An NFkB activity calculator to delineate signaling crosstalk: type I and II interferons enhance NFkB via distinct mechanisms

Nuclear factor kappa B (NFκB) is a transcription factor that controls inflammation and cell survival. In clinical histology, elevated NFκB activity is a hallmark of poor prognosis in inflammatory disease and cancer, and may be the result of a combination of diverse micro-environmental constituents. While previous quantitative studies of NFκB focused on its signaling dynamics in single cells, we address here how multiple stimuli may combine to control tissue level NFκB activity. We present a novel, simplified model of NFκB (SiMoN) that functions as an NFκB activity calculator. We demonstrate its utility by exploring how type I and type II interferons modulate NFκB activity in macrophages. Whereas, type I IFNs potentiate NFκB activity by inhibiting translation of IκBα and by elevating viral RNA sensor (RIG-I) expression, type II IFN amplifies NFκB activity by increasing the degradation of free IκB through transcriptional induction of proteasomal cap components (PA28). Both cross-regulatory mechanisms amplify NFκB activation in response to weaker (viral) inducers, while responses to stronger (bacterial or cytokine) inducers remain largely unaffected. Our work demonstrates how the NFκB calculator can reveal distinct mechanisms of crosstalk on NFκB activity in interferon-containing microenvironments

Surface-charge-induced orientation of interfacial water suppresses heterogeneous ice nucleation on α-alumina (0001)

Surface charge is one of the surface properties of atmospheric aerosols, which has been linked to heterogeneous ice nucleation and hence cloud formation, microphysics, and optical properties. Despite the importance of surface charge for ice nucleation, many questions remain on the molecular-level mechanisms at work. Here, we combine droplet-freezing assay studies with vibrational sum frequency generation (SFG) spectroscopy to correlate interfacial water structure to surface nucleation strength. We study immersion freezing of aqueous solutions of various pHs on the atmospherically relevant aluminum oxide α-Al2O3 (0001) surface using an isolated droplet on the surface. The high-pH solutions freeze at temperatures higher than that of the low-pH solution, while the neutral pH has the highest freezing temperature. On the molecular level, the SFG spectrum of the interfacial water changes substantially upon freezing. At all pHs, crystallization leads to a reduction of intensity of the 3400 cm−1 water resonance, while the 3200 cm−1 intensity drops for low pH but increases for neutral and high pHs. We find that charge-induced surface templating suppresses nucleation, irrespective of the sign of the surface charge. Heterogeneous nucleation is most efficient for the nominally neutral surface

New Insights Into the Initiation of Atrial Fibrillation

Background— This study investigated onset scenarios of atrial fibrillation (AF), the first phase of the Atrial Fibrillation Therapy (AFT) trial, to determine potential arrhythmogenic triggers as targets for atrial pacing algorithms that have been proposed for prevention of AF. Methods and Results— Ninety-eight patients (58 men; age 65±11 years) with recurrent, symptomatic, drug-refractory AF and a conventional pacemaker indication in 31 of 98 received a dual-chamber pacemaker. Using novel diagnostic pacemaker features AF onset scenarios were prospectively evaluated in 612 AF episodes during a 2-month monitoring period, with atrial pacing limited to 40 bpm. The most common onset scenario was premature atrial complexes (PACs) before AF (48% onsets per patient), followed by bradycardia (33%), sudden onset (17%), and tachycardia (0%). Combinations of onset scenarios were frequent (median 2 different scenarios per patient). A main study finding was the significance of repetitive AF, with 33% of onsets per patient being initiated within 5 minutes of a previous AF episode. Sudden onsets were more frequent among patients with than without repetitive AF (24% versus 0% onsets per patient, P =0.011), whereas the proportion of PACs before AF was not statistically different (50% versus 37%, P =0.52); however, patients with repetitive AF had more PACs per hour (72 versus 29, P =0.023) and a higher number of AF episodes per day (17 versus 0, P =0.001) and were more likely to have at least 1 PAC-related onset (90% versus 53%, P <0.0001). Conclusions— Novel diagnostic pacemaker features allowed a detailed individual analysis of rate and rhythm changes before AF and thus uncovered a substantial intraindividual and interindividual variability of AF onset scenarios

Immune checkpoint expression in HNSCC patients before and after definitive chemoradiotherapy

Background Primary platinum-based chemoradiotherapy (CRT) remains the treatment of choice for nonresectable squamous cell carcinoma of the head and neck (HNSCC). Immune-checkpoint modulators are used as palliative therapy and studied in combination with definitive CRT. However, the immunological changes by CRT need yet to be understood. Methods A cohort consisting of 67 paired tissue biopsies (N = 134) of HNSCC patients before and after CRT was created. The expression of PD-1, PD-L1, and CD27 of tumor and immune cells by immunohistochemistry was evaluated. Results PD-L1 expression on immune cells of non-responders was significantly lower before CRT (P = .008). CD27 was expressed only on immune cells and not on cancer cells. A significant lower CD27-expression score was observed following CRT (P = .019). Conclusions Conventional CRT changes the expression of CD27 in the tumor microenvironment. Whether this is due to a loss of expression or a reduction of CD27+ cells must be evaluated in further analyses

A comparison of different Malaise trap types

Recent reports on insect decline have highlighted the need for long-term data on insect communities towards identifying their trends and drivers. With the launch of many new insect monitoring schemes to investigate insect communities over large spatial and temporal scales, Malaise traps have become one of the most important tools due to the broad spectrum of species collected and reduced capture bias through passive sampling of insects day and night. However, Malaise traps can vary in size, shape, and colour, and it is unknown how these differences affect biomass, species richness, and composition of trap catch, making it difficult to compare results between studies. We compared five Malaise trap types (three variations of the Townes and two variations of the Bartak Malaise trap) to determine their effects on biomass and species richness as identified by metabarcoding. Insect biomass varied by 20%–55%, not strictly following trap size but varying with trap type. Total species richness was 20%–38% higher in the three Townes trap models compared to the Bartak traps. Bartak traps captured lower richness of highly mobile taxa but increased richness of ground-dwelling taxa. The white roofed Townes trap captured a higher richness of pollinators. We find that biomass, total richness, and taxa group specific richness are all sensitive to Malaise trap type. Trap type should be carefully considered and aligned to match monitoring and research questions. Additionally, our estimates of trap type effects can be used to adjust results to facilitate comparisons across studies

Encoding NF-κB temporal control in response to TNF: distinct roles for the negative regulators IκBα and A20

TNF-induced NF-κB activity shows complex temporal regulation whose different phases lead to distinct gene expression programs. Combining experimental studies and mathematical modeling, we identify two temporal amplification steps—one determined by the obligate negative feedback regulator IκBα—that define the duration of the first phase of NF-κB activity. The second phase is defined by A20, whose inducible expression provides for a rheostat function by which other inflammatory stimuli can regulate TNF responses. Our results delineate the nonredundant functions implied by the knockout phenotypes of iκbα and a20, and identify the latter as a signaling cross-talk mediator controlling inflammatory and developmental responses

In vitro maturation of Toxoplasma gondii bradyzoites in human myotubes and their metabolomic characterization

The apicomplexan parasite Toxoplasma gondii forms bradyzoite-containing tissue cysts that cause chronic and drug-tolerant infections. However, current in vitro models do not allow long-term culture of these cysts to maturity. Here, we developed a human myotube-based in vitro culture model of functionally mature tissue cysts that are orally infectious to mice and tolerate exposure to a range of antibiotics and temperature stresses. Metabolomic characterization of purified cysts reveals global changes that comprise increased levels of amino acids and decreased abundance of nucleobase- and tricarboxylic acid cycle-associated metabolites. In contrast to fast replicating tachyzoite forms of T. gondii these tissue cysts tolerate exposure to the aconitase inhibitor sodium fluoroacetate. Direct access to persistent stages of T. gondii under defined cell culture conditions will be essential for the dissection of functionally important host-parasite interactions and drug evasion mechanisms. It will also facilitate the identification of new strategies for therapeutic intervention.Peer Reviewe