Natural agonists for aryl hydrocarbon receptor in culture medium are essential for optimal differentiation of Th17 T cells

Th17 cell differentiation is dependent on interleukin (IL)-6 and transforming growth factor (TGF)-β, and it is modulated by activation of the aryl hydrocarbon receptor (AhR). In this study, we show that differentiation of Th17 cells, but not Th1 or induced regulatory T (iT reg) cells, is increased by endogenous AhR agonists present in culture medium. Th17 development from wild-type mice is suboptimal in the presence of the AhR antagonist CH-223191, similar to the situation in AhR-deficient mice, which show attenuated IL-17 production and no IL-22 production. The presence of natural AhR agonists in culture medium is also revealed by the induction of CYP1A1, a downstream target of AhR activation. However, the most commonly used medium, RPMI, supports very low levels of Th17 polarization, whereas Iscove's modified Dulbecco's medium, a medium richer in aromatic amino acids, which give rise to AhR agonists, consistently results in higher Th17 expansion in both mouse and human cells. The relative paucity of AhR agonists in RPMI medium, coupled with the presence of factors conducive to IL-2 activation and enhanced Stat5 phosphorylation, conspire against optimal Th17 differentiation. Our data emphasize that AhR activation plays an essential part in the development of Th17 cells and provide a rational explanation for the poor in vitro polarization of Th17 cells that is reported in the majority of publications for both mouse and human cells

Glutathione S-transferase activity during pregnancy in the mouse: effects of trans-stilbene oxide pretreatment

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24665/1/0000078.pd

Influence of genetic factors on toluene diisocyanate-related symptoms: evidence from a cross-sectional study

Background: Toluene diisocyanate (TDI) is a highly reactive compound used in the production of, e. g., polyurethane foams and paints. TDI is known to cause respiratory symptoms and diseases. Because TDI causes symptoms in only a fraction of exposed workers, genetic factors may play a key role in disease susceptibility. Methods: Workers (N = 132) exposed to TDI and a non-exposed group ( N = 114) were analyzed for genotype (metabolising genes: CYP1A1*2A, CYP1A1*2B, GSTM1*O, GSTM3*B, GSTP1 1105V, GSTP1 A114V, GSTT1*O, MPO -463, NAT1*3, *4, *10, *11, *14, *15, NAT2*5, *6, *7, SULT1A1 R213H; immune-related genes: CCL5 -403, HLA-DQB1* 05, TNF-308, TNF-863) and symptoms of the eyes, upper and lower airways ( based on structured interviews). Results: For three polymorphisms: CYP1A1*2A, CYP1A1*2B, and TNF -308 there was a pattern consistent with interaction between genotype and TDI exposure status for the majority of symptoms investigated, although it did reach statistical significance only for some symptoms: among TDI-exposed workers, the CYP1A1 variant carriers had increased risk (CYP1A1*2A and eye symptoms: variant carriers OR 2.0 95% CI 0.68-6.1, p-value for interaction 0.048; CYP1A1*2B and wheeze: IV carriers OR = 12, 1.4-110, p-value for interaction 0.057). TDI-exposed individuals with TNF-308 A were protected against the majority of symptoms, but it did not reach statistical significance. In the non-exposed group, however, TNF -308 A carriers showed higher risk of the majority of symptoms ( eye symptoms: variant carriers OR = 2.8, 1.1-7.1, p-value for interaction 0.12; dry cough OR = 2.2, 0.69-7.2, p-value for interaction 0.036). Individuals with SULT1A1 213H had reduced risk both in the exposed and non-exposed groups. Other polymorphisms, showed associations to certain symptoms: among TDI-exposed, NAT1*10 carriers had a higher risk of eye symptoms and CCL5 -403 AG+AA as well as HLA-DQB1 *05 carriers displayed increased risk of symptoms of the lower airways. GSTM1, GSTM3 and GSTP1 only displayed effects on symptoms of the lower airways in the non-exposed group. Conclusion: Specific gene-TDI interactions for symptoms of the eyes and lower airways appear to exist. The results suggest different mechanisms for TDI- and non- TDI-related symptoms of the eyes and lower airways

4-(4-nitrobenzyl)pyridine tests for alkylating agents following chemical oxidative activation

A chemical activation system (CAS) designed to mimic the mammalian mixed-function oxidase enzymes was found to activate target compounds to reactive electrophiles. Activated compounds were assayed by reaction with 4-(4-nitrobenzyl)pyridine (NBP). A model nucleophile of 7-alkylguanine of nucleic acids, NBP produces a violet color following alkylation. Twenty compounds from several chemical classes were tested. The test generally gave positive and negative responses where expected. Two compounds, trichloroethylene and diethylnitrosamine, exhibited a linear Beer's law relationship in the concentration range tested. A high degree of linear correlation (r>0.97) was obtained for these compounds. Other compounds showed varying degrees of linear correlation from high correlation (r=0.94) to weak correlation (r=0.44). The CAS-NBP assay results were compared to bacterial mutagenicity and animal carcinogenicity test results when information was available. A good correlation (r=0.80) existed between direct alkylating activity and direct mutagenicity. Similar correlations existed between NBP alkylation following activation and mutagenicity following microsomal activation (r=0.73). Also, different correlations were observed between carcinogenicity and NBP alkylation following activation (r=0.69) and without activation (r=0.38).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48076/1/244_2004_Article_BF00213289.pd

Controlling Viral Immuno-Inflammatory Lesions by Modulating Aryl Hydrocarbon Receptor Signaling

Ocular herpes simplex virus infection can cause a blinding CD4+ T cell orchestrated immuno-inflammatory lesion in the cornea called Stromal Keratitis (SK). A key to controlling the severity of SK lesions is to suppress the activity of T cells that orchestrate lesions and enhance the representation of regulatory cells that inhibit effector cell function. In this report we show that a single administration of TCDD (2, 3, 7, 8- Tetrachlorodibenzo-p-dioxin), a non-physiological ligand for the AhR receptor, was an effective means of reducing the severity of SK lesions. It acted by causing apoptosis of Foxp3- CD4+ T cells but had no effect on Foxp3+ CD4+ Tregs. TCDD also decreased the proliferation of Foxp3- CD4+ T cells. The consequence was an increase in the ratio of Tregs to T effectors which likely accounted for the reduced inflammatory responses. In addition, in vitro studies revealed that TCDD addition to anti-CD3/CD28 stimulated naïve CD4+ T cells caused a significant induction of Tregs, but inhibited the differentiation of Th1 and Th17 cells. Since a single TCDD administration given after the disease process had been initiated generated long lasting anti-inflammatory effects, the approach holds promise as a therapeutic means of controlling virus induced inflammatory lesions