Graphical Abstract Highlights d T lymphocytes release exosomes containing specific microRNAs d T lymphocyte exosomes can transfer microRNAs to rodent and human pancreatic b cells d The transferred microRNAs trigger chemokine expression and apoptosis of b cells d Blockade of microRNAs transferred in b cells decreases diabetes incidence in NOD mice In Brief Guay et al. show that T cells release exosomes containing specific microRNAs that trigger chemokine expression and apoptosis in recipient pancreatic b cells in type 1 diabetes. Inactivation of miR-142-3p/-5p and miR-155 in b cells results in higher insulin levels, lower insulitis scores, and reduced inflammation and protects NOD mice from diabetes development.

The Dutch Threatening Medical Situations Inventory (TM%) has been developed to measure cognitive confrontation ('monitoring') and cognitive avoidance ('blunting') within the domain of medical threat. It consists of four scenarios of threatening medical situations. followed by monitoring and blunting alternatives. Its psychometric properties are investigated in students (IV = 123) dental (IV = 80). HIV-(N = 42) and surgery patients (N = 123). For both scales, internal consistencies proved to be satisfactory. Slight sex and age effects are found. Furthermore, there is a strong situation effect: the scenario highest in controllability shows relatively high monitoring and low blunting scores. Factor structure is stable across samples and shows a good fit with the predicted factor solution. Both scales are found to converge and diverge in a theoretically meaningful manner with a variety of coping style and anxiety measures. In two samples, a sample specific stress scenario was added. but the psychometric qualities of such an extension should not be taken for granted. In an additional sample of working people (N = 48) test-retest reliability proved to be good. It is concluded that the TMSI is a useful instrument for assessmg cognitive confrontation and avoidance in medical patients. An English as well as a German translation are available.

Bile acids (BAs) facilitate intestinal absorption of lipid-soluble nutrients and modulate various metabolic pathways through the farnesoid X receptor (FXR) and Takeda G-protein-coupled receptor 5. These receptors are targets for therapy in cholestatic and metabolic diseases. However, dissimilarities in BA metabolism between humans and mice complicate translation of preclinical data. Cytochrome P450 family 2 subfamily c polypeptide 70 (CYP2C70) was recently proposed to catalyze the formation of rodent-specific muricholic acids (MCAs). With CRISPR/Cas9-mediated somatic genome editing, we generated an acute hepatic Cyp2c70 knockout mouse model (Cyp2c70ako) to clarify the role of CYP2C70 in BA metabolism in vivo and evaluate whether its activity modulates effects of pharmacologic FXR activation on cholesterol homeostasis. In Cyp2c70ako mice, chenodeoxycholic acid (CDCA) increased at the expense of βMCA, resulting in a more hydrophobic human-like BA pool. Tracer studies demonstrated that, in vivo, CYP2C70 catalyzes the formation of βMCA primarily by sequential 6β-hydroxylation and C7-epimerization of CDCA, generating αMCA as an intermediate metabolite. Physiologically, the humanized BA composition in Cyp2c70ako mice blunted the stimulation of fecal cholesterol disposal in response to FXR activation compared with WT mice, predominantly due to reduced stimulation of transintestinal cholesterol excretion. Thus, deletion of hepatic Cyp2c70 in adult mice translates into a human-like BA pool composition and impacts the response to pharmacologic FXR activation. This Cyp2c70ako mouse model may be a useful tool for future studies of BA signaling and metabolism that informs human disease development and treatment.

Background and Aims Bile acids (BAs) aid intestinal fat absorption and exert systemic actions by receptor-mediated signaling. BA receptors have been identified as drug targets for liver diseases. Yet, differences in BA metabolism between humans and mice hamper translation of pre-clinical outcomes. Cyp2c70 -ablation in mice prevents synthesis of mouse/rat-specific muricholic acids (MCAs), but potential (patho)physiological consequences of their absence are unknown. We therefore assessed age- and gender-dependent effects of Cyp2c70 -deficiency in mice. Methods The consequences of Cyp2c70 -deficiency were assessed in male and female mice at different ages. Results Cyp2c70 -/- mice were devoid of MCAs and showed high abundances of chenodeoxycholic and lithocholic acids. Cyp2c70 -deficiency profoundly impacted microbiome composition. Bile flow and biliary BA secretion were normal in Cyp2c70 -/- mice of both sexes. Yet, the pathophysiological consequences of Cyp2c70 -deficiency differed considerably between sexes. Three-week old male Cyp2c70 -/- mice showed high plasma BAs and transaminases, which spontaneously decreased thereafter to near-normal levels. Only mild ductular reactions were observed in male Cyp2c70 -/- mice up to 8 months of age. In female Cyp2c70 -/- mice, plasma BAs and transaminases remained substantially elevated with age, gut barrier function was impaired and bridging fibrosis was observed at advanced age. Addition of 0.1% ursodeoxycholic acid to the diet fully normalized hepatic and intestinal functions in female Cyp2c70 -/- mice. Conclusion Cyp2c70 -/- mice show transient neonatal cholestasis and develop cholangiopathic features that progress to bridging fibrosis in females only. These consequences of Cyp2c70 -deficiency are restored by treatment with UDCA, indicating a role of BA hydrophobicity in disease development.

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Fourteen genes encoding putative secondary amino acid transporters were identified in the genomes of Lactococcus lactis subsp. cremoris strains MG1363 and SK11 and L. lactis subsp. lactis strains IL1403 and KF147, 12 of which were common to all four strains. Amino acid uptake in L. lactis cells overexpressing the genes revealed transporters specific for histidine, lysine, arginine, agmatine, putrescine, aromatic amino acids, acidic amino acids, serine, and branched-chain amino acids. Substrate specificities were demonstrated by inhibition profiles determined in the presence of excesses of the other amino acids. Four knockout mutants, lacking the lysine transporter LysP, the histidine transporter HisP (formerly LysQ), the acidic amino acid transporter AcaP (YlcA), or the aromatic amino acid transporter FywP (YsjA), were constructed. The LysP, HisP, and FywP deletion mutants showed drastically decreased rates of uptake of the corresponding substrates at low concentrations. The same was observed for the AcaP mutant with aspartate but not with glutamate. In rich M17 medium, the deletion of none of the transporters affected growth. In contrast, the deletion of the HisP, AcaP, and FywP transporters did affect growth in a defined medium with free amino acids as the sole amino acid source. HisP was essential at low histidine concentrations, and AcaP was essential in the absence of glutamine. FywP appeared to play a role in retaining intracellularly synthesized aromatic amino acids when these were not added to the medium. Finally, HisP, AcaP, and FywP did not play a role in the excretion of accumulated histidine, glutamate, or phenylalanine, respectively, indicating the involvement of other transporters.

SummaryPyruvoyl-dependent histidine decarboxylases are produced as proenzymes that mature by cleavage followed by formation of the pyruvoyl prosthetic group. The histidine decarboxylation pathway of Streptococcus thermophilus CHCC1524 that consists of the pyruvoyl-dependent histidine decarboxylase HdcA and the histidine/histamine exchanger HdcP was functionally expressed in Lactococcus lactis. The operon encoding the pathway contains in addition to the hdcA and hdcP genes a third gene hdcB. Expression of different combinations of the genes in L. lactis and Escherichia coli followed by analysis of the protein products demonstrated the involvement of HdcB in the cleavage of the HdcA proenzyme. The HdcA proenzyme and HdcB protein were purified to homogeneity and cleavage and activation of the histidine decarboxylase activity was demonstrated in vitro. Substoichiometric amounts of HdcB were required to cleave HdcA showing that HdcB functions as an enzyme. In agreement, expression levels of HdcB in the cells were low relative to those of HdcA. The turnover number of HdcB in vitro was extremely low (0.05 min -1 ) which was due to a very slow association/dissociation of the enzyme/substrate complex. In fact, HdcB was shown to co-purify both with the HdcA S82A mutant that mimics the proenzyme and with the mature HdcA complex.

A multiplex PCR method, aimed at the detection of genes associated with biogenic amine production, identified the odc gene encoding ornithine decarboxylase in 1 of 15 strains of Staphylococcus epidermidis. The ability of the positive strain, S. epidermidis 2015B, to produce putrescine in vitro was demonstrated by high-performance liquid chromatography (HPLC). In this strain, the odc gene was detected on plasmid DNA, suggesting that the ability to form putrescine is carried by a mobile element, which explains the fact that the trait is strain dependent within the S. epidermidis species. A 6,292-bp nucleotide sequence harboring the putative odc gene was determined. S. epidermidis ornithine decarboxylase (ODC) showed 60 to 65% sequence identity with known ODCs of Gram-positive as well as Gram-negative bacteria. Downstream of the odc gene, a gene encoding a putative amino acid transporter was found that shared 59% sequence identity with the ornithine/putrescine exchanger (PotE) of Escherichia coli. Cloning and expression of the potE gene of S. epidermis 2015B in Lactococcus lactis demonstrated that the gene product transported ornithine and putrescine into the cells and efficiently exchanged putrescine for ornithine. Analysis of the flanking regions showed high identity levels with different S. epidermidis plasmid sequences, which would confirm the plasmidic location of the odc operon. It follows that the odc and potE gene pair encodes a putrescine-producing pathway in S. epidermis 2015B that was acquired through horizontal gene transfer.