Marginal Cells Research Articles

Cutaneous lymphomas : Clinical presentation- diagnosis- treatment

Cutaneous lymphomas comprise different subgroups with distinct biological behavior. Mycosis fungoides, the most common cutaneous lymphoma, presents with patches, plaques, tumors and erythroderma. Therapeutic options depend on stage and comprise local skin-directed treatment in early stages, while later stages and Sézary syndrome require systemic therapies including bexarotene, interferon or brentuximab vedotin. While the rare CD4-positive lymphoproliferation and acral CD8-positive lymphoma present with an invariably indolent course, cutaneous peripheral T‑cell lymphomas exhibit an aggressive clinical behavior. Among the subgroup of cutaneous B‑cell lymphomas, primary cutaneous marginal zone lymphoma and follicle center cell lymphoma belong to indolent entities with almost unrestricted overall survival, whereas cutaneous large B‑cell lymphoma presents with asignificant risk of systemic dissemination and is associated with high lethality.

Cellular and Biochemical Changes in Different Categories of Periodontitis: A Patient-based Study.

ABSTRACTObjectives:The aim of this study was to study the effects of periodontitis, diabetes mellitus (DM), and tobacco smoking and chewing habits (TBSCH) on the oxidative stress biomarker levels, namely malondialdehyde (MDA), and the mucosal genotoxic nuclear damage in the marginal gingival cells of subjects. Furthermore, the correlation of the biomarkers, MDA, and nuclear changes in the form of micronucleation (Mn) and binucleation (Bn) was investigated.Materials and Methods:Forty study participants were divided into five subject categories, which were established based on the presence of periodontitis, DM, and TBSCH. Whole saliva and marginal gingival smears collected from subjects were used to determine MDA levels and nuclear changes, respectively. A full-mouth assessment of periodontal pocket depth, clinical attachment loss, and bleeding on probing was performed for each subject to determine periodontal status.Results:MDA and Mn levels between control group and subjects with only periodontitis (MDA: P < 0.9990; Mn: P < 0.8200) showed no significant difference, whereas levels among subjects with DM, TBSCH, and periodontitis, and all other categories were statistically significant (MDA: P < 0.001). DM and/or TBSCH superimposed on periodontitis cause an exponential increase in biomarker levels. Furthermore, MDA and Mn showed poor correlation (r = 0.162; P = 0.318). Periodontitis alone did not significantly increase oxidative stress levels compared to healthy controls, whereas DM and TBSCH resulted in augmented oxidative stress levels, implying that increased stress produced by DM and TBSCH aggravates or exaggerates periodontal inflammation.Conclusion:Poor correlation between MDA and Mn indicated that the mechanisms involved in their production are independent of each other.

Porella perrottetiana var. angustifolia (Porellaceae, Marchantiophyta), new to China, and taxonomic revision of Porella perrottetiana in the East Yunnan-Guizhou Plateau

Cao, W., Xiong, Y.-X., Zhao, D.-G., Qu, J.-J. & Tan, H.-Y. 2019. Porella perrottetiana var. angustifolia (Porellaceae, Marchantiophyta), new to China, and taxonomic revision of Porella perrottetiana in the East Yunnan-Guizhou Plateau. – Herzogia 32: 344 –356.Porella perrottetiana var. angustifolia (Porellaceae, Marchantiophyta), a neglected variety known from North Vietnam, is reported here as a new addition to the Chinese liverwort flora from east of the Yunnan-Guizhou Plateau, SW China. It is characterized and distinguished from known Chinese species of Porella by attenuately ligulate or lanceolate and falcate leaf lobes with a long terminal and 0 – 4(–5) lateral ciliate teeth, median cells significantly larger than marginal cells, and by forming vitta from base to apex of leaf lobes. Detailed illustrations and description of this variety, an identification key to three varieties of Porella perrottetiana as well as a taxonomic revision of Porella perrottetiana in east of the Yunnan-Guizhou Plateau are provided.

Distribution of tight junctions in the primate cochlear lateral wall

The blood-labyrinth barrier (BLB) is a major structure that separates the inner ear from the systemic blood circulation. Many drugs cannot access the inner ear because of their inability to cross the BLB. In the cochlea, the BLB is mainly distributed in the lateral wall. However, the ultrastructure of the cochlear lateral wall, including the distribution of tight junctions (TJs), which are its main component, has not been thoroughly examined in primates. This study investigated the distribution of TJs in the cochlear lateral wall of the common marmoset by performing immunohistochemistry for TJ markers and transmission electron microscopy. As previously reported in rodents, TJs were distributed at the lumenal side of stria marginal cells and basal cells. In outer sulcus cells, which are more developed in primates than in rodents, TJs were distributed at the side with the endolymph but not at the side with the spiral ligament, where many capillaries were located. These findings indicate that drugs and small compounds circulating systemically in the blood can easily access outer sulcus cells, but have a limited ability to enter endolymph. No structural differences were detected between species, indicating that the in vivo distribution of drugs in cochlear lateral wall cells, including outer sulcus cells, in primates can be predicted by performing rodent experiments.

Transcription factor Tlx1 marks a subset of lymphoid tissue organizer-like mesenchymal progenitor cells in the neonatal spleen

The spleen is comprised of spatially distinct compartments whose functions, such as immune responses and removal of aged red blood cells, are tightly controlled by the non-hematopoietic stromal cells that provide regionally-restricted signals to properly activate hematopoietic cells residing in each area. However, information regarding the ontogeny and relationships of the different stromal cell types remains limited. Here we have used in vivo lineage tracing analysis and in vitro mesenchymal stromal cell assays and found that Tlx1, a transcription factor essential for embryonic spleen organogenesis, marks neonatal stromal cells that are selectively localized in the spleen and retain mesenchymal progenitor potential to differentiate into mature follicular dendritic cells, fibroblastic reticular cells and marginal reticular cells. Furthermore, by establishing a novel three-dimensional cell culture system that enables maintenance of Tlx1-expressing cells in vitro, we discovered that signals from the lymphotoxin β receptor and TNF receptor promote differentiation of these cells to express MAdCAM-1, CCL19 and CXCL13, representative functional molecules expressed by different subsets of mature stromal cells in the spleen. Taken together, these findings indicate that mesenchymal progenitor cells expressing Tlx1 are a subset of lymphoid tissue organizer-like cells selectively found in the neonatal spleen.

Dll1 and Dll4 Notch Ligands Prime T Cell Alloimmunity and Are Expressed in Non-Overlapping Populations of Fibroblastic Stromal Cells in Spleen and Lymph Nodes at the Onset of Gvhd

Notch signaling drives graft-versus-host-disease (GVHD) pathogenesis in preclinical models of allogeneic hematopoietic cell transplantation (allo-HCT). Short-term systemic blockade of the Notch ligands Delta-like1 (Dll1) and Delta-like4 (Dll4) within two days of allo-HCT conferred long-term protection from acute GVHD lethality in mice, with a dominant impact of Dll4. Surprisingly, critical Notch ligands in GVHD were provided by radioresistant non-hematopoietic fibroblastic stromal cells lineage traced by a Ccl19-Cre transgene in secondary lymphoid organs (SLO) (Chung, JCI 2017). Our discovery revises prevailing GVHD models and identifies a pathogenic role for a stromal cell niche expressing Notch ligands in SLOs. However, little is known about the distribution and regulation of Dll1/Dll4-expressing cells among SLO stromal cells. To address this question, we deployed genetic and biochemical tools to map expression of Notch ligands in SLO stromal cells, characterize the transcriptional landscape of these cells, and identify putative regulators of Notch ligand expression. To map Dll1 and Dll4 expression, we combined a Ccl19-Cre transgene with a ROSA26-YFP Cre-activated allele and Dll1-mCherry or Dll4-mCherry BAC reporters. Using this model, we fluorescently traced all cells derived from Ccl19-Cre+ cells which contain the essential Dll1/Dll4 source in GVHD, while detecting Dll1 vs. Dll4 expression with high sensitivity. Within the lymph node (LN) Ccl19-Cre+ROSA26-YFP+ compartment, Dll4-mCherry was present predominantly among CD157hi CD45-Ter119-CD31-gp38+ fibroblastic stromal cells, including fibroblastic reticular cells (FRCs), marginal reticular cells (MRCs) and follicular dendritic cells (FDCs). In the spleen, Dll4-mCherry was detected among both CD157+ cells (predominant in the T-zone) and CD157- cells. In contrast, Dll1-mCherry was abundant among spleen CD157+ and CD157- cells, but not detected in the corresponding LN compartments. Thus, Dll1 and Dll4 are expressed with a non-overlapping distribution pattern in different SLOs and stromal cell subsets. Next, we studied expression of the dominant Dll4 ligand after MHC-mismatched allo-HCT (BALB/c into C57BL/6). Although Dll4-mCherry fluorescence did not increase, we detected a rise in surface Dll4 protein, peaking 12 hrs after allo-HCT in LN Ccl19-Cre+ CD157hi FRCs, MRCs and FDCs. Increased Dll4 abundance coincided with the critical timing of pathogenic Notch signals within days after allo-HCT and required irradiation conditioning as well as infusion of allogeneic T cells, suggesting a crosstalk between alloreactive T cells and Dll4+ stromal cells. The mechanisms underlying increased surface Dll4 abundance are under investigation, but could involve post-transcriptional effects as the Dll4-mCherry transcriptional reporter did not change. We next characterized transcriptomic features of Dll4+ fibroblastic stromal cells. We performed RNA-Seq on rare SLO stromal cells sort-purified from LNs at baseline and 12 hrs after allo-HCT. We compared CD157hi FRCs that do or do not express Dll4-mCherry, while including CD157lo FRCs that do not express Dll4-mCherry and lymphatic endothelial cells that express Dll4 at high levels as controls. These populations were sort-purified for RNA-Seq analysis, using the data to produce a comprehensive picture of gene expression and regulatory machinery in the SLO niche in alloimmunity, as well as identify new putative regulators of Notch ligand expression. Interestingly, we found only 13 differentially expressed genes between Ccl19-Cre-expressing CD157hi fibroblastic stromal cells that do and do not express the Dll4-mCherry reporter 12 hrs after transplant (log-fold change ≥ 1, corrected p ≤ 0.01). The list of up-regulated transcripts included Cxcl13, encoding a chemokine produced by FDCs, and Rankl, encoding a TNF-family member important in LN development and homeostasis. In summary, our data uncover key new features of the specialized fibroblastic stromal cells expressing Delta-like Notch ligands in SLOs. Ongoing work is testing how qualitative and quantitative differences in Dll1 and Dll4's effects during GVHD may relate to their distribution, regulated expression, or biochemical properties as they interact with Notch receptors in T cells. Our ultimate goal is to design strategies that target Notch ligand expression in SLOs as new prophylactic approaches in GVHD. Disclosures Blazar: Magenta Therapeutics and BlueRock Therapeuetics: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics, Inc.: Research Funding; Tmunity: Other: Co-Founder; KidsFirst Fund: Research Funding; Childrens' Cancer Research Fund: Research Funding; Leukemia and Lymphoma Society: Research Funding; Abbvie Inc: Research Funding; Alpine Immune Sciences, Inc.: Research Funding; RXi Pharmaceuticals: Research Funding; Regeneron Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Five Prime Therapeutics Inc: Co-Founder, Membership on an entity's Board of Directors or advisory committees; Kamon Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees; BlueRock Therapeutics: Membership on an entity's Board of Directors or advisory committees. Maillard:Genentech: Consultancy; Regeneron: Consultancy.

TBX1 is required for normal stria vascularis and semicircular canal development

Little is known about the role of TBX1 in post-otocyst stages of inner ear development. Here, we report on mice with a missense mutation of Tbx1 that are viable with fully developed but abnormally formed inner ears. Mutant mice are deaf due to an undeveloped stria vascularis and show vestibular dysfunction associated with abnormal semicircular canal formation. We show that TBX1 is expressed in endolymph-producing strial marginal cells and vestibular dark cells of the inner ear and is an upstream regulator of Esrrb, which previously was shown to control the developmental fate of these cells. We also show that TBX1 is expressed in sensory cells of the crista ampullaris, which may relate to the semicircular canal abnormalities observed in mutant mice. Inner ears of mutant embryos have a non-resorbed fusion plate in the posterior semicircular canal and a single ampulla connecting anterior and lateral canals. We hypothesize that the TBX1 missense mutation prevents binding with specific co-regulatory proteins. These findings reveal previously unknown functions of TBX1 during later stages of inner ear development.

Thallus ontogeny, morphology and molecular phylogeny of Madagascaria atlantica sp. nov. (Compsopogonophyceae, Rhodophyta), a diminutive crustose species uncovered in the Atlantic Ocean

Madagascaria is a crustose monotypic genus belonging to the class Compsopogonophyceae, so far known only from the Indo-Pacific region. The taxonomy within this group is difficult since it includes genera with small dimensions (<5 mm) and few diagnostic characters. In this study, we combined thallus development in culture with morphological and molecular data to uncover a new species of Madagascaria and the first record in the Atlantic Ocean (Piauí coast, northeastern Brazil). The new species was isolated from rhodoliths cultured under laboratory conditions, and its thallus ontogeny was analyzed. Morphological observations, along with molecular data based on rbcL sequences, allowed us to identify the small crustose red algae as closely related to M. erythrocladioides from the type locality (Madagascar). Madagascaria atlantica sp. nov. from Brazil is characterized by crusts with initially filamentous growth, free marginal cells and asexual reproduction by monospores. Our analyses support three evolutionary lineages in Madagascaria, corresponding to isolates from Brazil (M. atlantica), Japan and Madagascar. The rbcL sequence divergence between M. atlantica and samples from Madagascar and Japan was 2.4% and 6.9%, respectively. Madagascaria atlantica and M. erythrocladioides are indistinguishable with overlapping features. Our findings evidence the existence of cryptic species diversity and suggest that Madagascaria is probably a widely distributed genus. Molecular evidence based on rbcL gene supports the recognition of M. atlantica as a new cryptic species. Since the small size and resemblance to other crustose rhodophycean, data from other regions are needed to evaluate the distributional range of Madagascaria.

The marginal cells of the Caenorhabditis elegans pharynx scavenge cholesterol and other hydrophobic small molecules

The nematode Caenorhabditis elegans is a bacterivore filter feeder. Through the contraction of the worm’s pharynx, a bacterial suspension is sucked into the pharynx’s lumen. Excess liquid is then shunted out of the buccal cavity through ancillary channels made by surrounding marginal cells. We find that many worm-bioactive small molecules (a.k.a. wactives) accumulate inside of the marginal cells as crystals or globular spheres. Through screens for mutants that resist the lethality associated with one crystallizing wactive we identify a presumptive sphingomyelin-synthesis pathway that is necessary for crystal and sphere accumulation. We find that expression of sphingomyelin synthase 5 (SMS-5) in the marginal cells is not only sufficient for wactive accumulation but is also important for absorbing exogenous cholesterol, without which C. elegans cannot develop. We conclude that sphingomyelin-rich marginal cells act as a sink to scavenge important nutrients from filtered liquid that might otherwise be shunted back into the environment.

Downregulation of p66Shc can reduce oxidative stress and apoptosis in oxidative stress model of marginal cells of stria vascularis in Sprague Dawley rats.

Backgroundp66Shc, a Src homologue and collagen homologue (Shc) adaptor protein, mediates oxidative stress signaling. The p66Shc-null mice have increased lifespan and enhanced resistance to oxidative stress. Studies have also indicated its potential role in inner ear aging, which can lead to deafness.ObjectiveThe aim of this study was to determine the effects of p66Shc down-regulation on the marginal cells (MCs) of the inner ear stria vascularis.MethodsPrimary MCs were isolated from neonatal rats and treated with glucose oxidase to induce oxidative stress. The cells were transduced with adenovirus expressing siRNA, and the knockdown was verified by Western blotting. The reactive oxygen species (ROS) levels and apoptosis were analyzed using the DCFH-DA probe and Annexin-V/7-AAD staining respectively. The ultrastructure of the differentially-treated cells was examined by transmission electron microscopy (TEM).Results: The in vitro oxidative stress model was established successfully in rat MCs. Knockdown of p66Shc alleviated the high ROS levels and apoptosis in the glucose oxidase-treated cells. In addition, glucose oxidase significantly increased the number of peroxisomes in the MCs, which was decreased by p66Shc inhibition.ConclusionOxidative stress increases p66Shc levels in the marginal cells of the inner ear, which aggravates ROS production and cellular injury. Blocking p66Shc expression can effectively reduce oxidative stress and protect the MCs.

Mechanisms of zebrafish epiboly: A current view.

Epiboly is a conserved gastrulation movement describing the thinning and spreading of a sheet or multi-layer of cells. The zebrafish embryo has emerged as a vital model system to address the cellular and molecular mechanisms that drive epiboly. In the zebrafish embryo, the blastoderm, consisting of a simple squamous epithelium (the enveloping layer) and an underlying mass of deep cells, as well as a yolk nuclear syncytium (the yolk syncytial layer) undergo epiboly to internalize the yolk cell during gastrulation. The major events during zebrafish epiboly are: expansion of the enveloping layer and the internal yolk syncytial layer, reduction and removal of the yolk membrane ahead of the advancing blastoderm margin and deep cell rearrangements between the enveloping layer and yolk syncytial layer to thin the blastoderm. Here, work addressing the cellular and molecular mechanisms as well as the sources of the mechanical forces that underlie these events is reviewed. The contribution of recent findings to the current model of epiboly as well as open questions and future prospects are also discussed.

Effect of SOD2 methylation on mitochondrial DNA4834-bp deletion mutation in marginal cells under oxidative stress.

Presbycusis, or age-related hearing loss, is a prevalent disease that severely affects the physical and mental health of the elderly. Oxidative stress and mitochondrial (mt)DNA deletion mutation are considered as major factors in the pathophysiology of age-related hearing loss. The 4977-bp deletion in human mtDNA (common deletion, corresponding to the 4834-bp mtDNA deletion in rats) is suggested to be closely associated with the pathogenesis of age-related hearing loss. Superoxide dismutase 2 (SOD2), an isoform of SOD that is exclusively expressed in the intracellular mitochondrial matrix, plays a crucial role in oxidative resistance against mitochondrial superoxide. Previous research has shown that methylation of the promoter region of the SOD2 gene decreased the expression of SOD2 in marginal cells (MCs) extracted from the inner ear of rats subjected to D-galactose-induced mtDNA4834 deletion. However, the relationship between SOD2 methylation and mtDNA4834 deletion under oxidative stress remains to be elucidated. Herein, an oxidative damage model was established in the extracted MCs using hydrogen peroxide (H2O2), which increased the methylation level of SOD2 and the copy number of mtDNA4834 mutation in MCs. Decreasing the methylation level of SOD2 using 5-azacytidine, a DNA methylation inhibitor, reduced oxidative stress and the copy number of mtDNA4834 mutation and inhibited H2O2-induced apoptosis. The present work demonstrates that decreasing the methylation of SOD2 suppresses the mtDNA4834 deletion in MCs under oxidative stress and provides potential insights to the intervention therapy of aging-related hearing loss.

Human B1 Cells are the Main Blood Group A-Specific B Cells That Have a Moderate Correlation With Anti-A Antibody Titer.

BackgroundAnti-carbohydrate antibody responses, including those of anti-blood group ABO antibodies, are yet to be thoroughly studied in humans. Because anti-ABO antibody-mediated rejection is a key hurdle in ABO-incompatible transplantation, it is important to understand the cellular mechanism of anti-ABO responses. We aimed to identify the main human B cell subsets that produce anti-ABO antibodies by analyzing the correlation between B cell subsets and anti-ABO antibody titers.MethodsBlood group A-binding B cells were analyzed in peritoneal fluid and peripheral blood samples from 43 patients undergoing peritoneal dialysis and 18 healthy volunteers with blood group B or O. The correlation between each blood group A-specific B cell subset and anti-A antibody titer was then analyzed using Pearson's correlation analysis.ResultsBlood group A-binding B cells were enriched in CD27+CD43+CD1c− B1, CD5+ B1, CD11b+ B1, and CD27+CD43+CD1c+ marginal zone-B1 cells in peripheral blood. Blood group A-specific B1 cells (P=0.029 and R=0.356 for IgM; P=0.049 and R=0.325 for IgG) and marginal zone-B1 cells (P=0.011 and R=0.410 for IgM) were positively correlated with anti-A antibody titer. Further analysis of peritoneal B cells confirmed B1 cell enrichment in the peritoneal cavity but showed no difference in blood group A-specific B1 cell enrichment between the peritoneal cavity and peripheral blood.ConclusionsHuman B1 cells are the key blood group A-specific B cells that have a moderate correlation with anti-A antibody titer and therefore constitute a potential therapeutic target for successful ABO-incompatible transplantation.

B cells from young and old mice switch isotypes with equal frequencies after ex vivo stimulation

To determine whether old B cells have the same capacity to switch isotypes as young cells, we purified splenic follicular, marginal zone, and age-associated B cell subsets from C57BL/6 mice. Cells were stimulated in culture with interleukin 4 and either lipopolysaccharide or anti-CD40, and switching to IgG1 was measured by flow cytometry of surface immunoglobulin. The results show that switching was robust in follicular and marginal zone B cells from old mice and was comparable to their young counterparts. However, age-associated B cells from old mice switched poorly relative to the other subsets. Expression of activation-induced deaminase, which initiates switching, was quantified by qPCR of mRNA, and it was equal between young and old follicular B cells. Thus, in this ex vivo system, the follicular and marginal zone cells from young and old mice behaved similarly, showing that the molecular machinery to perform switching is intact in old B cells.

Allicin Protects against Cisplatin-Induced Stria Vascularis Damage: Possible Relation to Inhibition of Caspase-3 and PARP-1-AIF-Mediated Apoptotic Pathways

Cisplatin is an anti-cancer drug that causes oxotoxic side effects such as impairment of inner ear function and hearing loss. We aimed to investigate the effects of allicin against cisplatin-induced stria vascularis damage in mice, and to clarify the mechanism underlying the protective effects of allicin against ototoxicity. Stria vascularis injury was induced in mice by intraperitoneal injection of cisplatin, which was significantly prevented by pretreatment with allicin. Allicin not only reduced cisplatin-activated expression of cleaved caspase-3 in marginal cells, PVM/Ms (perivascular resident macrophage-like melanocytes), and basal cells of the stria vascularis, but also decreased the expression of poly(ADP-ribose) polymerase-1 (PARP-1) and apoptosis-inducing factor (AIF) nuclear translocation in the stria vascularis cells. Our results demonstrate that allicin plays an effective role in protecting stria vascularis injury induced by cisplatin by inhibiting caspase-dependent, as well as caspase-independent PARP-1-AIF-mediated apoptotic pathways. Therefore, allicin may be useful in preventing cisplatin-induced ototoxicity.

In Vivo Confocal Microscopy of Cornea in Patients with Terrien's Marginal Corneal Degeneration.

This study was aimed at observing the morphological changes of the cornea with ocular in vivo confocal microscopy (IVCM) in patients with Terrien's marginal degeneration (TMD). Ten patients (20 eyes) with TMD treated in the Department of Ophthalmology, Xiangya Hospital, and 10 healthy controls (20 eyes) were included in the current study. A detailed slit lamp microscopy, anterior segment photography, and corneal IVCM examination were performed for each eye. The density of central and marginal corneal epithelial cells, stromal cells, and subepithelial nerve fibers was compared between the two groups using the Wilcoxon rank sum test. Compared with the control group, the corneal epithelial and endothelial cells in the TMD group showed granular highly reflective substances and thinner subepithelial nerve fibers. The uneven dot-like highly reflective substances without cell structures appeared in the stromal layer of the cornea. The density of central and marginal corneal epithelial cells, stromal cells, and subepithelial nerve fibers was lower in the TMD group (p < 0.05), and they were negatively correlated with severity of the disease (p < 0.05). Our study demonstrated that the density of corneal epithelial cells, stromal cells, and sensory plexus nerve fibers was significantly reduced in the TMD group. The pathological changes were more obvious in the marginal cornea, and it is correlated with severity of the disease.

Updated taxonomy of Lactifluus section Luteoli: L. russulisporus from Australia and L. caliendrifer from Thailand

Lactifluusrussulisporus Dierickx & De Crop and Lactifluuscaliendrifer Froyen & De Crop are described from eucalypt forests in Queensland, Australia and different forest types in Thailand, respectively. Both species have recently been published on Index Fungorum and fit morphologically and molecularly in L.sect.Luteoli, a section within L.subg.Gymnocarpi that encompasses species with alboochraceous basidiomes, white latex that stains brown and typical capitate elements in the pileipellis and/or marginal cells.

Inflammation up-regulates cochlear expression of TRPV1 to potentiate drug-induced hearing loss.

Aminoglycoside antibiotics are essential for treating life-threatening bacterial infections, despite the risk of lifelong hearing loss. Infections induce inflammation and up-regulate expression of candidate aminoglycoside-permeant cation channels, including transient receptor potential vanilloid-1 (TRPV1). Heterologous expression of TRPV1 facilitated cellular uptake of (fluorescently tagged) gentamicin that was enhanced by agonists, and diminished by antagonists, of TRPV1. Cochlear TRPV1 was immunolocalized near the apical membranes of sensory hair cells, adjacent supporting cells, and marginal cells in the stria vascularis. Exposure to immunostimulatory lipopolysaccharides, to simulate of bacterial infections, increased cochlear expression of TRPV1 and hair cell uptake of gentamicin. Lipopolysaccharide exposure exacerbated aminoglycoside-induced auditory threshold shifts and loss of cochlear hair cells in wild-type, but not in heterozygous Trpv1+/- or Trpv1 knockout, mice. Thus, TRPV1 facilitates cochlear uptake of aminoglycosides, and bacteriogenic stimulation upregulates TRPV1 expression to exacerbate cochleotoxicity. Furthermore, loss-of-function polymorphisms in Trpv1 can protect against immunogenic exacerbation of aminoglycoside-induced cochleotoxicity.

Abstract 4813: Comparative activity profiling of tyrosine kinase inhibitors (TKIs) against exon 20 insertions and the wild-type form of epidermal growth factor receptor (EGFR)

Abstract Exon 20 insertions (Ex20Ins) have been identified in approximately 5% of epidermal growth factor receptor (EGFR)-mutated lung tumours in patients presenting with non-small cell lung cancer (NSCLC). Several small molecule tyrosine kinase inhibitors (TKIs) have been reported to have pre-clinical activity against such insertions including afatinib, poziotinib, osimertinib, nazartinib, AP32788/TAK-788 and TAS6417. However, there remains a lack of approved treatments for patients with Ex20Ins with early approved EGFR agents appearing to be ineffective in this setting. Poziotinib, osimertinib and AP32788/TAK-788 are undergoing clinical evaluation in patients whose tumours carry Ex20Ins and in some cases clinical responses have been reported giving hope that such insertions can be targeted by small molecules. There is however a need for comparable data across such compounds that would enable understanding of the relative activity of these compounds between Ex20Ins and the wild-type form of EGFR. As many of the Exon 20 insertions are not part of the ATP binding pocket achieving selectivity over wild type EGFR is highly challenging and may limit the clinical utility of agents due to dose limiting EGFR wild-type driven toxicity. A selection of TKIs were profiled for Ex20Ins and wild-type EGFR activity using biochemical, in vitro cellular phosphorylation and proliferation assays. This has enabled us to differentiate the Ex20Ins versus wild-type EGFR selectivity profiles of a range of pre-clinical, clinical and proprietary compounds. As part of this evaluation we utilized a CRISPR CAS9 approach in H2073 EGFR wild-type NSCLC cell line, where we have established cellular disease models against the most prevalent insertions including D770-N771insSVD (22%). Finally, we will show anti-tumour efficacy data for a selection of these inhibitors along with a potential combination approach of osimertinib and cetuximab. EGFR D770-N771InsSVD cell phospho IC50 (µM)EGFR WT (H2073) cell phospho IC50 (µM)Fold-EGFR WT margin (cell)afatinib0.0060.00330.5osimertinib0.0940.414.4poziotinib0.00340.00351TAS64170.0230.0672.9AZ62810.0972.223 Citation Format: Richard A. Ward, Ambra Bianco, Nicola Colclough, Darren Cross, Emanuela M. Cuomo, M. Raymond V. Finlay, Martina Fitzek, Nicolas Floc’h, Sladjana Gagrica, Beverley Hammond, Matthew J. Martin, Darren McKerrecher, Daniel J. O’Neill, Jonathan P. Orme, Paul D. Smith, Anna D. Staniszewska, Jelena Urosevic, Nicky Whalley, James W. Yates. Comparative activity profiling of tyrosine kinase inhibitors (TKIs) against exon 20 insertions and the wild-type form of epidermal growth factor receptor (EGFR) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4813.

Didymodon ochyrarum (Pottiaceae, Bryophyta), a new Andean species from tropical South America

Abstract A new moss species, Didymodon ochyrarum J.A. Jiménez &amp; M.J. Cano, is described and illustrated from the tropical Andean highlands of Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina. The species is distinguished morphologically by its lanceolate to long-lanceolate leaves that are strongly appressed when dry, leaf base widely ovate, acute apices, plane leaf margins and distally bistratose, excurrent costa, epapillose laminal cells, and marginal basal cells running up the margin forming a distinctly differentiated area of transversely thick-walled cells. Drawings and light microscope photographs of the new species are provided, and possible confusion with other closely related taxa is discussed.