Search

Eosinophils have been linked to functional dyspepsia; however, less is known about their role in irritable bowel syndrome (IBS). This study tested the hypothesis of alterations in levels of fecal eosinophil-derived neurotoxin (F-EDN) and eosinophil density and degranulation within the colonic mucosa of IBS patients compared with healthy controls (HC). Colonic biopsies were collected from 37 IBS patients and 20 HC and analyzed for eosinophil numbers and local degranulation of eosinophil cationic protein (ECP) by histologic procedures. Fecal samples were collected for F-EDN and microbiota analysis. Differentiated 15HL-60 cells were used in vitro to investigate the direct effect of live bacteria on eosinophil activation measured by a colorimetric assay with o-phenylenediamine (OPD) substrate. We observed a higher number of eosinophils and increased extracellular ECP in the mucosa of IBS patients compared with HC. Moreover, F-EDN levels in IBS samples were elevated compared with HC and positively correlated to extracellular ECP. Metagenomic analysis showed significant correlations between bacterial composition and eosinophil measurements in both HC and IBS patients. In vitro experiments revealed an increased degranulation of 15HL-60 after stimulation with Salmonella typhimurium, Salmonella enterica, and Yersinia enterocolitica. To conclude, we could demonstrate alterations related to eosinophils in IBS, and, for the first time, a positive correlation between F-EDN levels and degranulated eosinophils in the colonic mucosa of IBS patients. Together our results suggest that eosinophils play a role in the pathophysiology of IBS and the mechanisms might be linked to an altered microbiota. Funding Agencies|Apotekare Hedberg Foundation; Magnus Bergvall Foundation [2018-02604]; Bengt Ihre Foundation [SLS-788111, SLS-882561]; Ruth and Richard Julin Foundation [2017-00350, 2019-00347]; County Council of Ostergotland [Lio-934618]; Mucosa Infection and Inflammation Center-MIIC; Medical Faculty, Uppsala University, Uppsala Sweden

TLR‐inducible zinc toxicity is an antimicrobial mechanism utilized by macrophages, however knowledge of molecular mechanisms mediating this response is limited. Here, we show that E. coli exposed to zinc stress within primary human macrophages reside in membrane‐bound vesicular compartments. Since SLC30A zinc exporters can deliver zinc into the lumen of vesicles, we examined LPS‐regulated mRNA expression of Slc30a/SLC30A family members in primary mouse and human macrophages. A number of these transporters were dynamically regulated in both cell populations. In human monocyte‐derived macrophages, LPS strongly up‐regulated SLC30A1 mRNA and protein expression. In contrast, SLC30A1 was not LPS‐inducible in macrophage‐like PMA‐differentiated THP‐1 cells. We therefore ectopically expressed SLC30A1 in these cells, finding that this was sufficient to promote zinc‐containing vesicle formation. The response was similar to that observed following LPS stimulation. Ectopically expressed SLC30A1 localized to both the plasma membrane and intracellular zinc‐containing vesicles within LPS‐stimulated THP‐1 cells. Inducible overexpression of SLC30A1 in THP‐1 cells infected with the Escherichia coli K‐12 strain MG1655 augmented the zinc stress response of intracellular bacteria and promoted clearance. Furthermore, in THP‐1 cells infected with an MG1655 zinc stress reporter strain, all bacteria contained within SLC30A1‐positive compartments were subjected to zinc stress. Thus, SLC30A1 marks zinc‐containing compartments associated with TLR‐inducible zinc toxicity in human macrophages, and its ectopic over‐expression is sufficient to initiate this antimicrobial pathway in these cells. Finally, SLC30A1 silencing did not compromise E. coli clearance by primary human macrophages, suggesting that other zinc exporters may also contribute to the zinc toxicity response., Graphical Abstract The zinc transporter SLC30A1 is LPS‐inducible in human macrophages and can deliver a zinc toxicity response against intracellular Escherichia coli.

The immune response plays a critical role in the pathophysiology of SARS‐CoV‐2 infection ranging from protection to tissue damage and all occur in the development of acute respiratory distress syndrome (ARDS). ARDS patients display elevated levels of inflammatory cytokines and innate immune cells, and T and B cell lymphocytes have been implicated in this dysregulated immune response. Mast cells are abundant resident cells of the respiratory tract and are able to release different inflammatory mediators rapidly following stimulation. Recently, mast cells have been associated with tissue damage during viral infections, but their role in SARS‐CoV‐2 infection remains unclear. In this study, we examined the profile of mast cell activation markers in the serum of COVID‐19 patients. We noticed that SARS‐CoV‐2‐infected patients showed increased carboxypeptidase A3 (CPA3) and decreased serotonin levels in their serum when compared with symptomatic SARS‐CoV‐2‐negative patients. CPA3 levels correlated with C‐reactive protein, the number of circulating neutrophils, and quick SOFA. CPA3 in serum was a good biomarker for identifying severe COVID‐19 patients, whereas serotonin was a good predictor of SARS‐CoV‐2 infection. In summary, our results show that serum CPA3 and serotonin levels are relevant biomarkers during SARS‐CoV‐2 infection. This suggests that mast cells and basophils are relevant players in the inflammatory response in COVID‐19 and may represent targets for therapeutic intervention., Graphical Abstract Serum levels of CPA3 and serotonin are affected during SARS‐CoV‐2 infection and can be considered as biomarkers during COVID‐19.

The global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a highly pathogenic RNA virus causing coronavirus disease 2019 (COVID‐19) in humans. Although most patients with COVID‐19 have mild illness and may be asymptomatic, some will develop severe pneumonia, acute respiratory distress syndrome, multi‐organ failure, and death. RNA viruses such as SARS‐CoV‐2 are capable of hijacking the epigenetic landscape of host immune cells to evade antiviral defense. Yet, there remain considerable gaps in our understanding of immune cell epigenetic changes associated with severe SARS‐CoV‐2 infection pathology. Here, we examined genome‐wide DNA methylation (DNAm) profiles of peripheral blood mononuclear cells from 9 terminally‐ill, critical COVID‐19 patients with confirmed SARS‐CoV‐2 plasma viremia compared with uninfected, hospitalized influenza, untreated primary HIV infection, and mild/moderate COVID‐19 HIV coinfected individuals. Cell‐type deconvolution analyses confirmed lymphopenia in severe COVID‐19 and revealed a high percentage of estimated neutrophils suggesting perturbations to DNAm associated with granulopoiesis. We observed a distinct DNAm signature of severe COVID‐19 characterized by hypermethylation of IFN‐related genes and hypomethylation of inflammatory genes, reinforcing observations in infection models and single‐cell transcriptional studies of severe COVID‐19. Epigenetic clock analyses revealed severe COVID‐19 was associated with an increased DNAm age and elevated mortality risk according to GrimAge, further validating the epigenetic clock as a predictor of disease and mortality risk. Our epigenetic results reveal a discovery DNAm signature of severe COVID‐19 in blood potentially useful for corroborating clinical assessments, informing pathogenic mechanisms, and revealing new therapeutic targets against SARS‐CoV‐2., Graphical Abstract A distinct epigenetic signature associated with severe COVID‐19 exists in blood and is potentially useful for corroborating clinical assessments, informing pathogenic mechanisms, and revealing new therapeutic targets.

Excessive monocyte/macrophage activation with the development of a cytokine storm and subsequent acute lung injury, leading to acute respiratory distress syndrome (ARDS), is a feared consequence of infection with COVID‐19. The ability to recognize and potentially intervene early in those patients at greatest risk of developing this complication could be of great clinical utility. In this study, we performed flow cytometric analysis of peripheral blood samples from 34 COVID‐19 patients in early 2020 in an attempt to identify factors that could help predict the severity of disease and patient outcome. Although we did not detect significant differences in the number of monocytes between patients with COVID‐19 and normal healthy individuals, we did identify significant morphologic and functional differences, which are more pronounced in patients requiring prolonged hospitalization and intensive care unit (ICU) admission. Patients with COVID‐19 have larger than normal monocytes, easily identified on forward scatter (FSC), side scatter analysis by routine flow cytometry, with the presence of a distinct population of monocytes with high FSC (FSC‐high). On more detailed analysis, these CD14+CD16+, FSC‐high monocytes show features of mixed M1/M2 macrophage polarization with higher expression of CD80+ and CD206+ compared with the residual FSC‐low monocytes and secretion of higher levels of IL‐6, IL‐10, and TNF‐α, when compared with the normal controls. In conclusion, the detection and serial monitoring of this subset of inflammatory monocytes using flow cytometry could be of great help in guiding the prognostication and treatment of patients with COVID‐19 and merits further evaluation., Graphical Abstract The presence of larger monocytes with more mature macrophage phenotype in blood drives the dysregulation of immune response in COVID‐19.

Anti‐myelin‐associated glycoprotein (MAG) neuropathy is a disabling autoimmune peripheral neuropathy that is caused by circulating monoclonal IgM autoantibodies directed against the human natural killer‐1 (HNK‐1) epitope. This carbohydrate epitope is highly expressed on adhesion molecules such as MAG, a glycoprotein present in myelinated nerves. We previously showed the therapeutic potential of the glycopolymer poly(phenyl disodium 3‐O‐sulfo‐β‐d‐glucopyranuronate)‐(1→3)‐β‐d‐galactopyranoside (PPSGG) in selectively neutralizing anti‐MAG IgM antibodies in an immunological mouse model and ex vivo with sera from anti‐MAG neuropathy patients. PPSGG is composed of a biodegradable backbone that multivalently presents a mimetic of the HNK‐1 epitope. In this study, we further explored the pharmacodynamic properties of the glycopolymer and its ability to inhibit the binding of anti‐MAG IgM to peripheral nerves. The polymer selectively bound anti‐MAG IgM autoantibodies and prevented the binding of patients’ anti‐MAG IgM antibodies to myelin of non‐human primate sciatic nerves. Upon PPSGG treatment, neither activation nor inhibition of human and murine peripheral blood mononuclear cells nor alteration of systemic inflammatory markers was observed in mice or ex vivo in human peripheral blood mononuclear cells. Intravenous injections of PPSGG to mice immunized against the HNK‐1 epitope removed anti‐MAG IgM antibodies within less than 1 hr, indicating a fast and efficient mechanism of action as compared to a B‐cell depletion with anti‐CD20. In conclusion, these observations corroborate the therapeutic potential of PPSGG for an antigen‐specific treatment of anti‐MAG neuropathy. Read the Editorial Highlight for this article on page 465., Anti‐MAG (myelin‐associated glycoprotein) neuropathy is a disabling autoimmune peripheral neuropathy that is caused by circulating monoclonal IgM autoantibodies directed against the HNK‐1 (human natural killer‐1) epitope. This glycoepitope is highly expressed on adhesion molecules such as MAG and is localized mainly in paranodal loops and Schmidt–Lantermann incisures of the peripheral nervous system. The glycopolymer PPSGG selectively bound anti‐MAG IgM autoantibodies and prevented the binding of patients’ autoantibodies to myelin of primate sciatic nerves in the IFA (indirect fluorescents assay) anti‐MAG IgM assay (right panel). These findings corroborate the therapeutic potential of PPSGG for an antigen‐specific treatment of anti‐MAG neuropathy. Read the Editorial Highlight for this article on page 465.

The CXCR3‐CXCL11 chemokine‐signaling axis plays an essential role in infection and inflammation by orchestrating leukocyte trafficking in human and animal models, including zebrafish. Atypical chemokine receptors (ACKRs) play a fundamental regulatory function in signaling networks by shaping chemokine gradients through their ligand scavenging function, while being unable to signal in the classic G‐protein‐dependent manner. Two copies of the CXCR3 gene in zebrafish, cxcr3.2 and cxcr3.3, are expressed on macrophages and share a highly conserved ligand‐binding site. However, Cxcr3.3 has structural characteristics of ACKRs indicative of a ligand‐scavenging role. In contrast, we previously showed that Cxcr3.2 is an active CXCR3 receptor because it is required for macrophage motility and recruitment to sites of mycobacterial infection. In this study, we generated a cxcr3.3 CRISPR‐mutant to functionally dissect the antagonistic interplay among the cxcr3 paralogs in the immune response. We observed that cxcr3.3 mutants are more susceptible to mycobacterial infection, whereas cxcr3.2 mutants are more resistant. Furthermore, macrophages in the cxcr3.3 mutant are more motile, show higher activation status, and are recruited more efficiently to sites of infection or injury. Our results suggest that Cxcr3.3 is an ACKR that regulates the activity of Cxcr3.2 by scavenging common ligands and that silencing the scavenging function of Cxcr3.3 results in an exacerbated Cxcr3.2 signaling. In human, splice variants of CXCR3 have antagonistic functions and CXCR3 ligands also interact with ACKRs. Therefore, in zebrafish, an analogous regulatory mechanism appears to have evolved after the cxcr3 gene duplication event, through diversification of conventional and atypical receptor variants., CXCR3 paralog with structural characteristics of atypical chemokine receptors regulates the activity of a conventional receptor involved in macrophage motility by scavenging shared ligands.

Pseudomonas aeruginosa-induced corneal keratitis is a sight-threatening disease. The rise of antibiotic resistance among P. aeruginosa keratitis isolates makes treatment of this disease challenging, emphasizing the need for alternative therapeutic modalities. By comparing the responses to P. aeruginosa infection between an outbred mouse strain (Swiss Webster, SW) and a susceptible mouse strain (C57BL6/N), we found that the inherent neutrophil-killing abilities of these strains correlated with their susceptibility to infection. Namely, SW-derived neutrophils were significantly more efficient at killing P. aeruginosa in vitro than C57BL6/N-derived neutrophils. To interrogate whether the distinct neutrophil killing capacities were dependent on endogenous or exogenous factors, neutrophil progenitor cell lines were generated. The in vitro differentiated neutrophils from either SW or C57BL6/N progenitors retained the differential killing abilities, illustrating that endogenous factors conferred resistance. Consistently, quantitative LC-MS/MS analysis revealed strain-specific and infection-induced alterations of neutrophil proteomes. Among the distinctly elevated proteins in the SW-derived proteomes were α-mannosidases, potentially associated with protection. Inhibition of α-mannosidases reduced neutrophil bactericidal functions in vitro. Conversely, topical application of α-mannosidases reduced bacterial biofilms and burden of infected corneas. Cumulatively, these data suggest novel therapeutic approaches to control bacterial biofilm assembly and improve bacterial clearance via enzymatic treatments.

Secondary infections are a major complication of sepsis and associated with a compromised immune state, called sepsis‐induced immunoparalysis. Molecular mechanisms causing immunoparalysis remain unclear; however, changes in cellular metabolism of leukocytes have been linked to immunoparalysis. We investigated the relation of metabolic changes to antimicrobial monocyte functions in endotoxin‐induced immunotolerance, as a model for sepsis‐induced immunoparalysis. In this study, immunotolerance was induced in healthy males by intravenous endotoxin (2 ng/kg, derived from Escherichia coli O:113) administration. Before and after induction of immunotolerance, circulating CD14+ monocytes were isolated and assessed for antimicrobial functions, including cytokine production, oxidative burst, and microbial (Candida albicans) killing capacity, as well metabolic responses to ex vivo stimulation. Next, the effects of altered cellular metabolism on monocyte functions were validated in vitro. Ex vivo lipopolysaccharide stimulation induced an extensive rewiring of metabolism in naive monocytes. In contrast, endotoxin‐induced immunotolerant monocytes showed no metabolic plasticity, as they were unable to adapt their metabolism or mount cytokine and oxidative responses. Validation experiments showed that modulation of metabolic pathways, affected by immunotolerance, influenced monocyte cytokine production, oxidative burst, and microbial (C. albicans) killing in naive monocytes. Collectively, these data demonstrate that immunotolerant monocytes are characterized by a loss of metabolic plasticity and these metabolic defects impact antimicrobial monocyte immune functions. Further, these findings support that the changed cellular metabolism of immunotolerant monocytes might reveal novel therapeutic targets to reverse sepsis‐induced immunoparalysis., Endotoxin‐induced immunotolerant monocytes are characterized by a loss of metabolic plasticity and these metabolic defects impact antimicrobial monocyte immune functions.

Synapses are essential components of neurons and allow information to travel coordinately throughout the nervous system to adjust behavior to environmental stimuli and to control body functions, memories, and emotions. Thus, optimal synaptic communication is required for proper brain physiology, and slight perturbations of synapse function can lead to brain disorders. In fact, increasing evidence has demonstrated the relevance of synapse dysfunction as a major determinant of many neurological diseases. This notion has led to the concept of synaptopathies as brain diseases with synapse defects as shared pathogenic features. In this review, which was initiated at the 13th International Society for Neurochemistry Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental disorders (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer and Parkinson disease). We finally discuss the appropriateness and potential implications of gathering synapse diseases under a single term. Understanding common causes and intrinsic differences in disease‐associated synaptic dysfunction could offer novel clues toward synapse‐based therapeutic intervention for neurological and neuropsychiatric disorders. In this Review, which was initiated at the 13th International Society for Neurochemistry (ISN) Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer's and Parkinson's diseases), gathered together under the term of synaptopathies. Read the Editorial Highlight for this article on page 783.

© 2019 The Authors., Circulating neutrophils are, by necessity, quiescent and relatively unresponsive to acute stimuli. In regions of inflammation, mediators can prime neutrophils to react to acute stimuli with stronger proinflammatory, pathogen‐killing responses. In neutrophils G protein‐coupled receptor (GPCR)‐driven proinflammatory responses, such as reactive oxygen species (ROS) formation and accumulation of the key intracellular messenger phosphatidylinositol (3,4,5)‐trisphosphate (PIP3), are highly dependent on PI3K‐γ, a Ras‐GTP, and Gβγ coincidence detector. In unprimed cells, the major GPCR‐triggered activator of Ras is the Ras guanine nucleotide exchange factor (GEF), Ras guanine nucleotide releasing protein 4 (RasGRP4). Although priming is known to increase GPCR–PIP3 signaling, the mechanisms underlying this augmentation remain unclear. We used genetically modified mice to address the role of the 2 RasGEFs, RasGRP4 and son of sevenless (SOS)1/2, in neutrophil priming. We found that following GM‐CSF/TNFα priming, RasGRP4 had only a minor role in the enhanced responses. In contrast, SOS1/2 acquired a substantial role in ROS formation, PIP3 accumulation, and ERK activation in primed cells. These results suggest that SOS1/2 signaling plays a key role in determining the responsiveness of neutrophils in regions of inflammation., This work was supported by grants from the Biotechnology and Biological Sciences Research Council (BB/J004456/1 and BB/P013384/1).

PSD95 is an abundant postsynaptic scaffold protein in glutamatergic synapses that assembles into supercomplexes composed of over 80 proteins including neurotransmitter receptors, ion channels and adhesion proteins. How these diverse constituents are organized into PSD95 supercomplexes in vivo is poorly understood. Here, we dissected the supercomplexes in mice combining endogenous gene‐tagging, targeted mutations and quantitative biochemical assays. Generating compound heterozygous mice with two different gene‐tags, one on each Psd95 allele, showed that each ~1.5 MDa PSD95‐containing supercomplex contains on average two PSD95 molecules. Gene‐tagging the endogenous GluN1 and PSD95 with identical Flag tags revealed N‐methyl D‐aspartic acid receptors (NMDARs) containing supercomplexes that represent only 3% of the total population of PSD95 supercomplexes, suggesting there are many other subtypes. To determine whether this extended population of different PSD95 supercomplexes use genetically defined mechanisms to specify their assembly, we tested the effect of five targeted mouse mutations on the assembly of known PSD95 interactors, Kir2.3, Arc, IQsec2/BRAG1 and Adam22. Unexpectedly, some mutations were highly selective, whereas others caused widespread disruption, indicating that PSD95 interacting proteins are organized hierarchically into distinct subfamilies of ~1.5 MDa supercomplexes, including a subpopulation of Kir2.3‐NMDAR ion channel‐channel supercomplexes. Kir2.3‐NMDAR ion channel‐channel supercomplexes were found to be anatomically restricted to particular brain regions. These data provide new insight into the mechanisms that govern the constituents of postsynaptic supercomplexes and the diversity of synapse types. Read the Editorial Highlight for this article on page 500. Cover Image for this issue: doi. 10.1111/jnc.13811.

Inherited deficiency in ether lipids, a subgroup of phospholipids whose biosynthesis needs peroxisomes, causes the fatal human disorder rhizomelic chondrodysplasia punctata. The exact roles of ether lipids in the mammalian organism and, therefore, the molecular mechanisms underlying the disease are still largely enigmatic. Here, we used glyceronephosphate O‐acyltransferase knockout (Gnpat KO) mice to study the consequences of complete inactivation of ether lipid biosynthesis and documented substantial deficits in motor performance and muscle strength of these mice. We hypothesized that, probably in addition to previously described cerebellar abnormalities and myelination defects in the peripheral nervous system, an impairment of neuromuscular transmission contributes to the compromised motor abilities. Structurally, a morphologic examination of the neuromuscular junction (NMJ) in diaphragm muscle at different developmental stages revealed aberrant axonal branching and a strongly increased area of nerve innervation in Gnpat KO mice. Post‐synaptically, acetylcholine receptor (AChR) clusters colocalized with nerve terminals within a widened endplate zone. In addition, we detected atypical AChR clustering, as indicated by decreased size and number of clusters following stimulation with agrin, in vitro. The turnover of AChRs was unaffected in ether lipid‐deficient mice. Electrophysiological evaluation of the adult diaphragm indicated that although evoked potentials were unaltered in Gnpat KO mice, ether lipid deficiency leads to fewer spontaneous synaptic vesicle fusion events but, conversely, an increased post‐synaptic response to spontaneous vesicle exocytosis. We conclude from our findings that ether lipids are essential for proper development and function of the NMJ and may, therefore, contribute to motor performance. Read the Editorial Highlight for this article on page 463.

Huntington's disease (HD) is a hereditary neurodegenerative condition with no therapeutic intervention known to alter disease progression, but several trials are ongoing and biomarkers of disease progression are needed. Tau is an axonal protein, often altered in neurodegeneration, and recent studies pointed out its role on HD neuropathology. Our goal was to study whether cerebrospinal fluid (CSF) tau is a biomarker of disease progression in HD. After informed consent, healthy controls, pre‐symptomatic and symptomatic gene expansion carriers were recruited from two HD clinics. All participants underwent assessment with the Unified HD Rating Scale ’99 (UHDRS). CSF was obtained according to a standardized lumbar puncture protocol. CSF tau was quantified using enzyme‐linked immunosorbent assay. Comparisons between two groups were tested using ancova. Pearson's correlation coefficients were calculated for disease progression. Significance level was defined as p

Huntington's disease (HD) is a neurodegenerative condition characterized by pathology in the brain and peripheral tissues. Hyperactivity of the innate immune system, due in part to NFκB pathway dysregulation, is an early and active component of HD. Evidence suggests targeting immune disruption may slow disease progression. Laquinimod is an orally active immunomodulator that down‐regulates proinflammatory cytokine production in peripheral blood mononuclear cells, and in the brain down‐regulates astrocytic and microglial activation by modulating NFκB signalling. Laquinimod had beneficial effects on inflammation, brain atrophy and disease progression in multiple sclerosis (MS) in two phase III clinical trials. This study investigated the effects of laquinimod on hyperactive proinflammatory cytokine release and NFκB signalling in HD patient myeloid cell cultures. Monocytes from manifest (manHD) and pre‐manifest (preHD) HD gene carriers and healthy volunteers (HV) were treated with laquinimod and stimulated with lipopolysaccharide. After 24 h pre‐treatment with 5 μM laquinimod, manHD monocytes released lower levels of IL‐1β, IL‐5, IL‐8, IL‐10, IL‐13 and TNFα in response to stimulation. PreHD monocytes released lower levels of IL‐8, IL‐10 and IL‐13, with no reduction observed in HV monocytes. The effects of laquinimod on dysfunctional NFκB signalling in HD was assessed by inhibitor of kappa B (IκB) degradation kinetics, nuclear translocation of NFκB and interactions between IκB kinase (IKK) and HTT, in HD myeloid cells. No differences were observed between laquinimod‐treated and untreated conditions. These results provide evidence that laquinimod dampens hyper‐reactive cytokine release from manHD and preHD monocytes, with a much reduced effect on HV monocytes. Evidence suggests targeting CNS and peripheral immune disruption may slow Huntington's disease (HD) neurodegenerative processes. The effects of laquinimod, an orally active immunomodulator, on hyperactive cytokine release and dysfunctional NFκB signalling in stimulated myeloid cell cultures from pre‐manifest and manifest HD gene carriers and healthy volunteers were investigated. Laquinimod dampened cytokine release but did not impact NFκB signalling. Read the Editorial Highlight for this article on page 670.

Ethylene glycol monomethyl ether (EGME) is a widely used industrial solvent known to cause adverse effects to human and other mammals. Organs with high metabolism and rapid cell division, such as testes, are especially sensitive to its actions. In order to gain mechanistic understanding of EGME-induced toxicity, an untargeted metabolomic analysis was performed in rats. Male rats were administrated with EGME at 30 and 100 mg/kg/day. At days 1, 4, and 14, serum, urine, liver, and testes were collected for analysis. Testicular injury was observed at day 14 of the 100 mg/kg/day group only. Nearly 1900 metabolites across the four matrices were profiled using liquid chromatography-mass spectrometry/mass spectrometry and gas chromatography-mass spectrometry. Statistical analysis indicated that the most significant metabolic perturbations initiated from the early time points by EGME were the inhibition of choline oxidation, branched-chain amino acid catabolism, and fatty acid β-oxidation pathways, leading to the accumulation of sarcosine, dimethylglycine, and various carnitine- and glycine-conjugated metabolites. Pathway mapping of these altered metabolites revealed that all the disrupted steps were catalyzed by enzymes in the primary flavoprotein dehydrogenase family, suggesting that inhibition of flavoprotein dehydrogenase–catalyzed reactions may represent the mode of action for EGME-induced toxicity. Similar urinary and serum metabolite signatures are known to be the hallmarks of multiple acyl-coenzyme A dehydrogenase deficiency in humans, a genetic disorder because of defects in primary flavoprotein dehydrogenase reactions. We postulate that disruption of key biochemical pathways utilizing flavoprotein dehydrogenases in conjugation with downstream metabolic perturbations collectively result in the EGME-induced tissue damage.

Soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) are crucial for exocytosis, trafficking, and neurite outgrowth, where vesicular SNAREs are directed toward their partner target SNAREs: synaptosomal-associated protein of 25 kDa and syntaxin. SNARE proteins are normally membrane bound, but can be cleaved and released by botulinum neurotoxins. We found that botulinum proteases types C and D can easily be transduced into endocrine cells using DNA-transfection reagents. Following administration of the C and D proteases into normally refractory Neuro2A neuroblastoma cells, the SNARE proteins were cleaved with high efficiency within hours. Remarkably, botulinum protease exposures led to cytotoxicity evidenced by spectrophotometric assays and propidium iodide penetration into the nuclei. Direct delivery of SNARE fragments into the neuroblastoma cells reduced viability similar to botulinum proteases' application. We observed synergistic cytotoxic effects of the botulinum proteases, which may be explained by the release and interaction of soluble SNARE fragments. We show for the first time that previously observed cytotoxicity of botulinum neurotoxins/C in neurons could be achieved in cells of neuroendocrine origin with implications for medical uses of botulinum preparations.

Arsenic is an established lung carcinogen, however, the carcinogenic mechanisms are currently under investigation. Phosphorylation of the epidermal growth factor receptor (EGFR) has been reported with arsenic exposure in bladder cells. EGFR is a tyrosine kinase transmembrane receptor that regulates important processes in carcinogenesis, including cell survival, cell cycle progression, tumor invasion, and angiogenesis. We investigated the mechanisms of EGFR pathway activation by levels of arsenic relevant to human exposure scenarios both in vitro using cultured lung epithelial cells, and in lung tumors samples from New England Lung Cancer Study participants. Toenail arsenic levels were used as an internal biomarker of arsenic exposure. Our in vitro data suggest that arsenic increases levels of the EGFR ligand, heparin binding-EGF, and activate EGFR phosphorylation in the lung. Downstream of EGFR, arsenic exposure increased pERK and cyclin D1 levels. These effects were inhibited by treatment of cultured cells with the EGFR tyrosine kinase inhibitor, Tarceva (erlotinib). In a consecutive series of human lung tumor specimens, pEGFR protein levels were higher in subjects with elevated toenail arsenic levels compared to those with low exposure (odds ratio adjusted for other factors, OR 4.1 (95% confidence interval 1.1–15.6) (p = 0.04). These data suggest that arsenic exposure may stimulate EGFR pathway activation in the lung. Moreover, the tumors that arise in arsenic-exposed individuals also exhibit signs of EGFR pathway dysregulation. Further work is needed to assess the clinical utility of targeting the EGFR pathway in subgroups of lung cancer patients who have been exposed to elevated levels of arsenic.

Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy, increased ventricular stiffness and impaired diastolic filling. We investigated to what extent myocardial functional defects can be explained by alterations in the passive and active properties of human cardiac myofibrils. Skinned ventricular myocytes were prepared from patients with obstructive HCM (two patients with MYBPC3 mutations, one with a MYH7 mutation, and three with no mutation in either gene) and from four donors. Passive stiffness, viscous properties, and titin isoform expression were similar in HCM myocytes and donor myocytes. Maximal Ca2+-activated force was much lower in HCM myocytes (14 ± 1 kN/m2) than in donor myocytes (23 ± 3 kN/m2; P, Research Highlights ► The passive stiffness of skinned HCM cardiac myocytes was similar to that of normal (donor) myocytes. ► Maximum Ca-activated force production was reduced by 40% in HCM vs donor myocytes. ► This loss of force could contribute to systolic dysfunction in HCM hearts. ► Myofibrillar Ca sensitivity was higher in HCM than in donor myocytes. ► The enhanced Ca sensitivity could compensate for the smaller maximum force but would tend to cause diastolic dysfunction. ► These characteristics were common to all HCM patients studied, suggesting the changes were secondary consequence of the underlying genetic variants.