Cytokine response during hyperoxia: sequential production of pulmonary tumor necrosis factor and interleukin-6 in neonatal rats.

BACKGROUND: Exposure of newborn animals to high concentrations of oxygen leads to diffuse alveolar damage similar to that seen in bronchopulmonary dysplasia in human infants. Therefore, neonatal rats are a suitable practical model of hyperoxic lung damage in human infants. OBJECTIVE: To determine the involvement of tumor necrosis factor-alpha and interleukin-6 in lung injury in neonatal rats exposed to 100% O2 concentration. METHODS: A randomized controlled study was designed in which litters of term Sprague-Dawley rat pups were assigned to experimental or control groups. The pups in the experimental group were placed in 100% O2 from birth for 9 days, while the control pups were placed in room air. Twelve to 15 pups from each group were sacrificed on day 1, 3, 6, 9 and 13 after birth for bronchoalveolar lavage collection and lung histologic study. The bronchoalveolar lavage fluid was assayed for TNF alpha and IL-6. RESULTS: Newborn rats exposed to 100% O2 for the first 9 days of life showed severe pulmonary edema and hypercellularity on days 1 and 3, which then improved to nearly complete resolution on days 6 and 9. Pulmonary TNF alpha was produced early on O2 exposure (day 3) and pulmonary IL-6 later (days 6 and 9). CONCLUSIONS: Hyperoxia induces sequential production of pulmonary TNF alpha and IL-6, which corresponds to the severity of the pathological findings and the known inflammatory and anti-inflammatory role of these cytokines.

Superantigens and cystic fibrosis: resistance of presenting cells to dexamethasone.

Staphylococcus aureus, a common pulmonary pathogen in cystic fibrosis (CF), produces exotoxins that are extremely potent superantigens. A number of animal studies have shown that superantigens cause pulmonary inflammation, but the possible role of superantigens in CF has not been investigated. The present study assessed possible differences between control and CF B cells in presenting superantigens to T cells. Immortalized B-cell lines were used as superantigen-presenting cells to avoid environmental influences (e.g., infection or antibiotics) common to freshly isolated cells. The results show that CF B-cell lines presented a staphylococcal superantigen to the immortalized T-cell line (Jurkat) as effectively as did control B-cell lines as measured by interleukin-2 production. However, in contrast to the case for control B-cell lines, dexamethasone did not inhibit CF B-cell lines from presenting superantigen. The resistance of superantigen-presenting CF B cells to corticosteroids suggests that the pulmonary response to superantigens may be poorly regulated in CF, leading to an exaggerated inflammatory response to S. aureus.

MHC class II positive retinal pigment epithelial (RPE) cells can function as antigen-presenting cells for microbial superantigen.

Retinal pigment epithelial (RPE) cells induced to express MHC class II (HLA-DR) by incubation with interferon gamma (IFN-gamma) were investigated for their ability to present a microbial superantigen to T lymphocytes. Superantigens bind to MHC class II antigens and appear to play a role in a number of infectious and autoimmune diseases through stimulation of large numbers of T cells. Primary cultures of human RPE cells treated with IFN-gamma for three days to induce HLA-DR expression bound staphylococcal enterotoxin E (SEE) via HLA-DR and presented SEE to T cells as measured by proliferation of purified peripheral blood T cells and IL-2 synthesis by the Jurkat T cell line. Untreated RPE cells were essentially ineffective as superantigen presenting cells. These results suggest that MHC class II expressing RPE cells could contribute to immune and inflammatory activity in the eye by presenting superantigens to T lymphocytes.

Formation of tight monolayers of guinea pig airway epithelial cells cultured in an air-interface: bioelectric properties.

In this study, we have developed an air-interface culture system in which guinea pig tracheobronchial epithelial (GPTE) cells rapidly form tight monolayers. Enzymatically isolated GPTE cells were plated on collagen-treated polycarbonate microporous cell culture inserts at a density of 10(6) cells/cm2 (day 0). Bioelectric properties of cultures grown in an air-interface were compared with those covered by medium. On day 1 for air-interface cultures, apical fluid was removed and basolateral fluid was replenished. For cultures covered by medium, varying volumes of apical fluid were used. On days 4 and 5 after plating, confluent GPTE monolayers in either liquid-covered or air-interface cultures exhibited similar monolayer resistance values > or = 1.0 kohm-cm2. However, the equivalent short-circuit current (Ieq) was significantly higher in air-interface cultures than those covered with medium on days 4 and 5. The Ieq in air-interface cultures on day 4 was 12.9 microA/cm2. These confluent GPTE cell monolayers cultured in air-interface could be a useful tool for studies of changes in bioelectric and ion transport properties in response to injury and mediators of inflammation.

Ethanol inhibition of signal transduction in superoxide production by rat alveolar macrophages. A proposed mechanism for ethanol related pneumonia.

Alveolar macrophages and neutrophils produce superoxide and other free radicals which are important in killing bacteria. The focus of this paper is the inhibition by ethanol of superoxide production and anti-bacterial activity. The signal transduction pathways leading to superoxide production by phagocytic cells will be reviewed. Our hypothesis is that ethanol alters these signal transduction pathways. Stimulation of superoxide production can be initiated by concanavalin A and phorbol esters. Previously, there were reports by us that ethanol, in vitro, inhibits phorbol ester induced superoxide production in rat alveolar macrophages. Our present report states that concanavalin A induced superoxide production was more sensitive to ethanol inhibition than phorbol ester induced superoxide production. The ethanol induced inhibition of alveolar macrophage superoxide production provides a possible mechanism to explain the increased sensitivity of alcoholics to pneumonia.

A dual role for calcium in regulation of superoxide generation by stimulated rat alveolar macrophages.

Superoxide production in alveolar macrophages is stimulated by agonists which act through Ca2+-mediated (concanavalin A) and/or protein kinase C (phorbol ester or diacylglycerol analogues) -mediated events. Simultaneous addition of saturating concentrations of concanavalin A and a protein kinase C activator (either phorbol 12-myristate-13-acetate or 1-oleoyl-2-acetyl-sn-glycerol) caused a supra-additive enhancement of the initial rate of O2-. production. This synergism closely correlated with the known time-course of Ca2+ mobilization induced by concanavalin A; however, it occurred under conditions in which protein kinase C activation is reportedly not Ca2+ dependent. Phorbol ester-induced O2-. production was partially inhibited by the Ca2+ ionophore, A23187. Although phorbol ester-stimulated O2-. production initially was enhanced by concanavalin A, the duration of this O2-. production was reduced in comparison to that induced by phorbol ester alone. These results suggest a dual role for intracellular Ca2+ in both stimulatory and inhibitory regulation of O2-. production.

Ethanol treatment selectively decreases neutral amino acid transport in cultured hepatocytes.

Primary cultures of adult rat hepatocytes were used to study the effects of 100 mM ethanol on various neutral amino acid transport systems. Ethanol exposure for 24 h selectively decreased amino acid uptake by the A and N systems by 40-70%, but had no significant effect on the ASC and L systems. The decrease in the A system was significant after 3 h of ethanol exposure, and the activity was not affected by the presence or absence of ethanol during the uptake measurements. Kinetic analysis showed that ethanol treatment affected predominantly the high-affinity component of A system activity by decreasing the apparent Vmax without significantly changing the apparent Km. Ethanol treatment did not prevent the cells from increasing A system activity in response to insulin and glucagon, but the magnitude of hormone-stimulated uptake was reduced.

Manipulation of cell-cell and cell-substratum interactions in mouse mammary tumor epithelial cells using broad spectrum antisera.

Two antisera were raised in goats against material shed by two different mammary epithelial cell lines into serum-free culture medium. These antisera, when added to the medium of intact, growing mouse mammary tumor cells in the absence of complement, cause distinct and dramatic alterations in cell morphology and adhesiveness. One antiserum (anti-SFM I) causes mouse mammary tumor epithelial cells to round and detach from the substratum. Treatment with the other antiserum (anti-SFM II) does not affect cell-substratum interactions, but causes the cells to convert from an epitheloid to a fibroblastic morphology. Statistical analysis of transmission electron micrographs of control and antibody-treated cells indicates that treatment with anti-SFM II is associated with a substantial reduction in the extent of intercellular junctions, particularly desmosomes. To identify the components with which the two antisera interact, nonionic detergent extracts of mouse mammary tumor cells were fractionated, and the ability of various fractions to block the morphological effects of either antiserum was determined. The whole Nonidet P40 (NP40) extract of the epithelial cells blocked the effects of both antisera. After the extract was subjected to ion exchange and lectin affinity chromatography, two separate fractions were obtained. One fraction blocks and anti-SFM I induced rounding and detachment of cells from the substratum. The second fraction blocks the effects of both antisera. The isolation of the former fraction, which has highly restricted number of components, represents a significant first step toward identifying the surface membrane molecule(s) involved in cell-substratum adhesion in epithelial cells.

An evaluation of a kinetic acid phosphatase method.

The authors have evaluated a new kinetic acid phosphatase method in which the substrate is alpha-naphthyl phosphate. The original claim that this substrate was highly specific for the prostatic isozyme has been strongly challenged. Therefore, large numbers of patients in the following groupings were included in the evaluation: 52 urology clinic patients, 17 patients with uremia, 11 patients with multiple myeloma and 231 patients who had undergone prostatic biopsies. Two hundred seventy of these patients were found to be free of prostatic cancer. Of these, seven had acid phosphatase values above the upper limit of normal. Five of these seven patients had diagnoses of fibromuscular glandular hyperplasia. One was a woman who had multiple myeloma, and one was a uremic patient. Fifteen of 17 patients who had metastatic cancer of the prostate had elevated acid phosphatase activities, whereas one of 24 patients who had cancer of the prostate but no evidence of metastases had an elevated value.

Structural studies of insulin and insulin derivatives using various immunologic indicators and antibody populations.

These studies suggest that the immunologic indicator in the radioimmune assay, 125I-iodoinsulin, selects antibody populations from within the antiserum that interact with determinants distant from the solvent surface on the insulin molecule to which iodine is substituted. Evidence is presented that the connecting peptide of proinsulin is in close proximity to regions on the solvent surface of the A-chain of insulin that include the tyrosyl residues at A-14 and A-19. A marked immunologic cross-reaction between derivatives of insulin with perturbations in the regions of tyrosyl A-14 and A-19 was noted in the radioimmune assay employing desalanine-(B-30)-desasparagine-(A-21)-insulin antiserum. This observation is consistent with the presence of a restricted population of antibodies in such antisera that is directed toward immunologic determinants in or near the insulin dimer site. The apparent immunologic activity of insulin derivatives depends on which antibody populations from the antiserum pool can react with the immunologic indicatory employed on the one hand and on the composition of antibodies in that antiserum on the other. These studies indicate that the specificity of antibody populations in a given antiserum can be identified and their levels quantitated with several assay systems, each employing one of a variety of indicators.