DTR‐mediated conditional cell ablation—Progress and challenges

Cell ablation is a valuable complement to mutagenesis for experimentally defining specific cell functions in physiology and pathophysiology in small animal models. One of the most popular ablation strategies involves transgenic expression of a primate diphtheria toxin receptor (DTR) on murine cells that are otherwise resistant to the bacterial exotoxin. The efforts of many laboratories using the DTR approach over the years have yielded numerous valuable insights into specific cell functions. Here, we will discuss the technical aspects of the DTR approach, including the strengths, pitfalls, and future strategies to overcome the shortcomings, highlighting a recent paper published in the European Journal of Immunology [El Hachem et al. Eur. J. Immunol. 2018 https://doi.org/10.1002/eji.201747351 ]. A particular focus will be given to the application of DTR approach to decipher in vivo functions of the murine myeloid cell compartment.     

Transient ablation of alveolar macrophages leads to massive pathology of influenza infection without affecting cellular adaptive immunity

Alveolar macrophages (AMs), localized at the pulmonary air‐tissue interface, are one of the first lines of defense that interact with inhaled airborne pathogens such as influenza viruses. By using a new CD169‐DTR transgenic mouse strain we demonstrate that specific and highly controlled in vivo ablation of this myeloid cell subset leads to severe impairment of the innate, but not adaptive, immune responses and critically affects the progression of the disease. In fact, AM‐ablated mice, infected with a normally sublethal dose of PR8 influenza virus, showed dramatically increased virus load in the lungs, severe airway inflammation, pulmonary edema and vascular leakage, which caused the death of the infected animals. Our data highlight the possibilities for new therapeutic strategies focusing on modulation of AMs, which may efficiently boost innate responses to influenza infections.     

Physical activity and sitting time prior to and during COVID-19 lockdown in Austrian high-school students

The COVID-19 pandemic has led in many countries to the implementation of policies that mandate social distancing and movement restrictions. While these measures are warranted in order to minimize the spread of the virus they may have detrimental effects on various behaviors, including physical activity (PA). The present study examined PA and sitting time in 14 to18-year-old Austrian high school students prior to and during the second COVID-19 lockdown in Austria. Data was collected via an online questionnaire during fall/winter 2020/21. Questions were based on the International Physical Activity Questionnaire, which examined frequency and duration of PA and sitting time. A total of 221 high school students provided valid data. Participants reported significantly lower moderate and vigorous PA during the lockdown while sitting time increased (p < 0.01). The frequency of walking (days/week) also decreased during COVID-19 lockdown, which also contributed to a significant decline in total walking time (p < 0.01). Further, the decline in PA was more pronounced in boys, while girls reported a greater decline in walking. These differences were due to higher PA and walking in boys and girls, respectively, prior to the lockdown. During the lockdown sex differences in PA and sitting time were limited. Taken together, these results highlight the impact of COVID-19 policies on PA in adolescents and emphasize the importance to promote an active lifestyle even in times of home confinement.     

Attitudes of winter sport participants toward ski helmet mandatory

The aim of this study was to examine attitudes of winter sport participants toward a ski helmet mandatory. In total, 959 persons who had to estimate statements regarding ski helmet and helmet mandatory with the aid of a five level Likert scale were interviewed. About 85?% of interviewed persons totally agreed that a ski helmet reduces head injury risk although only 64?% are wearing a ski helmet. Significant more helmet wearers and females compared to non-wearers and males totally agreed that all winter sport participants should wear ski helmets on slopes as well as that all children on slopes should wear a ski helmet. Also, significant more helmet wearers and females compared to non-wearers and males totally agreed that a ski helmet mandatory for all people has to be recommended as well as that a ski helmet mandatory for children under 16 years has to be recommended. However, the acceptance for a helmet mandatory for all people as well as for children was significantly lower compared to recommendations for helmet use irrespective of helmet use or gender. Therefore, we conclude that preventive helmet campaigns possibly attain a higher acceptance leading to a higher helmet use compared to a helmet mandatory.