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Biomedical subjects

B S Polla

Publications and source records attributed to B S Polla.

At least 37 records · Page 2Linked to original sources
PubMed1999

Analysis of hsp70 gene polymorphism in allergic asthma.

BACKGROUND: Allergic asthma is a multifactorial and probably multigenic inflammatory disease of the upper airways, and has been associated with the HLA class II alleles DR4 and DR7. Here we investigated possible associations with other polymorphic susceptibility/resistance genes located within the major histocompatibility complex, i.e., the genes coding the major 70-kDa heat-shock proteins (HSP; Hsp70) hsp70-1, hsp70-2, and hsp70-HOM, whose products are overexpressed in the bronchi of asthmatic patients. METHODS: Genomic DNA was extracted from peripheral blood lymphocytes or buccal epithelial cells of 48 patients with allergic asthma and 31 selected nonatopic control subjects, in whom we previously reported a strong association of atopy with DR4/DR7 alleles. RESULTS: No evidence was found for an independent role of hsp70 gene polymorphism in susceptibility to allergic asthma. However, hsp70 alleles might be involved in extended haplotypes of HLA markers. CONCLUSIONS: Our data suggest that Hsp70 overexpression in asthma results from complex interactions between environmental exposures and genetic background rather than from specific genetic variations in hsp70 genes.

Adult↗
PubMed1999

HLA class II polymorphism in cystic fibrosis. A possible modifier of pulmonary phenotype.

Evolution of lung damage is highly variable in cystic fibrosis (CF) even in patients with the same cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The analysis of genetic factors other than CFTR may help our understanding of genotype-phenotype relationships in CF. As human leukocyte antigen (HLA) class II polymorphism has been associated with a number of diseases including autoimmune and inflammatory diseases, asthma, and allergy, we investigated the possibility that HLA polymorphism contributes to CF-associated pulmonary inflammation. Among the 98 adult CF patients tested, the genotypic frequencies of DR4 and DR7 alleles (serologic group DR53) and DR7/ DQA*0201 haplotype were higher than in 39 selected control subjects without atopy (p </= 10(-)6, relative risk [RR] = 22, and p </= 5.10(-)4, RR = 27, respectively) and in a random population. No significant difference of these allelic distributions was found according to the CFTR genotype. In the CF patients, the DR7 allele was significantly associated with an increase in total IgE and with chronic Pseudomonas aeruginosa colonization (100% of DR7 versus 83% of non-DR7 patients being colonized, p < 0.05). Our results suggest that genetic factors known to modulate the immune response might contribute to chronic infection with Pseudomonas, increased total IgE, and pulmonary outcome in CF.

Adult↗
PubMed1999

Tobacco smoke induces mitochondrial depolarization along with cell death: effects of antioxidants.

Smoking has been associated with a large number of diseases, in particular cancers. Among the many substances identified in tobacco smoke, reactive oxygen species (ROS) are major carcinogens. We have previously reported that exposure of mammalian cells to tobacco smoke induces the expression of stress proteins, as well as apoptosis (programmed cell death). Here we examined the effects of tobacco smoke on mitochondrial membrane potential (deltapsim), since mitochondria have been proposed to control the effector phase of apoptosis. We used normal human monocytes for these experiments, with the prospect for application of deltapsim as a biomarker of oxidative stress. Tobacco smoke induced mitochondrial depolarization at 3 h, and apoptosis (or necrosis for higher concentrations) after 16 h. Apoptosis was assessed by both a functional approach (annexin V binding) and morphological analysis (electron microscopy). N-acetyl-cysteine prevented tobacco smoke-induced deltapsim disruption and apoptosis, while the caspase inhibitor Z-VAD.Fmk did not affect deltapsim, though preventing apoptosis, and superoxide dismutase had no effect. Our data designate mitochondria as a target for ROS-mediated effects of tobacco smoke exposure.

Acetylcysteine↗
PubMed1999

Heat shock protein 70 and ATP as partners in cell homeostasis (Review).

Heat shock proteins (HSP) are molecular chaperones, involved in many cellular functions such as protein folding, transport, maturation and degradation. Since they control the quality of newly synthesized proteins, HSP take part in cellular homeostasis. The Hsp70 family in particular exerts these functions in an adenosine triphosphate (ATP)-dependent manner. ATP is the main energy source used by cells to assume fundamental functions (respiration, proliferation, differentiation, apoptosis). Therefore, ATP levels have to be adapted to the requirements of the cells and ATP generation must constantly compensate ATP consumption. Nevertheless, under particular stress conditions, ATP levels decrease, threatening cell homeostasis and integrity. Cells have developed adaptive and protective mechanisms, among which Hsp70 synthesis and overexpression. In this review, we focus on the mechanisms which regulate Hsp70 expression under ATP depletion, using ischaemia as a paradigmatic model for ATP depletion in vivo, and analyze the molecular targets for Hsp70-mediated protection against ATP depletion. We also consider how these Hsp70-mediated protective effects could be applied in the therapeutical approaches of human diseases associated with cellular ATP depletion.

Adenosine Triphosphate↗
PubMed1998

Tobacco smoke induces coordinate activation of HSF and inhibition of NFkappaB in human monocytes: effects on TNFalpha release.

Tobacco smoke (TS) exposure is a major risk factor for human disease, and macrophages of healthy smokers have a depressed capacity to release cytokines, including tumor necrosis factor (TNF)alpha. TS induces the synthesis of heat shock (HS)/stress proteins (HSP), and, in particular, of Hsp70. We determined whether Hsp70 induction by TS was mediated by the activation of the HS transcription factor, HSF. HSF activation has been shown to inhibit NFkappaB. Thus, we also determined the effects of TS on NFkappaB. U937 cells and human peripheral blood monocytes were exposed to TS, binding activities of the respective transcription factors were analyzed, and Hsp70 expression and TNFalpha release were determined in parallel. TS activated HSF, which was associated with Hsp70 overexpression and inhibition of NFkappaB binding activity and TNFalpha release. The altered cytokine profile observed in smokers may relate to an HSF/Hsp70-mediated inhibition of NFkappaB activity.

DNA-Binding Proteins↗
PubMed1998

Effects of iron deprivation on the pathology and stress protein expression in murine X-linked muscular dystrophy.

Duchenne muscular dystrophy (DMD) is caused by dystrophin deficiency, which results in muscle necrosis and the upregulation of heat shock/stress proteins (HSP). We hypothesized that reactive oxygen species, and in particular hydroxyl radicals (.OH), participate in muscle necrosis and HSP expression. It was assumed that iron deprivation decreases .OH generation, restraining the disease process and reducing the oxidant-induced expression of HSP. The role of iron-catalyzed free radical reactions in the pathology of dystrophin-deficient muscle was evaluated in the murine model for Duchenne muscular dystrophy (mdx), by examining the effects of dietary deficiency and supplementation of iron on serum creatine kinase (CK), muscle morphology, lipid peroxidation and HSP levels in mice maintained on diets deficient in or supplemented with iron for 6 weeks. Iron-deprived mdx mice showed a significant decrease in the number of macrophage-invaded necrotic fibers and the expression of the 70-kDa heat shock protein (Hsp70). This suggests that the iron-dependent generation of .OH relates to muscle necrosis in the mdx mouse and modulates the expression of Hsp70 in vivo. In contrast, iron deprivation had no influence on other HSP or on lipid peroxidation in mdx mice, while maintenance on either diet caused a significant decrease in serum creatine kinase activity. The potential therapeutic effects of iron deprivation in mdx should be considered.

Animals↗
PubMed1998

In vivo heat shock protects rat myocardial mitochondria.

Heat shock (HS)/stress proteins (HSP) provide protection from a variety of stresses other than HS, including oxidative stress and mitochondria have been implicated as the target of HS-related protection in stressed cultured cells. Here we investigated whether mitochondria also are targets for the HS-mediated protection in vivo. Sprague Dawley rats were exposed, or not, to HS (41 degrees C, 15 min). After a 21 h recovery period, hearts were excised and perfused with or without H2O2 (0.15 mM). Myocardial mitochondria were then isolated, and their oxygen consumption was analyzed. HS prevented H2O2-induced alterations in state 3 respiration while increasing the expression of Hsp70 and heme oxygenase (HO). Thus, in vivo HS protects rat myocardial mitochondrial respiration against the deleterious effects of oxidative injury, a protection relating to Hsp70 and/or HO and targeting state 3 respiration.

Animals↗
PubMed1998

Gamma-ray irradiation induces B7.1 costimulatory molecule neoexpression in various murine tumor cells.

The use of gene-modified tumor cells as a strategy for active immunotherapy is currently undergoing intensive fundamental and clinical research. Most clinical trials use gamma-ray-irradiated tumor cells as vaccine, although little is known about the effects of irradiation on the immunogenicity of tumor cells. In particular, no data have been reported so far concerning the effects of gamma-ray irradiation on the expression of B7 molecules in tumor cells. In this paper, we show a neoexpression of the B7.1 molecule after gamma-ray irradiation in tumor cell lines from different tissues, while the B7.2 molecule remains unexpressed in all the cell lines tested. Furthermore, the induction of B7.1 molecule membrane expression after irradiation is shown to result from the neoexpression of B7.1 mRNA, and to be reproduced with H2O2 oxidative stress. These data could explain the enhanced immunogenicity of many tumor cells after irradiation, and could lead to new immunotherapy protocols.

Animals↗
PubMed1998

Tobacco smoke induces both apoptosis and necrosis in mammalian cells: differential effects of HSP70.

Tobacco smoke (TS) has been implicated as a major risk factor in human pulmonary diseases including cancer. In this study, we used TS as a model of oxidative stress. TS-mediated oxidative stress has been shown to induce protein oxidation, DNA damage, and cell death. Here we investigated, in human and rodent cell lines, whether TS induces cell death by apoptosis or by necrosis. As described for classic oxidants, TS induced apoptosis at low concentrations and necrosis at higher concentrations. We have previously described the induction of heat shock (HS) protein (HSP) (in particular, HSP70) in human monocytes exposed to TS. HSP70 is implicated in the regulation of cell injury and cell death and, in particular, modulates apoptosis, as does the antiapoptotic oncoprotein Bcl-2. At both apoptotic and necrotic concentrations, TS induced a dose-dependent HSP70 expression, whereas Bcl-2 was induced only at necrotic concentrations. TS- or HS-induced HSP had no protective effects either on apoptosis or on necrosis, but HSP70 overexpression prevented TS-induced necrosis and consequently led to increased apoptosis. These results might reconcile the apparently contradictory data previously reported on the effects of HSP on apoptosis.

Animals↗
PubMed1998

Stress symposium in Johannesburg: plants versus humans.

On 18 February 1998, a 'Stress symposium' was held at the Rand Afrikaans University (RAU) in Johannesburg, South Africa. The meeting brought together people from both the plant and the human oxidative stress field, which was exemplified by a talk entitled 'Heat shock proteins in host-pathogen interactions: plants versus humans'. There were moments when it appeared as if the main difference between plants and humans was, as sung by Julos Beaucarne, that 'the human plant is the only one to be able to water itself...'

Animals↗
PubMed1998

Flow cytometry is a rapid and reliable method for evaluating heat shock protein 70 expression in human monocytes.

The increasing interest in stress/heat shock proteins (Hsps) as markers of exposure to environmental stress or disease requires an easily applicable method for Hsp determination in peripheral blood cells. Of these cells, monocytes preferentially express Hsps upon stress. An appropriate fixation/permeabilization procedure was developed, combined with immunofluorescence staining and flow cytometry for the detection of the inducible, cytosolic, 72 kDa Hsp (Hsp70) in human monocytes. Higher relative fluorescence intensity was observed in cells exposed to heat shock (HS), reflecting a higher expression of Hsp70 in these cells as compared with cells kept at 37 degrees C. The heat-inducible increased Hsp70 expression was temperature- and time-dependent. Expression of Hsp70 was not uniform within the monocyte population, indicating the presence of subpopulations expressing variable levels of Hsp70 in response to HS. Simultaneous measurements of intracellular Hsp70 and membrane CD14 expression revealed that the higher Hsp70 inducibility coincided with the higher CD14 expression. Comparisons performed with biometabolic labelling, Western blotting, immunofluorescence and immunoperoxidase microscopic analysis, showed a high concordance between these different methods; however, cytometry was more sensitive for Hsp70 detection than Western blotting. Flow cytometric detection of intracellular Hsp70 is a rapid, easy and quantitative method, particularly suited for the determination of protein levels in individual cells from an heterogeneous population such as peripheral mononuclear blood cells, and applicable to cohort studies.

Blotting, Western↗
PubMed1997

Effects of membrane fatty acids on thermal and oxidative injury in the human premonocytic line U937.

Heat shock (HS) proteins (HSP) function as molecular chaperones and protect cells from thermal and oxidative injury. The signals leading to HSP synthesis, i.e. the "cellular thermometer(s)," are still a matter of debate. In the human premonocytic line U937, we investigated the effects of specific modification of membrane fatty acid (FA) composition by incubation with various saturated and unsaturated fatty acids (UFA) on the HS response and on hydrogen peroxide (H2O2)-induced cell death. FA readily incorporated into U937 cell membranes. UFA did not modulate the HS response but potentiated H2O2-mediated damage, while pre-exposure to HS protected the UFA-treated cells from this increased H2O2 toxicity.

Calcium↗
PubMed1997

Heat shock and proinflammatory stressors induce differential localization of heat shock proteins in human monocytes.

Heat shock (HS) proteins (HSP) are a family of molecular chaperones induced by environmental stresses such as oxidative injury, and contribute to protection from and adaptation to cellular stress. We investigated in human monocytes the expression and subcellular distribution of hsp70 and hsc70 after HS and inflammation-related stresses leading to generation of reactive oxygen species by these cells, such as the phorbol ester PMA and erythrophagocytosis (E phi). By combining immunofluorescent staining and Western blot on subcellular fractions, we found that all three stress factors resulted in an increased hsp70 expression, however the subcellular distribution pattern was different depending on the type of stress. While HS induced a rapid translocation of hsp70 into the nucleus, no nuclear translocation of hsp70 was observed after PMA or E phi. Neither of the examined stresses induced membrane expression of hsp70. The observed differences in subcellular distribution pattern might relate to distinct regulation and specific functions of hsp70 in inflammation.

Biological Transport↗
PubMed1997

Modified natural porcine surfactant inhibits superoxide anions and proinflammatory mediators released by resting and stimulated human monocytes.

Pulmonary surfactant has a potential role in modulating inflammation in normal and injured lungs. In lung injury, monocytes become activated and participate in lung inflammation. We therefore, investigated the proinflammatory functions of stimulated human blood monocytes after an overnight preincubation period with modified natural porcine surfactant (Curosurf) (500-1000 micrograms/mL). Monocytes were stimulated either with phorbol myristate acetate (PMA), bacterial extract OM-85, lipopolysaccharide (LPS), or Ca2+ ionophore A23187. The present study shows that Curosurf significantly inhibits: 1) the production of superoxide anions stimulated with OM-85 (1 mg/mL, 30 min), but not with PMA (100 ng/mL, 30 min); 2) the release of cyclooxygenase metabolites prostaglandin E2 and thromboxane B2 stimulated with OM-85 (1 mg/mL, overnight); 3) the release of lipoxygenase metabolite leukotriene C4 stimulated with A23187 (10 microM, 10 min); 4) the release of the cytokine TNF-alpha stimulated overnight with either OM-85 (1 mg/mL) or LPS (10 micrograms/mL)) in a dose-dependent fashion. In addition, Curosurf decreases the spontaneous adherence of monocytes to plastic culture wells in a dose-dependent fashion. Experiments performed with staurosporine, an inhibitor of protein kinase C (PKC) indicate that, in contrast with PMA, the production of superoxide anions stimulated by OM-85 is not related to PKC activation. Consequently, we propose that the mechanism involved in the suppressive effects of Curosurf is PKC-independent. In summary, the present study provides experimental evidence that favors the anti-inflammatory role of modified natural porcine surfactant (Curosurf) in human monocytes in vitro.

Adjuvants, Immunologic↗