Hesperetin inhibits KSHV reactivation and is reversed by HIF1α overexpression

Kaposi’s sarcoma-associated herpesvirus (KSHV), an oncogenic virus, has two life cycle modes: the latent and lytic phases. KSHV lytic reactivation is important for both viral propagation and KSHV-induced tumorigenesis. The KSHV replication and transcription activator (RTA) protein is essential for lytic reactivation. Hesperetin, a citrus polyphenolic flavonoid, has antioxidant, anti-inflammatory, hypolipidemic, cardiovascular and anti-tumour effects. However, the effects of hesperetin on KSHV replication and KSHV-induced tumorigenesis have not yet been reported. Here, we report that hesperetin induces apoptotic cell death in BCBL-1 cells in a dose-dependent manner. Hesperetin inhibits KSHV reactivation and reduces the production of progeny virus from KSHV-harbouring cells. We also confirmed that HIF1α promotes the RTA transcriptional activities and lytic cycle-refractory state of KSHV-infected cells. Hesperetin suppresses HIF1α expression to inhibit KSHV lytic reactivation. These results suggest that hesperetin may represent a novel strategy for the treatment of KSHV infection and KSHV-associated lymphomas.

Periodic modes of group dominance in fully coupled neural networks

Nonlinear systems of differential equations with delay, which are mathematical models of fully connected networks of impulse neurons, are considered. Purpose of this work is to study the dynamic properties of one special class of solutions to these systems. Large parameter methods are used to study the existence and stability in сonsidered models of special periodic motions – the so-called group dominance or k-dominance modes, where k ∈ N. Results. It is shown that each such regime is a relaxation cycle, exactly k components of which perform synchronous impulse oscillations, and all other components are asymptotically small. The maximum number of stable coexisting group dominance cycles in the system with an appropriate choice of parameters is 2m − 1, where m is the number of network elements. Conclusion. Considered model with maximum possible number of couplings allows us to describe the most complex and diverse behavior that may be observed in biological neural associations. A feature of the k-dominance modes we have considered is that some of the network neurons are in a non-working (refractory) state. Each periodic k-dominance mode can be associated with a binary vector (α1, α2, . . . , αm), where αj = 1 if the j-th neuron is active and αj = 0 otherwise. Taking this into account, we come to the conclusion that these modes can be used to build devices with associative memory based on artificial neural networks.

Relaxed tarantula skeletal muscle has two ATP energy-saving mechanisms

Myosin molecules in the relaxed thick filaments of striated muscle have a helical arrangement in which the heads of each molecule interact with each other, forming the interacting-heads motif (IHM). In relaxed mammalian skeletal muscle, this helical ordering occurs only at temperatures >20°C and is disrupted when temperature is decreased. Recent x-ray diffraction studies of live tarantula skeletal muscle have suggested that the two myosin heads of the IHM (blocked heads [BHs] and free heads [FHs]) have very different roles and dynamics during contraction. Here, we explore temperature-induced changes in the BHs and FHs in relaxed tarantula skeletal muscle. We find a change with decreasing temperature that is similar to that in mammals, while increasing temperature induces a different behavior in the heads. At 22.5°C, the BHs and FHs containing ADP.Pi are fully helically organized, but they become progressively disordered as temperature is lowered or raised. Our interpretation suggests that at low temperature, while the BHs remain ordered the FHs become disordered due to transition of the heads to a straight conformation containing Mg.ATP. Above 27.5°C, the nucleotide remains as ADP.Pi, but while BHs remain ordered, half of the FHs become progressively disordered, released semipermanently at a midway distance to the thin filaments while the remaining FHs are docked as swaying heads. We propose a thermosensing mechanism for tarantula skeletal muscle to explain these changes. Our results suggest that tarantula skeletal muscle thick filaments, in addition to having a superrelaxation–based ATP energy-saving mechanism in the range of 8.5–40°C, also exhibit energy saving at lower temperatures (<22.5°C), similar to the proposed refractory state in mammals.

Belantamab Mafodotin to Treat Multiple Myeloma: A Comprehensive Review of Disease, Drug Efficacy and Side Effects

Multiple myeloma (MM) is a hematologic malignancy characterized by excessive clonal proliferation of plasma cells. The treatment of multiple myeloma presents a variety of unique challenges due to the complex molecular pathophysiology and incurable status of the disease at this time. Given that MM is the second most common blood cancer with a characteristic and unavoidable relapse/refractory state during the course of the disease, the development of new therapeutic modalities is crucial. Belantamab mafodotin (belamaf, GSK2857916) is a first-in-class therapeutic, indicated for patients who have previously attempted four other treatments, including an anti-CD38 monoclonal antibody, a proteosome inhibitor, and an immunomodulatory agent. In November 2017, the FDA designated belamaf as a breakthrough therapy for heavily pretreated patients with relapsed/refractory multiple myeloma. In August 2020, the FDA granted accelerated approval as a monotherapy for relapsed or treatment-refractory multiple myeloma. The drug was also approved in the EU for this indication in late August 2020. Of note, belamaf is associated with the following adverse events: decreased platelets, corneal disease, decreased or blurred vision, anemia, infusion-related reactions, pyrexia, and fetal risk, among others. Further studies are necessary to evaluate efficacy in comparison to other standard treatment modalities and as future drugs in this class are developed.

A Sum Score to Define Therapy-Refractory Myasthenia Gravis: A German Consensus

Background and purpose: In 2017, eculizumab has been approved for treatment-refractory generalised myasthenia gravis (TRgMG). The German Myasthenia Foundation has published a consensus statement on the use of eculizumab, with a recent update. However, a treatment-refractory state is still ill-defined and the term warrants further clarification. We aimed at developing a sum score to operationalise the definition of a TRgMG status, which is easy- to-handle in clinical decision making. Methods: We established a structured consensus process according to the Delphi consensus methodology, with 12 members of the medical advisory board of the German Myasthenia Foundation. Accordingly, 4 consensus rounds were accomplished. Additionally, a literature survey covering the years 2004-2020 was done and relevant information offered to the consensus group. Consensus criteria were predefined. In the consensus process the relative importance of scoring items were to be consented, with a sum score of 20 and above indicating a TRgMG status. Results: The sum score considers the categories disease severity, inefficiency of antecedent therapies, cessation of therapies due to side effects, and long term stay on the intensive care unit. Categories were specified by a total of 13 scoring items. Eventually, the Delphi process developed an unanimous scoring consensus. Conclusion: We suggest a sum score to define treatment refractory state in generalised myasthenia gravis. Beyond clarifying the indication of eculizumab, this easy-to-handle score facilitates clinical decision making and offers new inclusion criteria for clinical studies that explore new therapeutic perspectives in myasthenia gravis treatment.

The Mysteries of Capsaicin-Sensitive Afferents

A fundamental subdivision of nociceptive sensory neurons is named after their unique sensitivity to capsaicin, the pungent ingredient in hot chili peppers: these are the capsaicin-sensitive afferents. The initial excitation by capsaicin of these neurons manifested as burning pain sensation is followed by a lasting refractory state, traditionally referred to as “capsaicin desensitization,” during which the previously excited neurons are unresponsive not only to capsaicin but a variety of unrelated stimuli including noxious heat. The long sought-after capsaicin receptor, now known as TRPV1 (transient receptor potential cation channel, subfamily V member 1), was cloned more than two decades ago. The substantial reduction of the inflammatory phenotype of Trpv1 knockout mice has spurred extensive efforts in the pharmaceutical industry to develop small molecule TRPV1 antagonists. However, adverse effects, most importantly hyperthermia and burn injuries, have so far prevented any compounds from progressing beyond Phase 2. There is increasing evidence that these limitations can be at least partially overcome by approaches outside of the mainstream pharmaceutical development, providing novel therapeutic options through TRPV1. Although ablation of the whole TRPV1-expressing nerve population by high dose capsaicin, or more selectively by intersectional genetics, has allowed researchers to investigate the functions of capsaicin-sensitive afferents in health and disease, several “mysteries” remain unsolved to date, including the molecular underpinnings of “capsaicin desensitization,” and the exact role these nerves play in thermoregulation and heat sensation. This review tries to shed some light on these capsaicin mechanisms.

A Thermodynamic Model of Mesoscale Neural Field Dynamics: Derivation and Linear Analysis

ABSTRACTMotivated by previous research suggesting that mesoscopic collective activity has the defining characteristics of a turbulent system, we postulate a thermodynamic model based on the fundamental assumption that the activity of a neuron is characterized by two distinct stages: a sub-threshold stage, described by the value of mean membrane potential, and a transitional stage, corresponding to the firing event. We therefore distinguish between two types of energy: the potential energy released during a spike, and the internal kinetic energy that triggers a spike. Formalizing these assumptions produces a system of integro-differential equations that generalizes existing models [Wilson and Cowan, 1973, Amari, 1977], with the advantage of providing explicit equations for the evolution of state variables. The linear analysis of the system shows that it supports single- or triple-point equilibria, with the refractoriness property playing a crucial role in the generation of oscillatory behavior. In single-type (excitatory) systems this derives from the natural refractory state of a neuron, producing “refractory oscillations” with periods on the order of the neuron refractory period. In dual-type systems, the inhibitory component can provide this functionality even if neuron refractory period is ignored, supporting mesoscopic-scale oscillations at much lower activity levels. Assuming that the model has any relevance for the interpretation of LFP measurements, it provides insight into mesocale dynamics. As an external forcing, theta may play a major role in modulating key parameters of the system: internal energy and excitability (refractoriness) levels, and thus in maintaining equilibrium states, and providing the increased activity necessary to sustain mesoscopic collective action. Linear analysis suggest that gamma oscillations are associated with the theta trough because it corresponds to higher levels of forced activity that decreases the stability of the equilibrium state, facilitating mesoscopic oscillations.

First responders shape a prompt and sharp NF-κB–mediated transcriptional response to TNF-α

SummaryNF-κB acts as the master regulator of the transcriptional response to inflammatory signals by translocating into the nucleus upon stimuli, but we lack a single-cell characterization of the resulting transcription dynamics. Here we show that transcription of NF-κB target genes is strongly heterogeneous in individual cells but dynamically coordinated at the population level, since the average nascent transcription is prompt (i.e. occurs almost immediately) and sharp (i.e. increases and decreases rapidly) compared to NF-κB nuclear localization. Using an NF-κB-controlled MS2 reporter we confirm that the population-level transcriptional activity emerges from a strongly heterogeneous response in single cells as compared to NF-κB translocation dynamics, including the presence of a fraction of “first responders”. Mathematical models show that a combination of NF-κB mediated gene activation and a gene activity module including a gene refractory state is enough to produce sharp and prompt transcriptional responses. Our data and models show how the expression of the target genes of a paradigmatic inducible transcription activator upon stimuli can be time-resolved at population level and yet heterogeneous across single cells.

Understanding the glioblastoma immune microenvironment as basis for the development of new immunotherapeutic strategies

Cancer immunotherapy by immune checkpoint blockade has proven its great potential by saving the lives of a proportion of late stage patients with immunogenic tumor types. However, even in these sensitive tumor types, the majority of patients do not sufficiently respond to the therapy. Furthermore, other tumor types, including glioblastoma, remain largely refractory. The glioblastoma immune microenvironment is recognized as highly immunosuppressive, posing a major hurdle for inducing immune-mediated destruction of cancer cells. Scattered information is available about the presence and activity of immunosuppressive or immunostimulatory cell types in glioblastoma tumors, including tumor-associated macrophages, tumor-infiltrating dendritic cells and regulatory T cells. These cell types are heterogeneous at the level of ontogeny, spatial distribution and functionality within the tumor immune compartment, providing insight in the complex cellular and molecular interplay that determines the immune refractory state in glioblastoma. This knowledge may also yield next generation molecular targets for therapeutic intervention.