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Gut microbiota regulate intestinal function and health. However, mounting evidence indicates that they can also influence the immune and nervous systems and vice versa. This article reviews the bidirectional relationship between the gut microbiota and the brain, termed the microbiota-gut-brain (MGB) axis, and discusses how it contributes to the pathogenesis of certain disorders that may involve brain inflammation. Articles were identified with a search of Medline (starting in 1980) by using the key words anxiety, attention-deficit hypersensitivity disorder (ADHD), autism, cytokines, depression, gut, hypothalamic–pituitary–adrenal (HPA) axis, inflammation, immune system, microbiota, nervous system, neurologic, neurotransmitters, neuroimmune conditions, psychiatric, and stress. Various afferent or efferent pathways are involved in the MGB axis. Antibiotics, environmental and infectious agents, intestinal neurotransmitters/neuromodulators, sensory vagal fibers, cytokines, and essential metabolites all convey information to the central nervous system about the intestinal state. Conversely, the hypothalamic–pituitary–adrenal axis, the central nervous system regulatory areas of satiety, and neuropeptides released from sensory nerve fibers affect the gut microbiota composition directly or through nutrient availability. Such interactions seem to influence the pathogenesis of a number of disorders in which inflammation is implicated, such as mood disorder, autism-spectrum disorders, attention-deficit hypersensitivity disorder, multiple sclerosis, and obesity. Recognition of the relationship between the MGB axis and the neuroimmune systems provides a novel approach for better understanding and management of these disorders. Appropriate preventive measures early in life or corrective measures such as use of psychobiotics, fecal microbiota transplantation, and flavonoids are discussed.

Mast cell (MC) activation disorders present with multiple symptoms including flushing, pruritus, hypotension, gastrointestinal complaints, irritability, headaches, concentration/memory loss and neuropsychiatric issues. These disorders are classified as: cutaneous and systemic mastocytosis with a c-kit mutation and clonal MC activation disorder, allergies, urticarias and inflammatory disorders and mast cell activation syndrome (MCAS), idiopathic urticaria and angioedema. MCs are activated by IgE, but also by cytokines, environmental, food, infectious, drug and stress triggers, leading to secretion of multiple mediators. The symptom profile and comorbidities associated with these disorders, such as chronic fatigue syndrome and fibromyalgia, are confusing. We propose the use of the term 'spectrum' and highlight the main symptoms, useful diagnostic tests and treatment approaches.

Bruton’s tyrosine kinase (BTK) is crucial for FcεRI-mediated mast cell activation and essential for autoantibody production by B cells in chronic spontaneous urticaria (CSU). Fenebrutinib, an orally administered, potent, highly selective, reversible BTK inhibitor, may be effective in CSU. This double-blind, placebo-controlled, phase 2 trial (EudraCT ID 2016-004624-35 ) randomized 93 adults with antihistamine-refractory CSU to 50 mg daily, 150 mg daily and 200 mg twice daily of fenebrutinib or placebo for 8 weeks. The primary end point was change from baseline in urticaria activity score over 7 d (UAS7) at week 8. Secondary end points were the change from baseline in UAS7 at week 4 and the proportion of patients well-controlled (UAS7 ≤ 6) at week 8. Fenebrutinib efficacy in patients with type IIb autoimmunity and effects on IgG-anti-FcεRI were exploratory end points. Safety was also evaluated. The primary end point was met, with dose-dependent improvements in UAS7 at week 8 occurring at 200 mg twice daily and 150 mg daily, but not at 50 mg daily of fenebrutinib versus placebo. Asymptomatic, reversible grade 2 and 3 liver transaminase elevations occurred in the fenebrutinib 150 mg daily and 200 mg twice daily groups (2 patients each). Fenebrutinib diminished disease activity in patients with antihistamine-refractory CSU, including more patients with refractory type IIb autoimmunity. These results support the potential use of BTK inhibition in antihistamine-refractory CSU. Fenebrutinib, an oral Bruton’s tyrosine kinase inhibitor, reduces disease activity in patients with chronic spontaneous urticaria refractory to antihistamines, suggesting that this treatment type could be an alternative to standard of care anti-IgE therapy.

The diverse repertoire of T-cell receptors (TCR) plays a key role in the adaptive immune response to infections. Using TCR alpha and beta repertoire sequencing for T-cell subsets, as well as single-cell RNAseq and TCRseq, we track the concentrations and phenotypes of individual T-cell clones in response to primary and secondary yellow fever immunization — the model for acute infection in humans — showing their large diversity. We confirm the secondary response is an order of magnitude weaker, albeit ∼10 days faster than the primary one. Estimating the fraction of the T-cell response directed against the single immunodominant epitope, we identify the sequence features of TCRs that define the high precursor frequency of the two major TCR motifs specific for this particular epitope. We also show the consistency of clonal expansion dynamics between bulk alpha and beta repertoires, using a new methodology to reconstruct alpha-beta pairings from clonal trajectories.

Coronary microvascular obstruction (MVO) occurs in up to 57% of patients suffering from ST-segment elevation myocardial infarction (STEMI). One cause for MVO is distal embolization by microthrombi after percutaneous coronary intervention (PCI) of the infarct-related coronary artery. MVO is associated with an adverse cardiac prognosis post-STEMI. However, there are no evidence-based therapies for MVO, presenting an unmet therapeutic need. We investigated a novel pharmacotherapeutic approach to resolve embolizing MVO using an in vitro microfluidic model with porcine or human microthrombi to investigate thrombolysis with alteplase, a fibrinolytic drug. We show that a brief (90 s) exposure to concentrated microdoses of alteplase significantly reduces microthrombus size by up to 75%. 50% lysis occurred within six to twelve minutes after alteplase exposure depending on the initial microdose. Our results suggest that delivering a therapeutic drug directly to the microvasculature to briefly achieve high local drug concentrations has the potential to address embolizing MVO. The combination of short drug exposure and high local concentration is possible with a recently developed infusion system based on intracoronary controlled flow infusion (CoFI). CoFI uses microdoses of alteplase that are up to 1300 times lower than intravenous doses and could thereby minimize bleeding risk.

Despite the prevalence and high heritability of Attention-Deficit/Hyperactivity Disorder (ADHD), genetic etiology remains elusive. Clinical evidence points in part to reduced function of the striatum, but which specific genes are differentially expressed and how they sculpt striatal physiology to predispose ADHD are not well understood. As an exploratory tool, a polygenic mouse model of ADHD was recently developed through selective breeding for high home cage activity. Relative to the Control line, the High-Active line displays hyperactivity and motor impulsivity which are ameliorated with amphetamine. This study compared gene expression in the striatum between Control and High-Active mice to develop a coherent hypothesis for how genes might affect striatal physiology and predispose ADHD-like symptoms. To this end, striatal transcriptomes of High-Active and Control mice were analyzed after mice were treated with saline or amphetamines. The pseudogene Gm6180 for n-cofilin (Cfl1) displayed 20-fold higher expression in High-Active mice corresponding with reduced Cfl1 expression suggesting synaptic actin dysregulation. Latrophilin 3 (Lphn3), which is associated with ADHD in human populations and is involved in synapse structure, and its ligand fibronectin leucine rich transmembrane protein 3 (Flrt3), were downregulated in High-Active mice. Multiple genes were altered in High-Active mice in a manner predicted to downregulate the canonical Wnt pathway. A smaller and different set of genes including glyoxalase (Glo1) were differentially regulated in High-Active as compared to Control in response to amphetamine. Together, results suggest genes involved in excitatory synapse regulation and maintenance are downregulated in ADHD-like mice. Consistent with the molecular prediction, stereological analysis of the striatum from a separate set of mice processed for imunohistochemical detection of synaptophysin revealed approximately a 46% reduction in synaptophysin immunoreactivity in High-Active relative to Control. Results provide a new set of molecular targets related to synapse maintenance for the next generation of ADHD medicines.

Objectives: The aim of this study was to evaluate the effectiveness of sequential treatments with adrenocorticotropic hormone (ACTH) or ketogenic diet therapy (KDT) in infants with infantile epileptic spasms syndrome (IESS) who did not achieve seizure freedom after initial treatment with either KDT or ACTH. Methods: We conducted a cohort study following a parallel-cohort randomized controlled trial comparing KDT with ACTH as first-line treatment for IESS. Infants who failed to respond were switched per protocol to the alternative treatment (ACTH or KDT) or, if this was not feasible or unsuccessful, to anti-seizure medications (ASMs). The primary outcome was the frequency of sustained seizure freedom at last follow-up. Results: Of 101 infants allocated to the initial treatment phase, N = 67 required further treatment. Of these, 31% (21/67) achieved sustained seizure freedom after the second treatment phase, and 15% (7/46) after rescue treatment with ASMs. KDT as the second treatment achieved sustained seizure freedom in 50% (12/24), compared to 19% (3/16) with ACTH and 9% (2/22) with ASMs. The cumulative response rate after the first and second treatments was 64% for the KDT-ACTH sequence and 68% for the ACTH-KDT sequence. The cumulative response after all three treatment phases was 78% (KDT-ACTH-ASM) and 72% (ACTH-KDT-ASM), respectively. Conclusions: KDT is at least as effective as ACTH as a second treatment and significantly more effective than ASMs in achieving sustained seizure freedom in infants with IESS.