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Biomedical subjects

B S Polla

Publications and source records attributed to B S Polla.

At least 73 records · Page 4Linked to original sources
PubMed1995

Differential induction of stress proteins and functional effects of heat shock in human phagocytes.

Induction of specific heat shock (HS) proteins (HSP) has been described as a response of human monocytes to phagocytosis, and HSP may play protective roles in infection and immunity. Here we compared the stress response in monocytes and polymorphonuclear neutrophils during exposure to the classical inducers of HSP, i.e., HS and cadmium. We also investigated the stress response in these two phagocytic cells after particulate (phagocytosis) and nonparticulate [f-Met-Leu-Phe (FMLP)] activation of the respiratory burst enzyme NADPH oxidase. HS and cadmium induced stress protein synthesis in both cell types. In contrast, phagocytosis induced HSP in monocytes only, while FMLP did so in neutrophils only. This differential regulation of stress proteins might relate to physiological and functional differences between monocytes and neutrophils. With respect to functional effects of HS, we examined, in human monocytes and in neutrophils, the effect of HS on NADPH oxidase-mediated O2- generation as well as on phagocytosis, bacterial killing, and superoxide dismutase (SOD) activity. In monocytes, as in neutrophils, NADPH oxidase activity was inhibited by HS, while thermotolerance prevented this inhibition. Phagocytosis and bacterial killing were unaltered by HS. SOD activity transiently increased in monocytes but decreased in neutrophils upon exposure to HS. These observations indicate differential induction of HSP in human phagocytes and differential regulation of phagocytes' functions by HS.

Cadmium↗
PubMed1995

In vitro lymphocyte proliferation with milk and a casein-whey protein hydrolyzed formula in children with cow's milk allergy.

Discordant results have been reported about the role of lymphocyte proliferation assays in patients with cow's milk allergy. We studied the peripheral blood mononuclear cell response of 10 children with cow's milk allergy by means of a lymphocyte proliferation test to determine the diagnostic value of this assay, the clinical tolerance of a new therapeutic hydrolyzed formula, and the evolution of lymphocyte proliferation after 3 months of a cow's milk-free diet with the hydrolyzed formula. The lymphocyte proliferation at the time of diagnosis in the patients with cow's milk allergy was not statistically different from the results in the control group. The proliferation test performed after 3 months of diet with the hydrolyzed formula and restriction of cow's milk protein showed that the cellular proliferation remained globally the same compared with the proliferation at the time of diagnosis. The hydrolyzed formula proteins induced a lower cellular proliferation than milk proteins in patients with cow's milk allergy. Our results suggest that the lymphocyte proliferation test cannot be recommended for diagnostic purposes. However, in patients with cow's milk allergy the proliferation test affirmed the absence of immunogenicity of the hydrolyzed formula because it induced no significant T-cell activation.

Animals↗
PubMed1995

Heat-shock proteins in host-pathogen interactions: implications for cystic fibrosis.

The expression of heat-shock proteins by both pathogen and host cells during the phagocytosis of Staphylococcus aureus and Pseudomonas aeruginosa, two bacterial species that colonize the airways of patients with cystic fibrosis, probably contributes to pulmonary inflammation in cystic fibrosis. Here, we discuss the likely signals for heat-shock-protein induction within host and bacterial cells.

Bacterial Proteins↗
PubMed1995

Infection of human and murine macrophages with Leishmania major is associated with early parasite heat shock protein synthesis but fails to induce a host cell stress response.

Heat shock/stress proteins (HSP) represent the most conserved proteins expressed in prokaryotes and eukaryotes. These constitutive and inducible proteins function as molecular chaperones and are part of virulence factors. They participate in self/non-self discrimination and may protect phagocytes from the toxic effects of the reactive oxygen species generated by these cells during bacterial phagocytosis and infection. In this study, we investigated the early stress response of host cells [either human alveolar macrophages (AM) or murine peritoneal macrophages (PM)] during infection by an obligate intracellular parasite (Leishmania major), which lives within phagolysosomes. Immunoblotting with specific antibodies demonstrated that L. major had no effect on host stress protein synthesis, but synthesized high levels of its own stress proteins within AM and PM. The lack of induction of a host cell stress response may relate to the failure of L. major to activate the respiratory burst in these cells, whereas the upshift of L. major HSP within macrophages is part of an adaptive response of the parasite to the host.

Animals↗
PubMed1995

Serological evidence of Aspergillus type I hypersensitivity in a subgroup of pulmonary aspergilloma patients.

Aspergillus causes a spectrum of diseases, among which aspergilloma (saprophytic colonization) and allergic bronchopulmonary aspergillosis (ABPA). We investigated the possible presence of type I hypersensitivity in patients with aspergilloma (as is classically found in ABPA). The sera of 38 patients with aspergilloma were investigated for the presence of Aspergillus-specific IgE by the CAP System (CAP) and by the RAST System (RAST). Twelve of these patients (32%) showed positive Aspergillus-specific IgE (group ASP-IgE+), with the CAP being more sensitive than the RAST. Median total IgE was higher in the ASP-IgE+ group as compared with the ASP-IgE- f1p4p (p < 0.05), but no differences were seen between the ASP-IgE+ group and patients with ABPA. Furthermore, when Alternaria-specific IgE were compared between ASP-IgE+ and ABPA groups, they were found more frequently in the latter group (p < 0.05). Thus, an aspergilloma group with type I hypersensitivity was isolated whose serologic profile to Aspergillus antigens was similar to the ABPA group. However, the patients in this group did not show sensitization to another mould (i.e., Alternaria), in contrast to the ABPA group. The presence of type I hypersensitivity in a subgroup of aspergillomas suggests an immunoallergic component to this disease which could contribute to a chronic inflammatory response to Aspergillus in some aspergillomas.

Adult↗
PubMed1995

Increased expression of heat shock protein 70 on airway cells in asthma and chronic bronchitis.

Heat shock proteins (HSPs) appear to be involved in inflammation. Because asthma is an inflammatory disease, HSPs may be expressed. We studied the expression of HSP-70 by immunohistochemistry using the alkaline-phosphatase anti-alkaline phosphatase technique on epithelial cells and alveolar macrophages (AMs) from 19 patients with asthma, eight patients with chronic bronchitis (CB), and 13 control subjects and in bronchial biopsies from 15 asthmatics, 15 CB patients, and nine control subjects. The specificity of the antibody was confirmed by Western blotting on heated AM. The specificity of the immunostaining was confirmed by inhibition experiments. The expression of HSPs in the asthmatics in comparison with the CB patients and control subjects was significantly increased on epithelial cells (P < 0.002 and P < 0.007, respectively) and AMs (P < 0.0004 and P < 0.0002, respectively) and was significantly correlated with the severity of asthma (P < 0.005 for AMs) and the percentage of eosinophils in bronchoalveolar lavage fluid (P < 0.004). In biopsies from the asthmatics but not from the CB patients or control subjects, a positive staining for HSP-70 was observed on epithelium, mononuclear cells, and basement membrane and was correlated with the severity of asthma (P < 0.0005, P < 0.002, and P < 0.007, respectively). This study demonstrates that bronchial inflammation in asthma but not in CB may be linked to the production of HSPs.

Adult↗
PubMed1994

Protective effects of hsp70 in inflammation.

Inflammation results from the recruitment to a given tissue or organ and the activation of leucocytes, among which the monocytes-macrophages play a major role. These phagocytic cells produce high levels of reactive oxygen species (ROS) as well as cytokines. Whereas both ROS and cytokines have the potential to regulate the expression of heat shock (HS)/stress proteins (HSP), it appears that these proteins in turn have the ability to protect cells and tissues from the deleterious effects of inflammation. The mechanisms by which such protection occurs include prevention of ROS-induced DNA strand breaks and lipid peroxidation as well as protection from mitochondrial structure and function. In vivo, HS protects organs against a number of lesions associated with the increased production of ROS and/or cytokines. In an animal model for adult respiratory distress syndrome, an acute pulmonary inflammatory condition, HS completely prevented mortality. HSP (hsp70 in particular) may also exert protective effects in the immune system by contributing to the processing and presentation of bacterial and tumoral antigens. The analysis of the expression of hsp70 may prove of diagnostic and prognostic value in inflammatory conditions and therapeutical applications are being considered.

Animals↗
PubMed1994

cAMP modulates stress protein synthesis in human monocytes-macrophages.

The synthesis of heat-shock proteins (HSPs) and other stress proteins, including heme oxygenase (HO) and ferritin, is differentially induced by heat and oxidizing agents. In order to determine what role cAMP plays in those inductions in human monocytes-macrophages (m phi), we used cAMP activators or analogues alone or in combination with various stressful conditions. A stimulation in cAMP production did not per se affect stress proteins synthesis in m phi but modulated their induction in a differential way according to the stimulus. cAMP increased the synthesis of HSPs after heat shock. During erythrophagocytosis, whereas cAMP depressed the phagocytic process and the associated generation of superoxide anions, it enhanced the synthesis of HSPs, while inhibiting that of HO and ferritin. These results indicate that cAMP has a direct enhancing effect on the expression of stress proteins controlled by a classic heat-shock promoter, while decreasing their expression when induced by oxidative stress.

Cadmium↗
PubMed1994

DNA damage and stress protein synthesis induced by oxidative stress proceed independently in the human premonocytic line U937.

Heat shock proteins (HSPs) function as stress-inducible molecular chaperones and exert protective effects against cellular injury. The induction of the HSPs is considered to be mediated by the presence of abnormal proteins within the cell and/or by classical second messengers. Several lines of evidence have however suggested a relationship between DNA damage, HSP induction and thermotolerance. We investigated whether DNA alterations could represent a common signal for the induction of stress protein synthesis during heat shock or exposure to reactive oxygen species in the human premonocytic line U937. We measured, in parallel, DNA damage (both strand breaks and fragmentation) and HSP synthesis (by biometabolic labeling and Western blotting) after exposure to heat shock, hydrogen peroxide, bleomycin, cadmium or erythrophagocytosis. Heat shock induced DNA alterations along with HSP synthesis. In contrast, exposure to hydrogen peroxide or bleomycin induced DNA damage, but no HSP synthesis, suggesting that oxidation-induced DNA damage and HSP synthesis proceed independently in U937 cells. Erythrophagocytosis and cadmium induced the classical HSPs but no detectable DNA damage. Since these latter stresses also induced the oxidation-specific stress protein heme oxygenase, we suggest a protective role for heme oxygenase against oxidative DNA damage.

Bleomycin↗
PubMed1994

Exposure of monocytes to heat shock does not increase class II expression but modulates antigen-dependent T cell responses.

Expression of heat shock (HS) proteins (HSP) increases after exposure to elevated temperatures or other types of injury, such as oxidative injury. Because of their function as 'molecular chaperones', HSP are suggested to participate in antigen processing and presentation. We have previously reported that HS modulates antigen presentation in a human EBV-transformed B cell line. Here we investigated the effects of HS on MHC class II expression and on antigen processing and presentation by human monocytes. Monocytes were isolated from peripheral blood of normal human volunteers, purified by adherence, then exposed to temperatures ranging from 37 to 45 degrees C for 20 min, allowed to recover for 2 h at 37 degrees C and used for immunofluorescence or as antigen presenting cells in autologous and heterologous lymphocyte proliferation assays. No increase in class II expression was detected as assessed by flow cytometry. Monocytes (3 x 10(4)) and lymphocytes (1 x 10(5)) were co-cultured for 5 days in the presence of several antigens [diphtheria toxoid, tetanus toxoid or purified peptide derivative (PPD)] and labeled with 1 microCi [3H]thymidine for 16 h. Pre-exposure to HS (44 degrees C) significantly (P < 0.001) increased T cell responses to diphtheria toxoid, whereas the effect on the responses to other antigens (tetanus toxoid or PPD) were not significant. HS did not increase heterologous T cell responses nor T cell proliferation induced by the non-processed superantigens such as staphylococcal enterotoxin B. The effect of HS was inhibited by actinomycin B and thus appeared dependent upon HSP synthesis. HSP-mediated increases in antigen processing may potentiate the ongoing immune response at inflammatory sites.

Antigen Presentation↗
PubMed1994

Specificity of antibodies induced after immunization of mice with the mycobacterial heat shock protein of 65 kD.

We have previously shown in mice and monkeys that mycobacterial heat shock proteins (hsp) of 65 and 70 kD exert a strong in vivo helper effect when conjugated to synthetic peptides or bacterial oligosaccharides and given in the absence of any adjuvants. Considering the degree of homology existing in the phylogeny among hsp belonging to the same family, we studied whether antibodies induced in mice with this protocol of immunization with the mycobacterial 65-kD hsp (hsp65) would cross-react, and to what extent, with hsp homologues from other origins, notably with the Escherichia coli GroEL protein and with the human homologue (hsp60). The results obtained show that antibodies to the mycobacterial hsp65 cross-reacted with the E. coli GroEL protein, both in ELISA and Western blot experiments, but not with the human hsp60. In competitive ELISA experiments, the binding of these antibodies to solid-phase hsp65 was very effectively inhibited by low concentrations of the mycobacterial hsp65; however, for human hsp60, 100 times higher concentrations were required in order to obtain similar patterns of inhibition. Finally, murine antibodies to the mycobacterial hsp65 always failed to give positive results in Western blot experiments using extracts of murine cells. Taken together, these data suggest that, after immunization of mice with the mycobacterial hsp65 conjugated to peptides or oligosaccharides in the absence of adjuvants, anti-hsp65 antibodies are induced which cross-react well with hsp homologues from other prokaryotes (e.g. E. coli GroEL), but which weakly bind the human hsp homologue. These results may have implications for the potential use of microbial hsp molecules in the design of conjugated vaccine constructs.

Animals↗
PubMed1994

Oxygen metabolites from lavage and interstitial lung cells after inhalation of endotoxin in guinea pigs.

Airborne endotoxins play a role in a variety of occupational diseases such as byssinosis and humidifier's disease and are associated with pulmonary and systemic symptoms. An excess generation of oxygen free radicals (including superoxide anion, O2-) by inflammatory cells has been suggested in endotoxemia. We have studied the release of superoxide from guinea-pig lung lavage and interstitial cells and blood monocytes (BMs) at different times after an acute inhalation exposure to bacterial endotoxin. O2- generation was measured by the O2- dismutase-inhibitable reduction of ferricytochrome c, after stimulation with phorbol-myristate-acetate (PMA) or opsonized zymosan (OZ). After endotoxin exposure, the spontaneous release of O2- remained unchanged for the three cell types. From 4 h after exposure until 48 h afterwards, lung lavage cells produced more O2- after PMA or OZ stimulation than did cells from unexposed guinea pigs. The pattern of O2- generation by interstitial cells followed that of lung lavage macrophages. O2- production remained unchanged in BMs at all times. These results suggest that endotoxin inhalation induced a priming of lavage and interstitial cells, mainly macrophages, associated with an increase in O2- production. As O2- production by BMs remained unchanged, this cell is unlikely to be responsible for the systemic symptoms seen after endotoxin inhalation.

Administration, Inhalation↗
PubMed1994

Heat shock proteins and the kidney.

The heat shock (HS) response is remarkably conserved during evolution and is evoked under many conditions of stress. There are a number of ways in which this ubiquitous response may be important for the understanding of renal pathophysiology. Ischemia, toxin exposure, and oxidative stress induce this response. Several models of hypertension are associated with increased susceptibility to environmental stress and increased accumulation of heat shock protein mRNA. HSP70 polymorphism has been demonstrated when comparing normotensive and hypertensive rats. Heat shock proteins may play a role in renal diseases through their important involvement in immunological processes. Several observations point to a role of the heat shock response in systemic lupus erythematosus (SLE). Autoantibodies against HSP70 and ubiquitin are found in many patients with this disease. Autoantibodies against ubiquitin and ubiquitinated histone H2A are localized to the kidney glomerular basement membrane of SLE patients with active disease. A better understanding of the HS response may thus provide important insight into renal pathophysiology and may suggest paradigms for therapeutic interventions.

Adult↗
PubMed1993

Heat shock in human neutrophils: superoxide generation is inhibited by a mechanism distinct from heat-denaturation of NADPH oxidase and is protected by heat shock proteins in thermotolerant cells.

Independently of the stimulating agent used, generation of O2- by human neutrophils is transiently inhibited when the cells have been exposed to elevated temperatures. This phenomenon is concomitant with the synthesis of heat shock proteins (HSPs). We have investigated a possible relationship between HSPs and modulation of NADPH oxidase activity in human neutrophils exposed to heat. HSPs were not involved in the inhibition of O2- generation since 1) in enucleated cytoplasts, which are unable to synthesize proteins, the generation of O2- was inhibited after exposure to 43 degrees C, 2) using actinomycin D (Act D) in intact cells, it was possible selectively to inhibit the synthesis of HSPs without modifying the inhibition of NADPH oxidase activity that followed HS. Furthermore, the recovery of NADPH oxidase activity was not under the control of HSPs because the enzyme recovered as well in Act D-treated neutrophils. The NADPH oxidase activity was reconstituted in a cell-free assay by combining the cytosol with the plasma membrane-enriched fraction in the presence of arachidonic acid (AA) and NADPH. Subcellular fractions obtained from control or heated neutrophils exhibited similar oxidase activities suggesting that heat exposure did not induce denaturation of the oxidase components but rather altered the mechanisms of translocation and/or assembly of these components with the plasma membrane. This hypothesis was supported by the inhibition of the granule release in heated cells, a process which also requires translocation and association fusion with the plasma membrane. On the other hand, preexposure of neutrophils to HS prevented the inhibition of O2- generation during a second challenging HS. This acquired thermotolerance was abolished when the synthesis of HSPs was inhibited during the first HS with Act D, indicating a direct relationship between protection of O2- generation and synthesis of HSP. Here we demonstrate that synthesis of HSPs and inhibition or recovery of NADPH oxidase activity are concomitant but unrelated phenomena. In contrast, accumulation of HSPs in thermotolerant neutrophils appeared to play an important role in the prevention of NADPH oxidase inhibition. These results provide further insights into the behavior of human neutrophils and NADPH oxidase upon heat injury.

Cell Degranulation↗
PubMed1993

Fluorodeoxyglucose cell incorporation as an index of cell proliferation: evaluation of accuracy in cell culture.

The use of fluorodeoxyglucose (FDG) and positron emission tomography (PET) is recognized as an accurate tool for the specific diagnosis and staging of cancer. It has also been proposed for the monitoring of anticancer therapy. FDG cell incorporation reflects glycolytic activity whereas inhibition of cell proliferation corresponds to an efficient cancer treatment. The relationship between FDG incorporation and cell proliferation has yet to be demonstrated. Therefore, we aimed to correlate the effects of the toxic agents bleomycin and unlabelled meta-iodobenzylguanidine (mIBG) on cellular metabolism and proliferation. We determined the in vitro metabolic and cytotoxic effects of bleomycin and mIBG by measuring the incorporation of fluorine-18 FDG (%UFDG) and hydrogen-3 thymidine (%UTHY) in cells of the human premonocytic line U937 in the presence of increasing concentrations of these agents. Proliferation rate of these cells was studied by means of limiting dilution analysis. %UTHY appeared more sensitive to bleomycin or mIBG-mediated cell injury than %UFDG. After 1 h of exposure to 0.5 microM bleomycin, %UTHY was significantly reduced to 62.0% +/- 10.4% of control value whereas %UFDG remained unchanged (91.6% +/- 5.3%). Similar results were obtained after 1 h of exposure to increasing concentrations of mIBG (1 microM to 1 mM). After 20 h of exposure to bleomycin, %UTHY and %UFDG were significantly reduced as a function of concentration. After 20 h of exposure to mIBG, a transient increase in %UFDG up to 149.3% +/- 11.2% with 50 microM mIBG was further followed by a reduction to 20.1% +/- 6.7% with 0.5 mM (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Iodobenzylguanidine↗