Isabelle Joris

Memory CD8+ T cells in heterologous antiviral immunity and immunopathology in the lung

A potent role for memory CD8+ T cells in heterologous immunity was shown with a respiratory mucosal model of viral infection. Memory CD8+ T cells generated after lymphocytic choriomeningitis virus (LCMV) infection were functionally activated in vivo to produce interferon-γ (IFN-γ) during acute infection with vaccinia virus (VV). Some of these antigen-specific memory cells selectively expanded in number, which resulted in modulation of the original LCMV-specific T cell repertoire. In addition, there was an organ-selective compartmental redistribution of these LCMV-specific T cells during VV infection. The presence of these LCMV-specific memory T cells correlated with enhanced VV clearance, decreased mortality and marked changes in lung immunopathology. Thus, the participation of pre-existing memory T cells specific to unrelated agents can alter the dynamics of mucosal immunity and disease course in response to a pathogen.

Specific History of Heterologous Virus Infections Determines Anti-Viral Immunity and Immunopathology in the Lung

Having previously shown that previous immunity to one virus can influence the host response to a subsequent unrelated virus, we questioned whether the outcome to a given virus infection would be altered in similar or different ways by previous immunity to different viruses, and whether immunity to a given virus would have similar effects on all subsequent infections. In mouse models of respiratory viral infections, immunity to lymphocytic choriomeningitis virus (LCMV), murine cytomegalovirus (MCMV), or influenza A virus enhanced both Th1-type cytokine responses and viral clearance in the lung on vaccinia virus infection. A common pathological feature was the presence of chronic mononuclear infiltrates instead of the acute polymorphonuclear response seen in the infected nonimmune mice, but some pathologies such as enhanced bronchus-associated lymphoid tissue and bronchiolitis obliterans were unique for the immunizing virus, LCMV. Immunity to influenza virus influenced subsequent infections diversely, inhibiting vaccinia virus but enhancing LCMV and MCMV titers and completely altering cytokine profiles. Influenza virus immunity enhanced the mild mononuclear responses usually observed during acute infections with MCMV or LCMV in nonimmune mice, but unique features such as enhanced bronchiolization and mononuclear consolidation occurred during MCMV infection of influenza virus-immune mice. Heterologous immunity induced two patterns of disease outcome dependent on the specific virus infection sequence: improved, if the acute response switched from a neutrophilic to a lymphocytic response or worsened, if it switched from a mild to a severe lymphocytic response. Heterologous immunity thus occurs between many viruses, resulting in altered protective immunity and lung immunopathology, and this is influenced by the specific virus infection sequence.

Vascular labelling with monastral blue B

Vascular labelling is an established technique of experimental pathology whereby leaky vessels can be identified in vivo. A suspension of a suitable colloidal pigment is injected intravenously; the pigment is then trapped in the wall of the leaky vessels. The colloidal preparation of carbon black, which has been used for many years for this purpose, is no longer commercially available. This communication introduces a substitute: Monastral blue B which gives beautiful preparations in whole mounts, is readily visible in paraffin and plastic embedded histologic sections, has a distinctive appearance in electron micrographs, and is nontoxic in the required dosage.

Cellular breakdown within the arterial wall: An ultrastructural study of the coronary artery in young and aging rats

The coronary arteries were studied by electron microscopy in normal rats weighing 65 to 535 gm; fixation was accomplished by perfusion for 20 min at 110–130 mm Hg. In rats of all ages (but especially in the oldest) the arterial wall contained deposits of abnormal intercellular material, consisting of granules, vesicles, myelin figures and other debris. These deposits were present in the intima and media, but rare in the adventitia; there was suggestive evidence that medial cells phagocytized some of the material. The adventitia was characterized by 1–4 layers of cells with extremely thin protoplasmic expansions wrapped around the vessel (“veil cells”) and containing lysosome-like bodies as well as phagosomes. These findings, taken as a whole, suggest the following sequence of events. During normal life, the media produces cellular debris, by cell death as well as by fragmentation of cellular processes; part of these debris are phagocytized by smooth muscle cells, part diffuse outward to the adventitia where they are taken up by specialized cells (the “veil cells”). However, due to relative inadequacy of phagocytosis in the media, the debris continue to accumulate and form intercellular deposits that increase with age. It is possible that this natural phenomenon may by itself set a maximal limit to the life-span of the arterial wall.

Endothelium 1977: A Review

This paper is conceived as a short update of the review published in 1965 (1). It is based on a set of 2,476 references assembled through a MEDLARS search limited to the single word endothelium (January 1966 – June 1977; a few references were added up to the end of 1977). Much to our regret, we were obliged to omit from our search the word capillary which would have yielded an unmanageable number of additional papers. About 5% of the MEDLARS titles referred to corneal endothelium and were eliminated. This decision, which was based on limitations of space, may well have discarded relevant data: vascular and corneal endothelium are both mesodermal structures, and although the corneal endothelium has some attributes which appear to be distinctive, such as a water pump (2), other properties are similar (3). In limiting the number of references to about 500, arbitrary choices had to be made; papers obviously belonging under the headings of inflammation, atherosclerosis, or thrombosis were not included and will be found in other portions of this volume. Some of the inevitable gaps will be filled by the bibliography of the papers quoted herein, by other reviews (4–15), and by the proceedings of the A. Benzon Symposium of 1969 (16).

Quantitation of oil red O staining of the aorta in hypercholesterolemic rats

A technique is described which provides morphologic and quantitative data on the amount of oil red O (ORO) staining in thoracic aortas of rats fed a high cholesterol diet. Samples are stained with ORO, the dye is extracted, and the concentration of ORO in the extract is measured colorimetrically. Wistar rats fed ad libitum either standard chow (control group: n = 15) or chow supplemented with 4% cholesterol, 1% cholic acid, and 0.5% thiouracil (CCT group: n = 23) were maintained on these diets for 1, 3, 6, 9, or 12 months. Plasma cholesterol levels averaged overall 87 and 737 mg/dl for the control and CCT groups, respectively. Animals were killed under anesthesia by perfusion fixation with formalin or glutaraldehyde, and samples of thoracic aorta were stained with ORO. After microscopic study en face and measurement of surface area, the ORO was extracted in chloroform-methanol (2:1). Concentrations of ORO (microM) were determined from a standard curve and expressed as microM/mm2 of aorta. Aortas of CCT animals showed progressive diet- and time-dependent increases in the amount of ORO staining compared to controls. We conclude that this method yields reliable quantitative data applicable to studying atherosclerosis in small animals.

Endothelium and “silver lines”

The significance of endothelial “silver lines” was studied by TEM in rat aortas after perfusion with glutaraldehyde followed by silver nitrate. Standard TEM technique proved unsatisfactory (coarse silver granules, imprecise localization, artefacts). Exposure of the silver-treated aortas to photographic fixer markedly improved the image of the deposits leaving fine, stable, uniform “residual granules” about 100 Å in diameter. Most of these granules were localized along the intercellular junctions; they also tended to pool in the basement membrane beneath each junction. This image suggests that the Ag+ ions pass through the junction, and react with its contents as well as with the basement membrane beyond it. A scheme is proposed to explain the reaction of Ag+ ions with anions and negatively charged radicals within the junction. It is concluded that the “silver lines” represent not only a histochemical effect, but also the visualization of a transendothelial electrolyte pathway.

Adriamycin impairs phagocytic function and induces morphologic alterations in human neutrophils

Normal human polymorphonuclear leukocytes (PMNL) were preincubated in vitro with methotrexate, 5‐fluorouracil, vincristine, cisplatin, Adriamycin (doxorubicin), and daunomycin for 15 hours before being tested in a phagocytic–bactericidal assay. Anthracycline‐treated PMNL were defective in phagocytosis and killing of the bacteria, in contrast to the other chemotherapeutic agents which allowed the PMNL to remain functional. The defect of Adriamycin‐treated PMNL resulted from decreased ingestion: 3 μg/ml Adriamycin inhibited by 50% of the uptake of Oil Red‐O particles. In this assay, the proportion of noningesting PMNL increased from ≦20% with 0.62 μg/ml to ≧90% with 10 μg/ml Adriamycin. Electron microscopy revealed that Adriamycin‐inactivated PMNL had rounded up, were depleted in glycogen, and had undergone profound nuclear changes. RNA and protein synthesis in PMNL were also affected. Adriamycin, besides producing neutropenia, may decrease the phagocytic function of circulating PMNL.

Developmental regulation of thyrotropin receptor gene expression in the fetal and neonatal rat thyroid: relation to thyroid morphology and to thyroid-specific gene expression.

The TSH receptor plays a pivotal role in thyroid gland function, growth, and differentiation, but little is known about its role or regulation in the fetus and neonate. To explore these questions, we systematically evaluated TSH receptor gene expression at the level of messenger RNA (mRNA) in thyroid glands obtained from rat fetuses and neonates, from 14 days gestation to day 5 of postnatal life. Results were compared with histological evidence of differentiation and to thyroid-specific gene expression. Northern blot and RT-PCR analysis revealed that TSH mRNA was first detected at low levels on fetal day 15, but it increased 3- to 15-fold on fetal days 17–18. Up-regulation of TSH receptor mRNA on fetal day 17–18 was accompanied by the first appearance of colloid formation and of follicular development on morphological examination. It was also paralleled by increased expression of the thyroid-specific genes thyroglobulin (Tg) and thyroid peroxidase. Unexpectedly, TSH mRNA abundance was 2- to 3-fold higher ...

Cellular changes during hypertension: A quantitative study of the rat aorta☆

Using rats made hypertensive by aortic ligation or by the one kidney--one clip method, we searched the aorta for morphologic clues that could explain why hypertension aggravates atherosclerosis. Both atherosclerosis and hypertension are characterized by an increased migration of mononuclear cells into the aortic intima; we therefore quantitated this phenomenon and studied its time course. In the thoracic aorta of hypertensive rats intimal cells (emigrated mononuclear cells) increased up to 15 times 2 weeks after surgery and remained stationary thereafter. In both control and experimental rats, leukocyte emigration was heavier in the thoracic aorta than in the abdominal region. A two- to threefold increase in medial smooth muscle herniae into the intima (myointimal herniae) was also found at 8 weeks, indicating a smooth muscle cell dysfunction. Electron microscopic study of the intima showed that its thickening was due to blood-borne material and also to extracellular matrix synthesized by the endothelium. Heightened secretion reflects cell activation, a condition that (in the endothelium) leads also to leukocyte adhesion. These data suggest that, in renovascular hypertension, the aortic endothelium is in an activated state, possibly through a hormonal stimulus.