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Biomedical subjects

M S Kavuru

Publications and source records attributed to M S Kavuru.

At least 19 recordsLinked to original sources
PubMed2001

Eosinophils are a major source of nitric oxide-derived oxidants in severe asthma: characterization of pathways available to eosinophils for generating reactive nitrogen species.

Eosinophil recruitment and enhanced production of NO are characteristic features of asthma. However, neither the ability of eosinophils to generate NO-derived oxidants nor their role in nitration of targets during asthma is established. Using gas chromatography-mass spectrometry we demonstrate a 10-fold increase in 3-nitrotyrosine (NO(2)Y) content, a global marker of protein modification by reactive nitrogen species, in proteins recovered from bronchoalveolar lavage of severe asthmatic patients (480 +/- 198 micromol/mol tyrosine; n = 11) compared with nonasthmatic subjects (52.5 +/- 40.7 micromol/mol tyrosine; n = 12). Parallel gas chromatography-mass spectrometry analyses of bronchoalveolar lavage proteins for 3-bromotyrosine (BrY) and 3-chlorotyrosine (ClY), selective markers of eosinophil peroxidase (EPO)- and myeloperoxidase-catalyzed oxidation, respectively, demonstrated a dramatic preferential formation of BrY in asthmatic (1093 +/- 457 micromol BrY/mol tyrosine; 161 +/- 88 micromol ClY/mol tyrosine; n = 11 each) compared with nonasthmatic subjects (13 +/- 14.5 micromol BrY/mol tyrosine; 65 +/- 69 micromol ClY/mol tyrosine; n = 12 each). Bronchial tissue from individuals who died of asthma demonstrated the most intense anti-NO(2)Y immunostaining in epitopes that colocalized with eosinophils. Although eosinophils from normal subjects failed to generate detectable levels of NO, NO(2-), NO(3-), or NO(2)Y, tyrosine nitration was promoted by eosinophils activated either in the presence of physiological levels of NO(2-) or an exogenous NO source. At low, but not high (e.g., >2 microM/min), rates of NO flux, EPO inhibitors and catalase markedly attenuated aromatic nitration. These results identify eosinophils as a major source of oxidants during asthma. They also demonstrate that eosinophils use distinct mechanisms for generating NO-derived oxidants and identify EPO as an enzymatic source of nitrating intermediates in eosinophils.

Eosinophil Peroxidase↗
PubMed2001

Human alveolar macrophages and monocytes as a source and target for nitric oxide.

Nitric oxide (NO) is synthesized in the lung and this free radical participates in a wide array of regulatory, protective, and adverse interactions with cells. Both excess NO and its insufficiency have been implicated in the pathogenesis of numerous lung diseases with inflammatory components. Much of the available data concerning the source and regulation of NO production is derived from rodent systems. However, the requirements for NO production are more stringent in human monocytes/macrophages than in rodent systems. In contrast to rodent macrophages, human moncytes/macrophages generally do not respond to cytokine triggers with NO production [J. Leukocyte Biol. 58 (1995) 643, J. Exp. Med. 181 (1995) 735] and if NO is detected the levels are generally low [J. Leukocyte Biol. 58 (1995) 643]. The regulation of macrophage NO in the human appears to be a more selective and variable process than that seen in the rodent macrophages. In the human lung, the function of NO as toxic pro-inflammatory or protective anti-inflammatory agent is unresolved. While not a major source of NO in the human lung, the alveolar macrophage is an important producer of cytokines and this production may be modified by NO. Clear evidence of abnormalities in NO levels in the lungs of patients with asthma, bronchiectasis, viral infections, lung cancer and primary pulmonary hypertension (PPH) has been documented. Elevated inflammatory cytokines and oxidant production have been associated with all of these disease states. In terms of cytokine production, NO has been shown to decrease nuclear factor kappa B (NF-kappaB) activation. However, oxidants may interact with NO to form toxic compounds (e.g., NO combines with superoxide anion to form peroxynitrite). Furthermore, such reactions may decrease the availability of NO for blocking inflammatory cytokine production. Thus, available data suggests that a multiplicity of factors affect NO regulatory properties in inflammatory situations.

Animals↗
PubMed2000

Pulmonary alveolar proteinosis is a disease of decreased availability of GM-CSF rather than an intrinsic cellular defect.

Granulocyte-macrophage colony stimulating factor (GM-CSF) deficient mice develop a pulmonary alveolar proteinosis (PAP) syndrome which is corrected by the administration/expression of GM-CSF. These observations implicate GM-CSF in the pathogenesis of human PAP. We hypothesized that human PAP may involve an intrinsic cellular defect in monocytes/macrophages with an inability to produce GM-CSF and/or respond to GM-CSF. Thus, we investigated the cytokine responses to GM-CSF and LPS from peripheral blood monocytes and alveolar macrophages from patients with idiopathic PAP and healthy controls. Macrophage inflammatory protein-1-alpha (MIP) was measured from GM-CSF-stimulated cells and GM-CSF was measured from LPS-stimulated cells by ELISA. The MIP and GM-CSF production by monocytes and alveolar macrophages did not differ between PAP patients and healthy controls. Growth of the GM-CSF-dependent human myeloid cell line TF-1 was inhibited by serum from all patients studied (n = 10) and all patients had anti-GM-CSF antibody in their serum. The BAL from PAP patients had less detectable GM-CSF by ELISA than healthy controls (P = 0.05); in contrast, the inhibitory cytokine, interleukin-10 (IL-10), was increased in PAP compared to controls (P = 0.04). IL-10 is a potent inhibitor of LPS-stimulated GM-CSF production from healthy control alveolar macrophages. These studies are the first to demonstrate that circulating monocytes and alveolar macrophages from PAP patients are able to synthesize GM-CSF and respond to GM-CSF, suggesting no intrinsic abnormalities in GM-CSF signaling. In addition, these observations suggest that PAP in a subset of patients is the result of decreased availability of GM-CSF due to GM-CSF blocking activity and reduced GM-CSF production by IL-10.

Adult↗
PubMed2000

Interleukin 10 (IL-10)-mediated inhibition of inflammatory cytokine production by human alveolar macrophages.

Alveolar macrophages are an important source of inflammatory cytokines in the lung. IL-10 has been shown to inhibit inflammatory cytokine production by human alveolar macrophages, but mechanisms are unclear. The purpose of the present study was to investigate whether IL-10 modified cytokine production by interference with transcriptional pathways. Alveolar macrophages were obtained from healthy controls by fiberoptic bronchoscopy and incubated with LPS+/-IL-10. Results indicated that steady state mRNA levels of tumour necrosis factor-alpha (TNF) and interleukin 1-beta (IL-1) decreased in the presence of IL-10. Consequently, electrophoretic mobility shift assays were performed using end-labelled nuclear factor-kappa B (NF-kappa B) or activator protein-1 (AP-1) probe. NF-kappa B binding was decreased in extracts from macrophages incubated for 4 h with LPS+IL-10 in comparison to those incubated with LPS alone. IL-10 also inhibited TNF secretion and NF-kappa B activation induced by another stimulus, staphylococcal toxin. Supershift assays revealed the presence of both p50 and p65 subunits of NF-kappa B. AP-1 was not affected by IL-10. Further examination of mechanisms indicated that IL-10 delayed the LPS-mediated degradation of the inhibitor protein I kappa B, thus delaying the nuclear translocation of the p65 subunit. These observations provide the first evidence that IL-10 antagonizes cytokine transcription in human alveolar macrophages by impeding the nuclear translocation of NF-kappa B by delaying the degradation of I kappa B.

Blotting, Western↗
PubMed2000

Exogenous granulocyte-macrophage colony-stimulating factor administration for pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by the accumulation of lipoproteinaceous material within the alveoli. Recent data suggest that granulocyte-macrophage colony- stimulating factor (GM-CSF) may be involved in the pathogenesis of PAP. To extend this understanding and clarify whether GM-CSF replacement confers benefit, we report the preliminary results for the first four patients in an open-label study of GM-CSF treatment for moderate exacerbation of PAP. All four patients had idiopathic PAP confirmed by open lung biopsy. Subcutaneous GM-CSF was self-administered once daily for 12 wk (dose escalation from 3 to 9 microg/kg/d). Response was assessed from symptom scores, arterial blood gas measurements, pulmonary function testing, and chest radiographs. Three of the four patients experienced symptomatic, physiologic, and radiographic improvement with GM-CSF. Responders experienced sufficient improvement in oxygenation as to eliminate the need for supplemental oxygen, and one patient was removed from the waiting list for lung transplantation. Improved oxygenation was not apparent until 8 to 12 wk after the start of therapy. Notably, expected increases in the peripheral white blood cell count did not occur, suggesting lack of a hematopoietic response to exogenous GM-CSF in PAP. We conclude that GM-CSF appears to benefit a subset of patients with adult PAP, and may represent an alternative to whole-lung lavage in treating the disease.

Adult↗
PubMed2000

Eosinophils generate brominating oxidants in allergen-induced asthma.

Eosinophils promote tissue injury and contribute to the pathogenesis of allergen-triggered diseases like asthma, but the chemical basis of damage to eosinophil targets is unknown. We now demonstrate that eosinophil activation in vivo results in oxidative damage of proteins through bromination of tyrosine residues, a heretofore unrecognized pathway for covalent modification of biologic targets in human tissues. Mass spectrometric studies demonstrated that 3-bromotyrosine serves as a specific "molecular fingerprint" for proteins modified through the eosinophil peroxidase-H(2)O(2) system in the presence of plasma levels of halides. We applied a localized allergen challenge to model the effects of eosinophils and brominating oxidants in human lung injury. Endobronchial biopsy specimens from allergen-challenged lung segments of asthmatic, but not healthy control, subjects demonstrated significant enrichments in eosinophils and eosinophil peroxidase. Baseline levels of 3-bromotyrosine in bronchoalveolar lavage (BAL) proteins from mildly allergic asthmatic individuals were modestly but not statistically significantly elevated over those in control subjects. After exposure to segmental allergen challenge, lung segments of asthmatics, but not healthy control subjects, exhibited a >10-fold increase in BAL 3-bromotyrosine content, but only two- to threefold increases in 3-chlorotyrosine, a specific oxidation product formed by neutrophil- and monocyte-derived myeloperoxidase. These results identify reactive brominating species produced by eosinophils as a distinct class of oxidants formed in vivo. They also reveal eosinophil peroxidase as a potential therapeutic target for allergen-triggered inflammatory tissue injury in humans.

Allergens↗
PubMed1999

Nitric oxide regulation of asthmatic airway inflammation with segmental allergen challenge.

BACKGROUND: Despite evidence of increased nitric oxide (NO) in asthmatic compared with healthy individuals, the role of NO in airway inflammation is unclear. OBJECTIVE: The purpose of the study was to determine the in vivo effects of localized allergen challenge on airway NO levels and transcription factor activation. METHODS: In this study localized allergen challenge was used as a model of asthmatic exacerbation to determine the relationship of NO to airway inflammation. RESULTS: With allergen challenge, asthmatic patients had a rise in airway NO levels, whereas NO levels in healthy controls did not change. The increased NO in asthma with allergen challenge compared with healthy control subjects was associated with an increase in inflammatory cytokines (GM-CSF and macrophage inflammatory protein-1) in epithelial lining fluid and eosinophilic infiltrate in bronchoalveolar lavage fluid (BAL) and biopsy specimens. To investigate the mechanisms of cytokine gene expression, activation of the transcription factors activator protein-1 and nuclear factor-kappaB (NF-kappaB) in cells from BAL were evaluated. Activator protein-1 was not activated before or after local allergen challenge. In contrast, NF-kappaB activation was less in BAL cells from asthmatic patients with increased NO in comparison with controls. CONCLUSION: Our studies are the first to suggest an inverse correlation between NF-kappaB and airway NO in a localized segmental allergen challenge model in allergic asthmatic patients. The current study demonstrates that activation of the inflammatory response (eg, cytokines, cellular infiltrate) in allergic asthmatic patients is temporally associated with increased airway NO. We propose that NO that is up-regulated by cytokines is part of an autoregulatory feedback loop (ie, allergen challenge stimulates inflammatory cytokine production, which in turn stimulates NO production, and NO down-regulates cytokine production).

Adult↗
PubMed1999

Role of bronchoscopy in asthma research.

Over the past 15 years, much has been learned about the presence of airway inflammation in asthma through the use of investigative bronchoscopy. It has become quite clear that inflammation is present even in mild asthma. In addition to the eosinophils, T-lymphocytes and a variety of cytokines have been identified to play a prominent role in asthmatic inflammation. The concept of delayed asthmatic response after allergen exposure and its relationship to cellular inflammation and airway hyper-reactivity has become more clearly established. Our understanding of asthmatic airway inflammation, however, is incomplete. As interesting as the database has been so far, investigative FB has not defined a unique profile for patients with asthma. Specifically, lavage or endobronchial biopsy has not identified parameters that help in the diagnosis, assessment of disease severity, prognosis, or likelihood to respond to specific therapies. Also, the exact relationship between parameters in lavage compared with mucosal biopsy and how these are related to airway hyper-reactivity and the clinical syndrome of asthma remains poorly understood. In this regard, it must be confessed that currently FB with lavage and biopsy in asthmatics needs to be considered as a research tool for specimen retrieval to help characterize and express inflammation. Although these techniques have contributed immensely to our understanding of asthma pathogenesis, presently these techniques do not have any practical role or clinical usefulness.

Asthma↗
PubMed1999

Differential regulation of human blood monocyte and alveolar macrophage inflammatory cytokine production by nitric oxide.

BACKGROUND: Nitric oxide (NO) has been associated with airway inflammation in asthma. Our previous work suggests that NO functions in an anti-inflammatory capacity through downregulation of stimulated cytokine secretion by normal human alveolar macrophages. Functional differences between alveolar macrophages and blood monocytes are thought to be related to maturation. OBJECTIVE: The purpose of this study was to determine the effect of NO on stimulated cytokine production by monocytes from asthmatics and normal healthy controls. METHODS: Monocytes and alveolar macrophages were obtained from normal volunteers (n = 13) and asthmatics with atopy (n = 7). Monocyte and alveolar macrophage cultures were stimulated with 0.5 microgram/mL lipopolysaccharide +/- 1.0 mM DETA NONOate (releases NO in culture with t1/2 = 20 hours at 37 degrees C) and incubated for 24 hours. Cell-free supernatants were collected and assayed by ELISA for tumor necrosis factor-alpha (TNF) and granulocyte macrophage colony stimulating factor (GM-CSF). RESULTS: Nitric oxide did not inhibit TNF production in monocytes of asthmatics and normals (mean +/- SEM % TNF stimulation = 19.6 +/- 9.7). Similar to previous results, NO did inhibit alveolar macrophages (% TNF suppression = 60.6 +/- 4.4). To determine whether this differential effect of NO on the two cell populations was related to maturation, monocytes were matured by culture for 7 days. The in vitro matured monocytes demonstrated 51.7 +/- 7.9% suppression of TNF. For each cell population, the responses of the asthmatics and healthy controls were not different. The differential effect is not cytokine specific since similar results were obtained with GM-CSF. CONCLUSION: These results demonstrate a differential effect of NO on monocyte and alveolar macrophages cytokine regulation and this effect may be related to the state of maturation.

Adolescent↗
PubMed1999

Uterine rhabdomyosarcoma metastatic to mediastinal lymph nodes: diagnosis by transbronchial needle aspiration.

Uterine rhabdomyosarcoma is rare, with only 60 reported cases. We describe an asymptomatic patient with metastatic uterine rhabdomyosarcoma manifested as extensive mediastinal lymphadenopathy. This 73-year-old woman had been previously treated for endometrial rhabdomyosarcoma and was referred to us when a right hilar density was seen on a chest radiograph; computed tomography showed a nodule in the right upper lobe and extensive right hilar and subcarinal lymphadenopathy. The diagnosis of metastatic rhabdomyosarcoma was made by fiberoptic bronchoscopy using transbronchial needle aspiration (TBNA). The patient is well 11 months after completing five cycles of chemotherapy. This is the first reported case of uterine rhabdomyosarcoma with metastasis to the mediastinum and the first case diagnosed with TBNA, which avoided the need for an invasive diagnostic procedure.

Aged↗
PubMed1999

A prospective evaluation of esophageal testing and a double-blind, randomized study of omeprazole in a diagnostic and therapeutic algorithm for chronic cough.

OBJECTIVE: Recent studies suggest an association between chronic cough and gastroesophageal reflux. Our study aims were 1) to define the prevalence of acid reflux induced cough in the general community, 2) to examine the ability of esophageal testing to identify gastroesophageal reflux related cough, and 3) to assess the utility of omeprazole in a chronic cough algorithm. METHODS: Patients with chronic cough of unknown etiology, who were mostly from the community, were evaluated. Subjects underwent a chest x-ray, methacholine challenge test, and empiric trial of postnasal drip therapy, and completed daily cough symptom diaries subjectively evaluating cough frequency and severity on a graded scale of 0-4 (combined maximum 8). After excluding other causes of cough, the remaining patients underwent esophageal and pH testing. Those testing positive were randomized to omeprazole 40 mg b.i.d. or placebo for 12 weeks. Follow-up was 1 yr. RESULTS: A total of 71 patients were screened; 48 were excluded. Twenty-three patients were evaluated for gastroesophageal reflux disease; six (26%) were eventually determined to have an acid-related cough. Of these patients, 17 had a positive pH test, six (35%) of whom showed a striking improvement or resolution of their cough during omeprazole treatment which was sustained for up to 1 yr. Six had a negative pH test, none of whom responded to omeprazole therapy. No significant differences were seen between responders (n = 6) and nonresponders (n = 11) for demographic factors, baseline symptom frequency and duration, or physiological parameters (motility/pH). CONCLUSIONS: Acid-related chronic cough was present in 26% (six of 23) of patients evaluated for gastroesophageal reflux disease. Esophageal testing does not reliably identify patients with acid induced chronic cough responsive to proton pump inhibitor therapy. We suggest that the best diagnostic and therapeutic approach, after excluding asthma and postnasal drip syndrome, is empiric treatment for 2 wk with a high dose proton pump inhibitor.

Adolescent↗
PubMed1999

Nitric oxide blocks nuclear factor-kappaB activation in alveolar macrophages.

Nitric oxide (NO) is an important endogenous regulatory molecule implicated in both proinflammatory and antiinflammatory processes in the lung. Previously, we demonstrated that in human alveolar macrophages (AM), NO decreased inflammatory cytokine production, including that of interleukin-1beta, tumor necrosis factor-alpha and macrophage inflammatory protein-1alpha. One mechanism by which NO could regulate such diverse cytokine production is through effects on the transcription factor nuclear factor-kappaB (NF-kappaB), which controls the expression of the genes for these inflammatory cytokines and growth factors. We therefore investigated whether NO affects NF-kappaB activation in AM in vitro and in vivo. In vitro studies with AM showed that NF-kappaB activation by lipopolysaccharide (LPS) is decreased by NO in a dose-dependent manner. NO prevented an LPS-mediated decrease in the NF-kappaB inhibitory protein IkappaB-alpha. In asthma, airway NO levels are increased, whereas in primary pulmonary hypertension (PPH), airway NO levels are lower than in healthy lungs. In vivo investigations were conducted with freshly isolated AM from healthy controls, asthmatic individuals, and PPH patients. Healthy individuals had airway NO levels of 8 +/- 2 ppb (mean +/- SEM), which is associated with low NF-kappaB activation. Asthma patients with airway NO levels > 17 ppb showed minimal NF-kappaB activation, whereas asthmatic individuals with NO levels </= 17 ppb showed greater NF-kappaB activation. PPH patients with low NO (1 +/- 1 ppb) had prominent NF-kappaB activation. These in vivo studies in asthma and PPH support the in vitro observation of an inverse relationship between NO and NF-kappaB activation. One mechanism by which NO blocks cytokine production involves IkappaB.

Asthma↗
PubMed1998

Pulmonary alveolar proteinosis: clinical features and outcomes.

INTRODUCTION: Pulmonary alveolar proteinosis (PAP) is a rare disease of unknown etiology and variable natural history. To date, the largest series from a single institution has consisted of 68 individuals. To extend the understanding of the clinical features and natural history of PAP, we present a series of 24 patients with PAP from a single institution. METHODS: Patients with PAP were identified by a review of The Cleveland Clinic Foundation discharge database from 1965 to 1995. After identification, a chart review of the 24 selected patients was conducted. Charts were abstracted for historical, diagnostic, and therapeutic features. Diagnosis was confirmed by a review of the lung biopsy, where it was available, by a lung pathologist. Follow-up by telephone was performed with 19 patients. RESULTS: Most patients (70%) were male, and smoking was common (75%; mean pack-years, 29) in the group. The mean age at initial evaluation was 43 years. Presenting symptoms were as follows: 19 patients (79%) reported dyspnea, 19 patients (79%) reported a cough, 4 patients (17%) reported hemoptysis, and 3 patients (13%) reported chest pain. The earliest available spirometry after presentation of symptoms showed a prediction of mean FEV1 of 74% (range, 45 to 99%) and a prediction of mean FVC of 76% (range, 41 to 99%). The diagnosis of PAP was established by transbronchial biopsy alone in 7 patients (29%) and by open-lung biopsy alone in 17 patients (71%). Whole lung lavage was deemed necessary in 13 patients (54%); 3 patients underwent lavage of one lung only, and 10 patients underwent bilateral whole lung lavage. Whole lung lavage was required only once in 46% of patients, and from two to four times in the remainder of patients. During the follow-up period (mean length of follow-up, 8.5 years; range, 5 months to 21 years), 25% of the patients died, but none as a result of sequelae of PAP. Half of the survivors reported persistent symptoms. CONCLUSIONS: In this series, which represents one of the largest single institutional experiences with PAP reported, the clinical features are largely consistent with previously reported cases. However, contrary to early reported experiences in which open-lung biopsy was frequently required to establish PAP and in which whole lung lavage was needed, transbronchial biopsy established the diagnosis in 29% of patients and whole lung lavage could be deferred in 46% of patients.

Adult↗
PubMed1997

Spontaneous resolution of rhodococcal pulmonary infection in a liver transplant recipient.

Pulmonary infection by Rhodococcus equi is characterized by indolent infection in an immunocompromised host with a propensity to form cavitary lesions. Mortality can be greater than 50%; treatment involves prolonged therapy with multiple antibiotics and, occasionally, surgical resection. Recurrence is common. We report a case of a liver transplant patient with a pulmonary nodule caused by R equi; the nodule followed a benign clinical course and resolved spontaneously. This case illustrates that the spectrum of disease caused by R equi is not fully appreciated and that significant pitfalls complicate the diagnosis and management of infection by this unusual and probably underrecognized pathogen.

Actinomycetales Infections↗