of PM2.5 and polycyclic aromatic hydrocarbons (PAHs) on differentiation of T H 17/regulatory T (Treg) cells were investigated by using flow cytometry and quantitative RT-PCR. Mechanisms were investigated by using mRNA sequencing, chromatin immunoprecipitation, bisulfite sequencing, and glycolysis rates. Results: PM2.5 impaired differentiation of Treg cells, promoted differentiation of T H 17 cells, and aggravated asthma in an AhRdependent manner. PM2.5 and one of its prominent PAHs, indeno[1,2,3-cd]pyrene (IP), promoted differentiation of T H 17 cells by upregulating hypoxia-inducible factor 1a expression and enhancing glycolysis through AhRs. Exposure to PM2.5 and IP enhanced glutamate oxaloacetate transaminase 1 (Got1) expression through AhRs and accumulation of 2-hydroxyglutarate, which inhibited ten-eleven translocation methylcytosine dioxygenase 2 activity, resulting in hypermethylation in the forkhead box P3 locus and impaired differentiation of Treg cells. A GOT1 inhibitor, (aminooxy)acetic acid, ameliorated asthma by shifting differentiation of T H 17 cells to Treg cells. Similar regulatory effects of exposure to PM2.5 or IP on T H 17/Treg cell imbalance were noted in human T cells, and in a case-control design PAH exposure appeared to be a potential risk factor for asthma. Conclusions: The AhR-hypoxia-inducible factor 1a and AhR-GOT1 molecular pathways mediate pulmonary responses on exposure to PM2.5 through their ability to disturb the balance of T H 17/Treg cells.

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