Heme oxygenase-1 drives metaflammation and insulin resistance in mouse and man.

Obesity and diabetes affect more than half a billion individuals worldwide. Interestingly, the two conditions do not always coincide and the molecular determinants of "healthy" versus "unhealthy" obesity remain ill-defined. Chronic metabolic inflammation (metaflammation) is believed to be pivotal. Here, we tested a hypothesized anti-inflammatory role for heme oxygenase-1 (HO-1) in the development of metabolic disease. Surprisingly, in matched biopsies from "healthy" versus insulin-resistant obese subjects we find HO-1 to be among the strongest positive predictors of metabolic disease in humans. We find that hepatocyte and macrophage conditional HO-1 deletion in mice evokes resistance to diet-induced insulin resistance and inflammation, dramatically reducing secondary disease such as steatosis and liver toxicity. Intriguingly, cellular assays show that HO-1 defines prestimulation thresholds for inflammatory skewing and NF-κB amplification in macrophages and for insulin signaling in hepatocytes. These findings identify HO-1 inhibition as a potential therapeutic strategy for metabolic disease.

Current mentorship practices in the training of the next generation of clinical microbiology and infectious disease specialists: an international cross-sectional survey.

The purpose of this study was to describe the current practice of mentorship in clinical microbiology (CM) and infectious diseases (ID) training, to identify possible areas for improvement and to assess the factors that are associated with satisfactory mentorship. An international cross-sectional survey containing 35 questions was answered by 317 trainees or specialists who recently completed clinical training. Overall, 179/317 (56%) trainees were satisfied with their mentors, ranging from 7/9 (78%) in non-European countries, 39/53 (74%) in Northern Europe, 13/22 (59%) in Eastern Europe, 61/110 (56%) in Western Europe, 37/76 (49%) in South-Western Europe to 22/47 (47%) in South-Eastern Europe. However, only 115/317 (36%) respondents stated that they were assigned an official mentor during their training. In multivariable logistic regression analysis, the satisfaction of trainees was significantly associated with having a mentor who was a career model (OR 6.4, 95%CI 3.5-11.7), gave constructive feedback on work performance (OR 3.3, 95%CI 1.8-6.2), and knew the family structure of the mentee (OR 5.5, 95%CI 3.0-10.1). If trainees felt overburdened, 70/317 (22%) felt that they could not talk to their mentors. Moreover, 67/317 (21%) stated that they could not talk to their mentor when unfairly treated and 59/317 (19%) felt uncertain. Training boards and authorities responsible for developing and monitoring CM&ID training programmes should invest in the development of high-quality mentorship programmes for trainees in order to contribute to the careers of the next generation of professionals.

How are trainees in clinical microbiology and infectious diseases supervised in Europe? An international cross-sectional questionnaire survey by the Trainee Association of ESCMID.

The purpose of this study was to map the supervision of European trainees in clinical microbiology and infectious diseases during their training. An international cross-sectional questionnaire survey of 38 questions was distributed among trainees and recently graduated medical specialists from European countries. Descriptive analyses were performed on both the total group of respondents and regionally. In total, 393 respondents from 37 different countries were included. The median of overall satisfaction with the supervisor was 4 (interquartile range 3-4) on a Likert scale (range 1, not satisfied at all-5, completely satisfied). Overall, merely 34% of respondents received constructive feedback from their supervisor on a regularly basis, 36% could evaluate their own supervisor, and just 63% were evaluated on their skills using a written plan. Fifty-two percent did not receive the opportunity to do a part of the specialty training abroad and 63% received support from their supervisors to be involved in research projects or publishing papers. A considerable proportion of trainees, mainly in Southern and Eastern European regions, felt that they did not receive sufficient supervision. This information may be useful in the pursuit of harmonizing the quality of training, achieving a common curriculum, and identifying robust and objective criteria to coach and evaluate trainees in a proper way.

Mast cells have no impact on cutaneous leishmaniasis severity and related Th2 differentiation in resistant and susceptible mice.

The genus leishmania comprises different protozoan parasites which are causative agents of muco-cutaneous and systemic, potentially lethal diseases. After infection with the species Leishmania major, resistant mice expand Th1 cells which stimulate macrophages for Leishmania destruction. In contrast, susceptible mice generate Th2 cells which deactivate macrophages, leading to systemic spread of the pathogens. Th-cell differentiation is determined within the first days, and Th2 cell differentiation requires IL-4, whereby the initial IL-4 source is often unknown. Mast cells are potential sources of IL-4, and hence their role in murine leishmaniasis has previously been studied in mast cell-deficient Kit mutant mice, although these mice display immunological phenotypes beyond mast cell deficiency. We therefore readdressed this question by infecting Kit-independent mast cell-deficient mice that are Th1 (C57BL/6 Cpa(Cre) ) or Th2 (BALB/c Cpa(Cre) ) prone with L. major. Using different parasite doses and intra- or subcutaneous infection routes, the results demonstrate no role of mast cells on lesion size development, parasite load, immune cell phenotypes expanding in draining lymph nodes, and cytokine production during murine cutaneous leishmaniasis. Thus, other cell types such as ILCs or T cells have to be considered as primary source of Th2-driving IL-4.

HO-1 inhibits preadipocyte proliferation and differentiation at the onset of obesity via ROS dependent activation of Akt2.

Excessive accumulation of white adipose tissue (WAT) is a hallmark of obesity. The expansion of WAT in obesity involves proliferation and differentiation of adipose precursors, however, the underlying molecular mechanisms remain unclear. Here, we used an unbiased transcriptomics approach to identify the earliest molecular underpinnings occuring in adipose precursors following a brief HFD in mice. Our analysis identifies Heme Oxygenase-1 (HO-1) as strongly and selectively being upregulated in the adipose precursor fraction of WAT, upon high-fat diet (HFD) feeding. Specific deletion of HO-1 in adipose precursors of Hmox1fl/flPdgfraCre mice enhanced HFD-dependent visceral adipose precursor proliferation and differentiation. Mechanistically, HO-1 reduces HFD-induced AKT2 phosphorylation via ROS thresholding in mitochondria to reduce visceral adipose precursor proliferation. HO-1 influences adipogenesis in a cell-autonomous way by regulating events early in adipogenesis, during the process of mitotic clonal expansion, upstream of Cebpα and PPARγ. Similar effects on human preadipocyte proliferation and differentiation in vitro were observed upon modulation of HO-1 expression. This collectively renders HO-1 as an essential factor linking extrinsic factors (HFD) with inhibition of specific downstream molecular mediators (ROS &AKT2), resulting in diminished adipogenesis that may contribute to hyperplastic adipose tissue expansion.