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.
To determine the involvement of tumor necrosis factor-alpha and interleukin-6 in lung injury in neonatal rats exposed to 100% O2 concentration.
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.
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).
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.
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.
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.
In order to obtain a better understanding of immune system function in chronic alcoholism, we have assessed primary B-cell responses to helper T-cell independent (TI) and dependent (TD) antigens in ...chronic alcoholic Sprague-Dawley male rats fed totally liquid diet containing ethanol. Pair-fed littermates received the same diet except that carbohydrates isocalorically replaced ethanol, which accounted for 36% of the total calories. The ability of alcoholic animals to mount primary in vivo splenic plaque-forming cell (PFC) responses to TI pneumococcal polysaccharide type III (SIII) was elevated throughout 50 days of observation when compared to pair-fed controls; serum antibody responses to SIII paralleled the enhanced PFC responses. Primary in vivo B-cell responses to antigen sheep red blood cells (SRBC), a TD antigen, were initially elevated but were found to be significantly suppressed 30 days after chronic ethanol consumption. The degree of immunosuppression increased with length of chronic ethanol consumption. The elevated primary splenic PFC responses to TI (SIII) may be attributed to loss of T-suppressor cell control, since alcoholic rat spleen cells did not respond to low-dose priming with SIII. We suggest that either loss of function and/or actual depletion of accessory and regulatory cells (T-suppressor and T-helper) may be responsible for irregularities in B-cell function observed during chronic alcoholism. T-cell subset enumeration using fluorescein-labelled monoclonal antibodies revealed that a sequential T-helper and T-suppressor loss occurred several days following dysfunction of these T-cell subsets in splenic populations, suggesting that a combination of numerical and dysfunctional changes in lymphocyte subpopulations may be responsible for the immunological alterations observed in chronic alcoholics.
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.
Retinal pigment epithelial (RPE) cells induced to express MHC class II (HLA-DR) by incubation with interferon gamma (IFN-α) 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-α 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.
Superoxide production in alveolar macrophages is stimulated by agonists which act through Ca
2+-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 O
⨪
2 production. This synergism closely correlated with the known time-course of Ca
2+ mobilization induced by concanavalin A; however, it occurred under conditions in which protein kinase C activation is reportedly not Ca
2+ dependent. Phorbol ester-induced O
⨪
2 production was partially inhibited by the Ca
2+ ionophore, A23187. Although phorbol ester-stimulated O
⨪
2 production initially was enhanced by concanavalin A, the duration of this O
⨪
2 production was reduced in comparison to that induced by phorbol ester alone. These results suggest a dual role for intracellular Ca
2+ in both stimulatory and inhibitory regulation of O
⨪
2 production.
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.
PDF
