Epistemic_Statements  

CORD-19:552539784ecd39d1e2344cfc4fd2e13b81140d54 JSONTXT 11 Projects

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Id Subject Object Predicate Lexical cue
T1 1418-1618 Epistemic_statement denotes Antigen presentation by cells expressing major histocompatibility complex class II (MHC class II) molecules on their surface is an important step in the initiation of the primary immune response [1] .
T2 1717-1881 Epistemic_statement denotes These cells play a major role in the processing of inhaled antigens and may participate in the pathogenesis of infectious and allergic airway diseases [2] [3] [4] .
T3 1946-2045 Epistemic_statement denotes However, the DC network rapidly expands after exposure to a variety of pathogens and antigens [6] .
T4 2046-2214 Epistemic_statement denotes For example, exposure to aerosolized heat-inactivated Moraxella catarrhalis causes DC influx into the airways which peaks within 3 h and remains elevated for 48 h [5] .
T5 2507-2623 Epistemic_statement denotes Such stimuli can also evoke transient expression of MHC class II molecules by airway epithelial cells [8] [9] [10] .
T6 3657-3878 Epistemic_statement denotes Although some of these changes may occur after viral infection [20, 21] , M. pulmonis infection is unusual in that it causes life-long disease and, if untreated, can result in severe remodeling of the airway mucosa [22] .
T7 3879-4116 Epistemic_statement denotes The role of DC and other MHC class II expressing cells in these changes is unknown [16, 17] , but is of interest because of the rapid cellular response after infection and the strong immunological component of mycoplasmal airway disease.
T8 4433-4536 Epistemic_statement denotes We also determined whether epithelial cells express MHC class II molecules after M. pulmonis infection.
T9 7446-7572 Epistemic_statement denotes Alternatively, 150-lm cross-sections were cut with a Vibratome (Series 1000, Technical Products International, St. Louis, MO).
T10 10175-10389 Epistemic_statement denotes These particular cells were selected so the measurements would reflect the cells near the M. pulmonis organisms in the airway lumen, and the values would be comparable to published data on subepithelial DC [2, 3] .
T11 13371-13656 Epistemic_statement denotes Increasing OX6 immunoreactivity of mucosal cells made cell-counting more difficult in tracheal whole mounts after the first week; however, an analysis of cross-sections showed that OX6-positive cells were uniformly abundant throughout the mucosa at 1 and 4 weeks after infection (Figs.
T12 14271-14407 Epistemic_statement denotes By 1 week, most of the epithelium had granular OX6 immunoreactivity, which appeared to be associated with intracellular organelles (Fig.
T13 15627-15748 Epistemic_statement denotes In these preparations, we could see the 3-dimensional shape as well as determine the distribution of cells in the mucosa.
T14 15921-16061 Epistemic_statement denotes Only the most superficial OX6-positive cells were counted in whole mounts so the values could be related to data from previous studies [3] .
T15 16258-16362 Epistemic_statement denotes This difference could be explained by the greater thickness of the region analyzed in the present study.
T16 16363-16574 Epistemic_statement denotes The combination of whole mounts and cross-sections produced a picture of OX6-positive cells that neither method could give independently and could not be readily obtained from conventional histological sections.
T17 16760-16959 Epistemic_statement denotes However, as the mucosa became thicker, only the most superficial cells of whole mounts were stained, probably due to limited penetration of reagents and increasing immunoreactivity of the epithelium.
T18 16960-17155 Epistemic_statement denotes By comparison, cross-sections, which did not have the limitation of reagent penetration, clearly revealed the thickening of the mucosa and showed abundant OX6positive cells throughout the mucosa.
T19 17695-17893 Epistemic_statement denotes In addition, OX6-positive cells, which are most abundant at the base of the epithelium, can be distinguished from ED2-positive tissue macrophages, which are most numerous deeper in the mucosa [18] .
T20 17894-18078 Epistemic_statement denotes Although tissue macrophages in pathogen-free rats may have cytoplasmic processes, they typically do not express MHC class II determinants in the absence of antigenic stimulation [29] .
T21 18270-18511 Epistemic_statement denotes The characteristic branched morphology of DC in pathogen-free rats was no longer present in the OX6-positive cell population 1 week after infection and could, therefore, not be used to distinguish DC from other MHC class II expressing cells.
T22 18512-18677 Epistemic_statement denotes Accordingly, some OX6-positive cells observed after infection may represent activated macrophages or B lymphocytes that have infiltrated the airway mucosa [15, 31] .
T23 18824-18906 Epistemic_statement denotes For example, activated B-cells could be identified by using OX12 as a marker [8] .
T24 18907-19186 Epistemic_statement denotes However, it is unlikely that activated macrophages make a major contribution to the OX6-positive cell population, because in infected ani-mals they acquire a distinctive distribution around angiogenic blood vessels, quite different from the pattern of OX6 immunoreactivity [18] .
T25 19619-19805 Epistemic_statement denotes Rounded DC precursors are not seen in control animals, and their transformation from rounded to stellate phenotype is most likely explained by local factors affecting DC maturation [5] .
T26 19948-20074 Epistemic_statement denotes Perhaps the transformation from stellate to rounded phenotype reflects changes in DC maturation, differentiation, or motility.
T27 20075-20236 Epistemic_statement denotes Alternatively, the apparent change in DC phenotype may represent the gradual replacement of stellate DC by rounded MHC class II expressing cells such as B-cells.
T28 20871-20965 Epistemic_statement denotes Exposure to aerosolized bacteria can increase the number of OX6positive DC within 1 h [5, 6] .
T29 20966-21201 Epistemic_statement denotes By contrast, the kinetics and time course of OX6-positive cell recruitment seen with M. pulmonis infection is closer to the response demonstrated by Sendai virus infection, which peaks at 3-5 days and remains elevated for 2 weeks [8] .
T30 21405-21608 Epistemic_statement denotes The strong OX6 immunoreactivity of columnar epithelial cells that developed after M. pulmonis infection is consistent with the establishment of persistent infection and the corresponding immune response.
T31 22165-22340 Epistemic_statement denotes It is not clear whether the M. pulmonis organisms themselves or perhaps their ability to stimulate IFN-c production is driving the MHC class II expression by epithelial cells.
T32 22856-23046 Epistemic_statement denotes The rounding of OX6-positive cells after infection suggests that existing DC change shape during maturation or differentiation or are replaced by OX6-positive cells with a rounded phenotype.
T33 23047-23263 Epistemic_statement denotes Changes in the OX6-positive cell population probably reflect the activation of an adaptive immune response and may play a role in the progression to chronic disease by persistently stimulating T lymphocyte responses.