Erythromycin-induced suppression of pulmonary antibacterial defenses. A potential mechanism of superinfection in the lung

Structural basis for motilin and erythromycin recognition by motilin receptor

Motilin is an endogenous peptide hormone almost exclusively expressed in the human gastrointestinal (GI) tract. It activates the motilin receptor (MTLR), a class A G protein-coupled receptor (GPCR), and stimulates GI motility. To our knowledge, MTLR is the first GPCR reported to be activated by macrolide antibiotics, such as erythromycin. It has attracted extensive attention as a potential drug target for GI disorders. We report two structures of G_q-coupled human MTLR bound to motilin and erythromycin. Our structures reveal the recognition mechanism of both ligands and explain the specificity of motilin and ghrelin, a related gut peptide hormone, for their respective receptors. These structures also provide the basis for understanding the different recognition modes of erythromycin by MTLR and ribosome. These findings provide a framework for understanding the physiological regulation of MTLR and guiding drug design targeting MTLR for the treatment of GI motility disorders.

Different Responses to Clarithromycin in Patients with Cryptogenic Organizing Pneumonia

Cryptogenic organizing pneumonia (COP) is an idiopathic interstitial pneumonia characterized by a subacute course and favorable prognosis with corticosteroids. However, some patients show resistance to steroids. Macrolides have been used with success in those patients showing resistance to steroids. A few reports showed treatment failure with macrolides in patients with COP who were resistant to steroids. In this report, we described two cases of COP who showed different responses to clarithromycin. One recovered completely, but the other gradually showed lung fibrosis with clarithromycin.

Enrofloxacin and macrolides alone or in combination with rifampicin as antimicrobial treatment in a bovine model of acute Chlamydia psittaci infection

Chlamydia psittaci is a zoonotic bacterium with a wide host range that can cause respiratory disease in humans and cattle. In the present study, effects of treatment with macrolides and quinolones applied alone or in combination with rifampicin were tested in a previously established bovine model of respiratory C. psittaci infection. Fifty animals were inoculated intrabronchially at the age of 6-8 weeks. Seven served as untreated controls, the others were assigned to seven treatment groups: (i) rifampicin, (ii) enrofloxacin, (iii) enrofloxacin + rifampicin, (iv) azithromycin, (v) azithromycin + rifampicin, (vi) erythromycin, and (vii) erythromycin + rifampicin. Treatment started 30 hours after inoculation and continued until 14 days after inoculation (dpi), when all animals were necropsied. The infection was successful in all animals and sufficient antibiotic levels were detected in blood plasma and tissue of the treated animals. Reisolation of the pathogen was achieved more often from untreated animals than from other groups. Nevertheless, pathogen detection by PCR was possible to the same extent in all animals and there were no significant differences between treated and untreated animals in terms of local (i.e., cell count and differentiation of BALF-cells) and systemic inflammation (i.e. white blood cells and concentration of acute phase protein LBP), clinical signs, and pathological findings at necropsy. Regardless of the reduced reisolation rate in treated animals, the treatment of experimentally induced respiratory C. psittaci infection with enrofloxacin, azithromycin or erythromycin alone or in combination with rifampicin was without obvious benefit for the host, since no significant differences in clinical and pathological findings or inflammatory parameters were detected and all animals recovered clinically within two weeks.

Macrolide therapy in chronic inflammatory diseases

Macrolides are a group of antibiotics with a distinctive macrocyclic lactone ring combined with sugars (cladinose, desosamine). The action of macrolides is to block protein synthesis by binding to the subunit of 50S ribosome of bacteria. Prototype macrolide was erythromycin, which came into clinical practice in the 50s of the 20th century. Its antimicrobial spectrum covers the scope of the penicillins but is extended to the impact of atypical bacteria. In the 90s more drugs of this group were synthesized—they have less severe side effects than erythromycin, extended spectrum of Gram-negative bacteria. Macrolides are effective in treating mycobacterial infections especially in patients infected with HIV. It is now known that in addition to antibacterial abilities, macrolides have immunomodulatory effects—they inhibit the production of proinflammatory cytokines (TNF, IL1, 6, and 8) affect transcription factors (NF-κB) as well as costimulaton (CD 80) and adhesion molecules (ICAM). This review article focused not only on the their antimicrobial abilities but also on efficacy in the treatment of several inflammatory disorders independent of the infectious agent. Their wider use as immunomodulators requires further study, which can lead to an extension of indications for their administration.

Diffuse Panbronchiolitis

Diffuse panbronchiolitis (DPB) is characterized by chronic sinobronchial infection and diffuse bilateral micronodular pulmonary lesions consisting of inflammatory cells. Studies on disease etiology point to a genetic predisposition unique to Asians. Early therapy for DPB was largely symptomatic. The advent of macrolide antibiotics, including erythromycin, roxithromycin and clarithromycin, has strikingly changed disease prognosis. Low-dose, long-term macrolide therapy for DPB originated from detailed observations of response to therapy in a single patient. The bactericidal activity of macrolides, particularly erythromycin, is not a significant factor for their clinical efficacy in DPB. Firstly, irrespective of bacterial clearance, clinical improvement is observed in patients treated with erythromycin. Secondly, even in cases with bacterial superinfection with Pseudomonas aeruginosa resistant to macrolides, treatment has proved effective. Thirdly, the recommended dosage of macrolides produces peak levels in tissue that are below the minimum inhibitory concentrations for major pathogenic bacteria that colonize the airway. In the last two decades, the possible mechanism underlying the effectiveness of macrolide therapy has been extensively studied. The proposed mechanism of action includes inhibition of excessive mucus and water secretion from the airway epithelium, inhibition of neutrophil accumulation in the large airway, inhibition of lymphocyte and macrophage accumulation around the small airway, and modulation of bacterial virulence. The great success of macrolide therapy in diffuse panbronchiolitis may extend its application to the treatment of other chronic inflammatory disorders. If the anti-inflammatory activity of macrolides is independent of their bactericidal effect, new anti-inflammatory macrolides without antimicrobial activity should be developed to minimize emergence of macrolide-resistant micro-organisms.

State of progress in treating cystic fibrosis respiratory disease

Since the discovery of the gene associated with cystic fibrosis (CF), there has been tremendous progress in the care of patients with this disease. New therapies have entered the market and are part of the standard treatment of patients with CF, and have been associated with marked improvement in survival. Now there are even more promising therapies directed at different components of the pathophysiology of this disease. In this review, our current knowledge of the pathophysiology of lung disease in patients with CF is described, along with the current treatment of CF lung disease, and the therapies in development that offer great promise to our patients.

Diffuse panbronchiolitis in East Asia

Diffuse panbronchiolitis is characterized by chronic sinobronchial infection and diffuse bilateral centrilobular lesions consisting of peribronchial infiltration of inflammatory cells. At present, it is known that diffuse panbronchiolitis is relatively restricted to East Asia. This uneven distribution is suspected to be highly associated with genetic predisposition located between human leucocyte antigen-A and -B loci. Low-dose, long-term macrolide therapy for the disease was suggested from a detailed observation of a single case that significantly improved by erythromycin therapy. Otherwise simple bactericidal activity of macrolides has been assumed as a candidate because of their clinical effect on the pathogenesis. In the last 10 years, the possible mechanism underlying the effectiveness of macrolide therapy has been dynamically investigated. To understand the pathological features and potential targets for macrolides in diffuse panbronchiolitis, the authors introduce the incidence of diffuse panbronchiolitis in East Asia, the profile of the disease and then trace the history of macrolide therapy in this review. The proposed mechanism of action includes the inhibition of excessive mucus and water secretion from the airway, the inhibition of neutrophil, and sometimes of lymphocyte and macrophage accumulating in the airway, the inhibition of transcription factors expressing several cytokines and the attenuation of bacterial virulence. Intracellular mechanisms of the action of macrolide are a hot topic of interest in research. The anti-inflammatory activity of macrolides is independent of their bactericidal effect, and a new anti-inflammatory analogue without antimicrobial activity should be developed to minimize the emergence of macrolide-resistant microorganisms and to maintain the safety of this treatment.

Anti-inflammatory and immunomodulating effects of clarithromycin in patients with cystic fibrosis lung disease

BACKGROUND AND AIM: Macrolide antibiotics are widely used in the treatment of suppurative lung diseases including cystic fibrosis (CF), the most common inherited fatal disease in the Caucasian population. This condition is characterized by secondary Pseudomonas infection resulting in neutrophil infiltration within the airways. The aim of the study was to investigate the evolution of inflammatory process in CF patients receiving long-term clarithromycin therapy. METHODS: Twenty-seven CF patients (mean age, 12 years) were enrolled into the study. Beside the basic therapy the patients were treated with clarithromycin at a dose of 250 mg every other day orally. All patients were routinely examined every 3 months. Blood and sputum were collected before clarithromycin treatment and then again 3, 6 and 12 months after the drug prescription. Cytokine concentrations (tumor necrosis factor-alpha, interleukin-8, interleukin-4, interferon-gamma) in the sputum and plasma were assayed. Peripheral blood lymphocyte response to phytohemagglutinin was also evaluated. RESULTS: Clarithromycin treatment resulted in a marked reduction of the cytokine levels both in the sputum and plasma specimens. At the same time, the interferon-gamma/interleukin-4 ratio has been significantly elevated. In addition, a sustained increase of peripheral blood lymphocyte response to phytohemagglutinin was demonstrated. These changes were associated with a significant improvement of the lung function. CONCLUSIONS: The beneficial effect of the prolonged treatment of CF patients with a 14-membered ring macrolide antibiotic clarithromycin seems to be associated not only with down-regulation of the inflammatory response, but also with immunological changes including the switch from Th2 to Th1 type response.

Azithromycin Blocks Neutrophil Recruitment inPseudomonasEndobronchial Infection

Macrolides exert their effects on the host by modulation of immune responses. In this study, we assessed the therapeutic efficacy of azithromycin in a murine model of mucoid Pseudomonas aeruginosa endobronchial infection. The clearance of Pseudomonas from the airway of mice treated with the macrolide azithromycin was not different than untreated mice challenged with Pseudomonas beads. However, the azithromycin-treated mice showed a remarkable reduction in lung cellular infiltrate in response to Pseudomonas beads, as compared with untreated mice. This effect was associated with significant decreases in lung levels of tumor necrosis factor-alpha and keratinocyte-derived chemokine in azithromycin-treated mice compared with untreated mice. Furthermore, there was a significant reduction in the response of both mouse and human neutrophils to chemokine-dependent and -independent chemoattractants when studied in vitro. Inhibition of chemotaxis correlated with azithromycin-mediated inhibition of extracellular signal-regulated kinase-1 and -2 activation. This study indicates that the azithromycin treatment in vivo results in significant reduction in airway-specific inflammation, which occurs in part by inhibition of neutrophil recruitment to the lung through reduction in proinflammatory cytokine expression and inhibition of neutrophil migration via the extracellular signal-regulated kinase-1 and -2 signal transduction pathway.

The effects of macrolides on inflammatory cells

Bronchial epithelial damage and mucus hypersecretion are characteristic features of chronic airway inflammation that can impair mucociliary clearance and can cause recurrent or persistent respiratory infection. In response to chemoattractants produced by damaged or inflamed tissue, neutrophils move through sequential steps of recruitment, migration, accumulation, and adhesion to endothelial and bronchial epithelial cells. Neutrophils engage in bacteriocidal activity by phagocytosis, release of lysosomal enzymes, and generation of reactive oxygen species, and they synthesize and release proinflammatory cytokines. Data confirm that many macrolide antibiotics have nonbactericidal properties that include inhibiting inflammatory cell chemotaxis, cytokine synthesis, adhesion molecule expression, and reactive oxygen species production. Macrolides also can decrease airway mucus hypersecretion in patients with diffuse panbronchiolitis, chronic sinusitis, and chronic bronchitis. Macrolides accumulate in neutrophils and macrophages at significantly higher concentrations than in extracellular fluid. This article discusses the action of macrolides on neutrophil accumulation, immune complex-mediated production of nitric oxide, mucin production, and the expanded therapeutic role of macrolides as biological response modifiers.

Diffuse panbronchiolitis: an underdiagnosed disease? Study of 4 cases in Brazil

BACKGROUND: Diffuse panbronchiolitis is a clinical pathologic condition characterized by chronic inflammation of respiratory bronchioles, with clinical features that position it as a differential diagnosis among the sinopulmonary syndromes. METHODS AND RESULTS: We present 4 cases (1 Black, 2 Japanese descendants, and 1 Japanese), living in Brazil, in which the diagnosis was made by the clinical and radiological features and confirmed by transbronchial biopsy. The clinical findings included chronic sinusitis, productive cough, rhonchi, and wheezes. The pulmonary function tests showed an obstructive pattern. High resolution computerized tomography showed a diffuse nodular pattern, airway ectasia, and airway wall thickening. The biopsy showed interstitial accumulation of foam cells and lymphoid cells in the walls of respiratory bronchioles: 2 of our cases had bronchus-associated lymphoid tissue hyperplasia. We searched for the HLA Bw54 in all of our patients, but only 1 was positive. A low dose macrolide treatment was introduced, resulting in with clinical and functional improvement. A score that rated the extent of nodules, airway ectasia, mucus plugging, and airway wall thickening was applied on pre- and post-treatment High resolution computerized tomography results, revealing an improvement in tomographic pattern related to that observed in the pulmonary function tests. CONCLUSION: We conclude that diffuse panbronchiolitis is a systemic disease that is not exclusive to the Asian population, whose clinical and radiological features should be better known by occidental pulmonary physicians.

Effect of telithromycin (HMR 3647) on polymorphonuclear neutrophil killing of Staphylococcus aureus in comparison with roxithromycin

HMR 3647 (telithromycin), a new ketolide, is active on intracellular pathogens. It was previously demonstrated that it inhibits superoxide anion production in a time- and concentration-dependent manner, at concentrations which inhibit 50% of the control response of about 55 microg/ml (5 min) to 30 microg/ml (30 min); these values are similar to those obtained with roxithromycin, a classical erythromycin A derivative. Here we investigated whether these drugs modified the bactericidal activity of human polymorphonuclear neutrophils (PMN) on four strains of Staphylococcus aureus with different profiles of susceptibility to macrolides and ketolides. We found that the main factor involved in killing was the antibacterial potency of the drugs, although combinations of antibiotics with PMN were slightly more active than each component used alone against two of the four strains. In addition, high concentrations of the drugs, which impaired the PMN oxidative burst, did not impair PMN bactericidal activity. Likewise, some cytokines which enhance PMN oxidative metabolism did not modify PMN bactericidal activity in the presence or absence of macrolides or ketolides. These data suggest that oxygen-independent mechanisms contribute to the bactericidal activity of PMN on these strains of S. aureus. Both live and/or heat-killed bacteria impaired the uptake of telithromycin and roxithromycin (but not that of levofloxacin, a quinolone) in a concentration-dependent manner, owing to a modulation of PMN transductional systems involved in the activation of the macrolide carrier.

Anti-inflammatory effects of macrolide antibiotics

Macrolides are widely used as antibacterial drugs. Clinical and experimental data, however, indicate that they also modulate inflammatory responses, both contributing to the treatment of infective diseases and opening new opportunities for the therapy of other inflammatory conditions. Considerable evidence, mainly from in vitro studies, suggests that leukocytes and neutrophils in particular, are important targets for modulatory effects of macrolides on host defense responses. This underlies the use of the 14-membered macrolide erythromycin for the therapy of diffuse panbronchiolitis. A variety of other inflammatory mediators and processes are also modulated by macrolides, suggesting that the therapeutic indications for these drugs may be extended significantly in future.

Risk of adverse effects in pneumonic foals treated with erythromycin versus other antibiotics: 143 cases (1986-1996)

OBJECTIVE

To determine whether foals with pneumonia that were treated with erythromycin, alone or in combination with rifampin or gentamicin, had a higher risk of developing adverse effects, compared with foals treated with trimethoprim-sulfamethoxazole (TMS), penicillin G procaine (PGP), or a combination of TMS and PGP (control foals).

DESIGN

Retrospective study.

ANIMALS

143 foals < 240 days old.

PROCEDURE

Information on age, sex, breed, primary drug treatment, total days of treatment with the primary drug, and whether the foal developed diarrhea, hyperthermia, or respiratory distress was obtained from the medical records. Relative risk (RR) and attributable risk (AR) were calculated to compare risk of adverse reactions between foals treated with erythromycin and control foals.

RESULTS

Only 3 (4.3%) control foals developed diarrhea; none developed hyperthermia or respiratory distress. Foals treated with erythromycin had an 8-fold risk (RR, 8.3) of developing diarrhea, compared with control foals, and increased risks of hyperthermia (AR, 25%) and respiratory distress (AR, 15%).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that use of erythromycin to treat foals with pneumonia was associated with an increased risk of diarrhea, hyperthermia, and respiratory distress, compared with use of TMS or PGP.

[Macrolides and Pseudomonas aeruginosa infection]

Several unique effects of subinhibitory concentrations of C14 and C15 macrolides on Pseudomonas aeruginosa infection are described in vitro: P. aeruginosa virulence factors inhibition, bacterial biofilm disruption, P. glycoprotein expression upregulation, anti-inflammatory and immunoregulatory effects. Clinical trials in vivo are warranted to assess the potential usefulness of macrolides for treatment of chronic infections caused by P. aeruginosa.

Interleukin-8 gene repression by clarithromycin is mediated by the activator protein-1 binding site in human bronchial epithelial cells

Macrolide antibiotics are known to be effective for the treatment of chronic inflammatory airway diseases including diffuse panbronchiolitis, chronic bronchitis, and bronchial asthma. Other than having antimicrobial activities, macrolides have antiinflammatory effects, such as the inhibition of cytokine production. In the present study we investigated the effects of clarithromycin (CAM) on interleukin (IL)-8 gene expression and protein levels, using the human bronchial epithelial cell line BET-1A. Northern blot analyses showed that CAM inhibited tumor necrosis factor (TNF)-alpha-induced IL-8 gene expression in a dose- and incubation time-dependent manner. The half-life of IL-8 messenger RNA transcripts in TNF-alpha-treated BET-1A cells did not change with CAM. Transfection studies with BET-1A cells, using fusion genes composed of the 5'-flanking sequences of the IL-8 gene and a luciferase reporter gene, demonstrated potent promoter activity in a 174-bp segment (-130 to +44 bp relative to the transcription start site). This segment includes activator protein (AP)-1 and nuclear factor (NF)-kappaB-like sites, and exhibited its strongest response to TNF-alpha. TNF-alpha-induced promoter activity in this segment showed a significant repression by CAM. However, a 156-bp segment (-112 to +44 bp) that does not include an AP-1 site but includes an NF-kappaB-like site did not show a significant repression of TNF-alpha-induced promoter activity by CAM. Mutation of the AP-1 binding site abrogated the suppression by CAM of TNF-alpha-induced enhancement of luciferase activity. In accord with promoter analyses, an electrophoretic mobility shift assay showed that CAM repressed AP-1 binding in TNF-alpha-treated BET-1A cells; however, TNF-alpha induced both AP-1 and NF-kappaB binding activities in BET-1A cells. These data suggest that macrolides such as CAM repress IL-8 gene transcription mainly via the AP-1 binding site in human bronchial epithelial cells. Our findings provide a novel mechanism for the antiinflammatory function of macrolides, implicating a target for the development of new drugs for treating chronic airway inflammation.

Erythromycin inhibits transcriptional activation of NF-kappaB, but not NFAT, through calcineurin-independent signaling in T cells

The molecular mechanism of the anti-inflammatory effect of erythromycin (EM) was investigated at the level of transcriptional regulation of cytokine gene expression in T cells. EM (>10(-6) M) significantly inhibited interleukin-8 (IL-8) expression but not IL-2 expression from T cells induced with 20 ng of phorbol 12-myristate 13-acetate (PMA) per ml plus 2 microM calcium ionophore (P-I). In electrophoretic mobility shift assays EM at 10(-7) to 10(-5) M concentrations inhibited nuclear factor kappa B (NF-kappaB) DNA-binding activities induced by P-I. Reporter gene assays also showed that EM (10(-5) M) inhibited IL-8 NF-kappaB transcription by 37%. The inhibitory effects of EM on transcriptional activation of IL-2 and DNA-binding activity of nuclear factor of activated T cells (NFAT) were not seen in T cells. On the other hand, FK506, which is also a macrolide derivative, inhibited transcriptional activation of both NF-kappaB and NFAT more strongly than EM did. The mechanism of EM inhibition of transactivation of NF-kappaB was further investigated in transiently transfected T cells that express calcineurin A and B subunits. Expression of calcineurin did not render transactivation of NF-kappaB in T cells more resistant to EM, while the inhibitory effect of FK506 on transactivation of NF-kappaB was attenuated. These findings indicate that EM is capable of inhibiting expression of the IL-8 gene in T cells through transcriptional inhibition and that this inhibition is mediated through a non-calcineurin-dependent signaling event in T lymphocytes.

Tc-99m erythromycin lactobionate inhalation scintigraphy in parenchymal lung diseases

We have investigated Technetium 99m erythromycin lactobionate (Tc 99m EL) clearance from the lungs after inhalation, in the presence of an alveolitis. Eighteen patients (6 sarcoidosis, 7 idiopathic fibrosis, and 5 miliary tuberculosis) were imaged after the patients inhaled 1,110 MBq of Tc 99m EL. Clearance half time for the first 45 min, for 24 h, and retention at 24 h correlated with percentage of lymphocytes in bronchoalveolar lavage fluid (BAL) (r = .729, r = .883, and r = .826, respectively). There was a positive correlation between peripheral penetration (PP) and forced expiratory volume in 1 s (FEV1) (r = .806) and forced vital capacity (FVC) (r = .781). Retention was more marked in sarcoidosis compared with tuberculosis (0.025 < p < or = 0.05). Radioaerosol lung imaging may reflect the pulmonary function impairment in parenchymal lung diseases. Retention of Tc 99m EL may be related to number of BAL cells or presence of a lymphocytic alveolitis. Long residency time of Tc 99m EL in the lungs implies that erythromycin can also be administered by inhalation for therapeutic purposes.

A macrolide antibiotic, roxithromycin, inhibits the growth of nasal polyp fibroblasts

Recently, the efficacy of macrolide antibiotics in cystic fibrosis and bleomycin-induced lung injury was reported. Nasal polyposis is a chronic inflammatory disease of the upper airway characterized by structural abnormalities including stromal fibrosis. Fibroblasts are resident cells thought to play an important role in the development of fibrosis. Although the effect of Roxithromycin (RXM) on inflammatory cells is well known, there is no evidence on the effect of RXM on fibroblasts. The purpose of the present study was two-fold: to examine the effect of RXM on the growth of fibroblasts in vitro and to examine the effect of RXM on the proliferation of fibroblasts in vivo. Nasal polyp fibroblast lines were generated from untreated patients, and those who were treated with RXM (300 mg/day) for one month before biopsy. Nasal polyp fibroblast lines from untreated patients were cultured for 72 hours with or without RXM, and the direct effect of RXM on fibroblast growth in vitro was examined by cell counting and 3H thymidine uptake. Next, we examined the in vivo effect of RXM on nasal polyp fibroblasts (NPFs) by comparing the growth characteristics of NPF lines from RXM treated and untreated patients. Finally, we examined the proliferating rate of NPF lines from the same patient before and after treatment with RXM. NPF lines that were treated with RXM exhibited a lower proliferating rate in vitro as compared to those that were not treated with RXM. Treatment of NPF lines with RXM suppressed the proliferation of fibroblasts in a dose-dependent manner. In addition, NPF lines from patients treated with RXM exhibited a lower proliferating rate in vitro as compared to NPF lines from the same patient taken before RXM treatment. We demonstrated that RXM directly suppressed nasal polyp fibroblast proliferation, and that this effect of RXM on fibroblast growth was persistent, indicating that RXM may prevent the progression of nasal polyposis by inhibiting the development of fibrosis.

Effects of erythromycin on experimental extrinsic allergic alveolitis

BACKGROUND

Recent clinical studies have demonstrated the efficacy of erythromycin for treating patients with chronic lower respiratory tract inflammation. Mechanisms related to the anti-inflammatory action are yet to be determined.

OBJECTIVES

The therapeutic efficacy of erythromycin in experimental extrinsic allergic alveolitis (EAA) was evaluated.

METHODS

A murine model of EAA was developed by intratracheal inoculations with particulate Trichosporon mucoides followed by erythromycin or josamycin treatment. Cell populations, specific antibodies, chemotactic activities, TNF-alpha, IL-1beta, MIP-2 and KC of bronchoalveolar lavage fluid (BALF); histopathology of the lung and footpad reaction; myeloperoxidase of the whole lung; and immunohistochemistry of intercellular adhesion molecule- (ICAM-1), at 6 and 96 h after the challenge, were examined.

RESULTS

There was a marked neutrophilic alveolitis and bronchiolitis at 6 h, and lymphocytic alveolitis and perivenule cuffing at 96 h after the challenge. Increase in total inflammatory cells and neutrophils in BALF at 6h was significantly suppressed by pretreatment with 5 mg/kg/day of erythromycin intraperitoneally for 5 days (P<0.01), with no apparent effect on specific antibodies, chemotactic activity or cytokines. Erythromycin also suppressed the Arthus-type reaction in the footpad (P<0.01). Histopathological studies revealed that erythromycin markedly decreased neutrophils in the lung and skin lesions and myeloperoxidase in the lung, simultaneously with inhibiting ICAM-1 expression. The therapy has no remarkable effects on lymphocytes or 96 h response. Josamycin had no effects on the model.

CONCLUSIONS

The therapeutic dosage of erythromycin significantly suppressed acute neutrophil influx into the lung, intradermal Arthus reaction and the expression of ICAM-1 in the lesions of experimental EAA. Erythromycin may be effective for treating subjects with acute EAA.

Preventive effect of erythromycin on experimental bleomycin-induced acute lung injury in rats

BACKGROUND

Erythromycin has been reported to have an inhibitory effect on chronic inflammatory airway disease and chronic infiltration of neutrophils into the airway. Bleomycin (BLM) often induces interstitial lung fibrosis following acute lung injury. A study was undertaken to investigate the effects of erythromycin (EM) on experimental bleomycin-induced acute lung injury in rats.

METHODS

Bleomycin-induced lung injury was assessed by light microscopic examination, measurement of neutrophil elastase activity and of the interleukin 8 (IL-8) content in bronchoalveolar lavage (BAL) fluid. The potential inhibitory effect of erythromycin was assessed by overall comparison of erythromycin untreated (BLM alone), concurrently treated (BLM + EM), and pretreated (BLM + pre-EM) groups.

RESULTS

The neutrophil count and concentration of neutrophil-derived elastase in BAL fluid were significantly different in the three groups. The morphological changes of lung injury were also less extensive in rats pretreated with erythromycin. However, these protective effects were not marked in the group concurrently treated with erythromycin. Moreover, the concentration of IL-8 in the BAL fluid tended to be less in the erythromycin treated groups; however, there were no significant differences between the bleomycin-treated groups.

CONCLUSION

Erythromycin exhibits a prophylactic effect on acute lung injury induced by intratracheal administration of bleomycin, which is possibly associated with a downregulation of neutrophil-derived elastase.

Randomised trial of erythromycin on the development of chronic lung disease in preterm infants

AIMS

To determine if erythromycin given from birth reduces the inflammatory response and the incidence and severity of chronic lung disease.

METHODS

Seventy five infants less than 30 weeks of gestation and ventilated from birth for lung disease were randomly assigned to receive erythromycin intravenously for 7 days or to no treatment. Ureaplasma urealyticum was detected in tracheal secretions by culture and polymerase chain reaction. Differential cell counts were obtained from bronchoalveolar lavage fluid collected daily for 5 days and concentrations of the cytokines interleukins IL-1 beta and IL-8, and tumour necrosis factor alpha (TNF-alpha) were measured. Chronic lung disease (CLD) was defined as oxygen dependency at 36 weeks of gestation.

RESULTS

Nine infants (13%) were positive for U urealyticum. The inflammatory cytokines in the lungs increased over the first 5 days of life in all babies, but no association was found between their concentrations and the development of CLD. Those treated with erythromycin showed no significant differences from the non-treated group in the differential cell counts or concentrations of the cytokines. The two groups had a similar incidence of CLD. Babies infected with U urealyticum did not have a more pronounced cytokine response than those without infection. Chorioamnionitis was associated with significantly higher concentrations of IL-1 beta and IL-8 on admission: these babies had less severe acute lung disease and developed significantly less CLD.

CONCLUSIONS

U urealyticum in the trachea was not associated with an increased inflammatory response in preterm infants. Erythromycin did not reduce the incidence or severity of CLD.

Effects of erythromycin on chemoattractant-activated human polymorphonuclear leukocytes

1. Erythromycin (2-100 micrograms ml-1) produced a concentration-related inhibition of superoxide generation and elastase release induced by in vitro exposure of human polymorphonuclear leukocytes (PMNs) to the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (FMLP; 30 nM). 2. By contrast, erythromycin (100 micrograms ml-1) did not alter the leukotriene B4 production elicited by FMLP (30 nM; in the presence of thimerosal 20 microM) or the intracellular calcium changes promoted by FMLP (30 nM; in the absence or presence of thimerosal 20 microM). 3. These results indicate that by reducing chemoattractant-triggered release of oxidative and proteolytic mediators from human PMNs, erythromycin may have clinically useful antiinflammatory effects.

Erythromycin modulates IL-8 expression in normal and inflamed human bronchial epithelial cells

Erythromycin (EM) and its 14-member macrolide analogues have attracted attention for its effectiveness in a variety of airway diseases, including diffuse panbronchiolitis (DPB), sinobronchial syndrome, and chronic sinusitis. However, its mechanisms of action remain unelucidated. We evaluated the effects of several antibiotics on IL-8 expression by normal and transformed human bronchial epithelial cells, an important source of this potent chemokine involved in cell recruitment into the airways. EM and clarithromycin (CAM) uniquely suppressed mRNA levels as well as the release of IL-8 at the therapeutic and noncytotoxic concentrations (% inhibition of IL-8 protein release: 25.0 +/- 5.67% and 37.5 +/- 8.99%, respectively, at 10(-6) M). The other antimicrobes, including a 16-member macrolide josamycin, showed no effect. Bronchial epithelial cells from very peripheral airways as well as from main bronchi were obtained from patients with chronic airway inflammatory diseases, and EM and CAM inhibited IL-8 release from these cells. Among five patients who underwent bronchoscopy before and after macrolide treatment, four showed decreased levels of IL-8 expression in airway epithelium as assessed by reverse transcription and polymerase chain reaction. Our findings showed these 14-member macrolides had inhibitory effect on IL-8 expression in human bronchial epithelial cells, and this new mode of action may have relevance to their clinical effectiveness in airway diseases.

Effects of long-term low-dose macrolide administration on neutrophil recruitment and IL-8 in the nasal discharge of chronic sinusitis patients

Effects of long-term low-dose macrolide administration were studied in patients with chronic sinusitis. Twelve patients with non-allergic chronic sinusitis were orally given 150 mg roxithromycin once a day without other treatments. The patients underwent computed tomography before and after the treatment, and paranasal sinus aeration was analyzed quantitatively. The number of neutrophils in the nasal smear was semiquantitatively assessed on a grading scale, and the IL-8 concentration in the nasal discharge was measured by enzyme immunoassay. The aeration of all four sinuses significantly improved, and recruited neutrophils and the IL-8 level in the nasal discharge were simultaneously reduced after the treatment. These findings suggest that long-term low-dose roxithromycin administration inhibits the positive feedback mechanism of neutrophil recruitment and IL-8 production by the recruited neutrophils, which is considered to be an essential cause of the prolongation of sinusitis.

Roxithromycin attenuates acid-induced cough and water-induced bronchoconstriction in children with asthma

In the present study, we evaluated the effect of roxithromycin, a semisynthetic macrolide antibiotic, on the cough response to inhaled acetic acid (AA) and on the bronchoconstriction induced by ultrasonically nebulized distilled water (UNDW) in children with asthma. Ten hospitalized asthmatic children (8 boys and 2 girls, mean +/- SEM age 12.6 +/- 0.4 years) were enrolled in this study. They were treated with 150 mg of roxithromycin once a day orally for 8 weeks without any side effects. All the patients underwent AA inhalation challenge before and 2, 4, and 8 weeks after the administration of roxithromycin. Seven of the 10 patients, who had a fall in FEV1 of at least 20% after UNDW inhalation, underwent UNDW inhalation challege at the same time. The cough threshold values, the lowest concentrations of AA eliciting coughs, and UNDW provocative dose producing a 20% fall in FEV1 (UNDW PD20) values 4 or 8 weeks after the administration of roxithromycin increased significantly over the initial values (p < 0.05). No significant change was observed in baseline FEV1 or serum theophylline concentrations throughout the study. These results support the notion that administration of roxithromycin may have favorable results in the treatment of childhood asthma.

Mechanism of neutrophil recruitment induced by IL-8 in chronic sinusitis

BACKGROUND

The mechanism of neutrophil recruitment in patients with chronic sinusitis is unclear.

OBJECTIVE

This study aims to elucidate the role of IL-8 in inducing neutrophil accumulation in the nasal discharge of patients with chronic sinusitis.

METHODS

Nasal discharge and mucosal specimens were obtained from two groups of patients, those with chronic sinusitis and those with allergic rhinitis. The samples were subjected to immunohistochemical examination and in situ hybridization. The IL-8 level in the nasal discharge was measured by enzyme immunoassay.

RESULTS

Immunoreactivity to IL-8 was observed in polymorphonuclear cells of nasal smear, in nasal gland duct cells, and in epithelial cells of the chronic sinusitis group; whereas those of the allergic rhinitis group mostly showed little or no reaction. Similar patterns of localization were shown by in situ hybridization for IL-8 messenger RNA. The IL-8 level in nasal discharge was significantly higher in the chronic sinusitis group than in the allergic rhinitis group.

CONCLUSION

These results suggest that chemotactic factors in sinus effusion, including IL-8 derived from nasal gland duct cells and epithelial cells, attract neutrophils out of mucosa, and the neutrophils that have emigrated into the sinus effusion secrete IL-8. This induces further neutrophil accumulation in the sinus effusion of patients with chronic sinusitis.

Effects of roxithromycin and erythromycin on interleukin 8-induced neutrophil recruitment and goblet cell secretion in guinea pig tracheas

Inhaled interleukin 8 caused an increase in goblet cell secretion in guinea pig tracheas, which was accompanied by mucosal infiltration of neutrophils. These responses were inhibited by pretreatment with roxithromycin or erythromycin in a dose-dependent fashion. Macrolides may thus be a value in protecting against neutrophil-associated airway hypersecretion.

Immunomodulating effects of antibiotics: literature review

Antibiotics can interact directly with the immune system. This is a review of the immunomodulating effects of antibiotics. The Medline database on CD-ROM was searched for the years 1987 to 1994 using the following search string: "thesaurus explode antibiotics/all AND (thesaurus explode immune-system/drug effects OR thesaurus immune-tolerance/drug effects)." Aspects of the immune system studied were aspects of phagocyte functions: phagocytosis and killing, and chemotaxis and aspects of lymphocyte functions: lymphocyte proliferation, cytokine production, antibody production, delayed hypersensitivity and natural killer-cell activity. In order to quantify and to compare immunomodulatory properties of antibiotics we calculated an "immune index," defined as: number of positive statements--number of negative statements/total number of statements. Concerning phagocytosis, positive effects were observed for cefodizime, imipenem, cefoxitin, amphotericin B and clindamycin and negative effects for erythromycin, roxithromycin, cefotaxime, tetracycline, ampicillin and gentamicin. Clindamycin, cefoxition and imipenem induce enhancement of chemotaxis, whereas cefotazime, rifampicin and teicoplanin decrease chemotaxis. Regarding lymphocyte proliferation, cefodizime has the strongest stimulating effect, whereas tetracycline has the strongest negative effect. Except for erythromycin and amphotericin B the number of statements reported is too small to be conclusive for the interpretation of effects on cytokine production. Erythromycin and amphotericin B appear to stimulate cytokine production. As to antibody production, cefodizime has the strongest positive effect, whereas josamycin, rifampicin and tetracycline have marked negative effects. For delayed hypersensitivity and the natural killer-cell activity the number of statements is too small for any single antibiotic to be conclusive. There are three markedly immuno-enhancing antibiotics (imipenem, cefodizime and clindamycin) and eight markedly immuno-depressing antibiotics (erythromycin, roxithromycin, cefotaxime, tetracycline, rifampicin, gentamicin, teicoplanin and ampicillin).

Effect of macrolide antibiotics on macrophage functions

Macrolide antibiotics have a variety of actions other than antimicrobial activities. Recently, it has been suggested that macrolide antibiotics act as immunomodulators. In this study, we evaluated the effects of macrolide antibiotics on macrophage functions. For the macrophage, we used the mouse macrophage cell line J774.1. The following effects of macrolide antibiotics on macrophage functions were evaluated: the effect of macrolide antibiotics on macrophage growth; the phagocytosis of beads; cytocidal activity against Candida albicans; and chemotaxis to lipopolysaccharide (LPS). Macrolide antibiotics except for azithromycin significantly stimulated the growth of the macrophage. In addition, pretreatment with macrolide antibiotics except for roxithromycin significantly stimulated the macrophage phagocytosis of beads, macrophage chemotaxis to LPS, and macrophage cytocidal activity against Candida albicans. These results suggest that macrolide antibiotics stimulate macrophage functions.

Antibiotic effects on phagocyte chemiluminescence in vitro

Phagocytes are an essential defence against infection. Since drugs which affect their function may alter the outcome of infections, we have studied the effect of nine antibiotics on phagocyte function in vitro. The effects of antibiotics on the respiratory burst function of phagocytes from healthy adult donors were investigated using lucigenin-enhanced chemiluminescence in response to serum-opsonised zymosan. Aminoglycosides showed dose-dependent suppression of polymorphonuclear leucocyte chemiluminescence, except streptomycin which caused enhancement. Erythromycin caused profound suppression of chemiluminescence from both polymorphonuclear leucocytes and monocytes. Benzylpenicillin and the cephalosporins caused variable suppression of phagocyte chemiluminescence: cefotaxime increased monocyte chemiluminescence in some experiments. None of the drugs produced suppression at clinically relevant plasma concentrations, but erythromycin and some other drugs are preferentially concentrated in phagocytes to levels which suppress their oxidative metabolism in vitro. It is therefore possible that some antibiotics alter phagocyte function: ex vivo studies of phagocyte function in patients taking antibiotics would be valuable.

Effects of macrolide antibiotics on neurally mediated contraction of human isolated bronchus

BACKGROUND

Long-term administration of macrolide antibiotic substances is an alternative therapy used in the treatment of asthma and airway hyperresponsiveness, but neither its mechanism of action nor whether this substance exerts an immediate action in the airways is known.

METHODS

Contractile responses of human isolated bronchial strips to electrical field stimulation (EFS) and acetylcholine were assessed under isometric conditions in the absence and presence of erythromycin, roxithromycin, or clarithromycin.

RESULTS

Incubation of tissues with erythromycin (3 x 10(-5) mol/L) attenuated the contractile responses to EFS so that the stimulus frequency required to produce 50% of the maximal contraction increased from 4.1 +/- 0.5 to 10.1 +/- 0.7 Hz (mean +/- SE; p < 0.001). In contrast, contractile responses to acetylcholine were not changed. Erythromycin reduced the EFS-induced contraction in a concentration-dependent fashion; the maximal decrease from the baseline response was 92.8% +/- 3.6% (p < 0.001). This inhibitory effect was not altered by propranolol, indomethacin, ouabain, charybdotoxin, or mechanical removal of the epithelium. Roxithromycin and clarithromycin likewise inhibited neurally mediated contraction.

CONCLUSIONS

These results suggest that macrolides may inhibit cholinergic neuroeffector transmission in the human airway smooth muscle, probably by reducing exocytotic release of acetylcholine from the nerve terminals.

Erythromycin shortens neutrophil survival by accelerating apoptosis

Erythromycin is reported to have an anti-inflammatory action, which may account for its clinical effectiveness in the treatment of chronic inflammatory diseases such as diffuse panbronchiolitis. To evaluate the anti-inflammatory action of erythromycin, we examined the survival of isolated neutrophils with and without erythromycin. Erythromycin shortened neutrophil survival in a dose-dependent fashion, with a maximum effect at 10 micrograms/ml [corrected] and above. Survival at 24 h was 63.4% in medium with 10 micrograms of erythromycin per ml compared with 82.7% in control medium (P < 0.01). This shortening of survival was brought about by acceleration of apoptosis, as evidenced by transmission electron microscopy. In a manner similar to that of erythromycin, other macrolide antibiotics, i.e., clarithromycin, roxithromycin, and midecamycin, also shortened neutrophil survival, but neither the beta-lactams ampicillin and cefazolin nor the aminoglycoside gentamicin affected their survival. Erythromycin increased intracellular levels of cyclic AMP (cAMP) to 150% of control levels in neutrophils. Forskolin, rolipram, and dibutyryl-cAMP, which are known to increase intracellular cAMP levels, also shortened neutrophil survival. H-89, an inhibitor of cAMP-dependent protein kinase A, partially blocked the survival-shortening effect of erythromycin. Our findings suggest that erythromycin shortens neutrophil survival at least in part through elevation of intracellular cAMP levels.

Erythromycin inhibits neutrophil chemotaxis in bronchoalveoli of diffuse panbronchiolitis

The efficacy of low dose long-term erythromycin (EM) therapy in the treatment of chronic lower respiratory tract disease, including diffuse panbronchiolitis (DPB), has been reported, but its therapeutic mechanism is still unclear. In 13 patients receiving oral EM therapy the accumulation of neutrophils in bronchoalveolar lavage (BAL) fluid was significantly reduced (p < 0.05), this reduction corresponds with an improvement in clinical symptoms. We sought to determine whether neutrophil chemotactic activity (NCA) in lavage fluid obtained from these 13 patients with DPB would respond to EM therapy. Pretreatment NCA in all patients was significantly elevated compared with levels in normal healthy nonsmoking volunteers (p < 0.001), and the level was greatly reduced after EM therapy (p < 0.001). In addition, this reduction correlated with increased percentages of neutrophils in the BAL fluid (r = 0.737, p < 0.01). Gel-filtration chromatography was also performed to characterize chemotactic factors. Pre-EM treatment BAL fluid revealed four NCA peaks (about molecular weight 15,000, 8,000, 1,500, and 300 daltons) in the elution profile, and chemotactic activity was reduced in all areas after EM therapy. These findings indicate that NCA in lavage fluid from patients with DPB consists of various components. Although it was not clear which component is predominantly affected, these results indicate that EM may inhibit the migration of neutrophils to inflammatory sites by reducing the intrapulmonary chemotactic gradient, thus, ultimately reducing pulmonary inflammation.

Role of interleukin-8 (IL-8) and an inhibitory effect of erythromycin on IL-8 release in the airways of patients with chronic airway diseases

To evaluate of the role of interleukin-8 (IL-8), a chemotactic cytokine, in the continuous neutrophil accumulation in the airways of patients with chronic airway disease (CAD) and persistent Pseudomonas aeruginosa infection, we investigated the cell population, IL-8 levels, IL-1 beta levels, tumor necrosis factor (TNF) activities, and neutrophil elastase (NE) activities of bronchoalveolar lavage (BAL) fluids in 17 CAD patients (with P. aeruginosa infections [CAD+PA], n = 9; without any bacterial infections [CAD-PA], n = 8) and 8 normal volunteers. We found significant elevations of neutrophil numbers, IL-8/albumin ratios, and NE/albumin ratios in BAL fluids from CAD patients, in the following rank order: CAD+PA > CAD-PA > normal volunteers. IL-1 beta/albumin ratios were elevated only in CAD+PA, while no TNF bioactivity was detected in BAL fluids. The neutrophil numbers correlated significantly with the IL-8/albumin ratios and NE/albumin ratios in the BAL fluids of CAD patients. When anti-human IL-8 immunoglobulin G was used for neutralizing neutrophil chemotactic factor (NCF) activities in BAL fluids, the mean reduction rate of NCF activities in CAD+PA patients was significantly higher than that in CAD-PA patients. We also evaluated the effects of low-dose, long-term erythromycin therapy in BAL fluids from three CAD+PA and two CAD-PA patients. Treatment with erythromycin caused significant reductions of neutrophil numbers, IL-8/albumin ratios, and NE/albumin ratios in BAL fluids from these patients. To elucidate the mechanism of erythromycin therapy, we also examined whether erythromycin suppressed IL-8 production by human alveolar macrophages and neutrophils in vitro. We demonstrated a moderate inhibitory effect of erythromycin on IL-8 production in Pseudomonas-stimulated neutrophils but not in alveolar macrophages. Our data support the view that persistent P. aeruginosa infection enhances IL-8 production and IL-8-derived NCF activity, causing neutrophil accumulation in the airways and the progressive lung injuries observed in patients with CAD. The clinical efficacy of erythromycin therapy for CAD patients might be partly mediated through a reduced IL-8 production, diminishing neutrophil accumulation and NE release in the airways.

Roxithromycin reduces the degree of bronchial hyperresponsiveness in children with asthma

We evaluated the effects of a new semisynthetic macrolide antibiotic, roxithromycin, on the bronchial hyperresponsiveness to histamine in children with asthma. Twelve hospitalized asthmatic children, aged 11 to 15 years (mean age, 12.9 years), were enrolled in this study. They were treated with 150 mg of roxithromycin once a day orally for 8 weeks without any side effects. The PC20 value 4 or 8 weeks after the administration of roxithromycin increased significantly over the initial values (p < 0.05, p < 0.01, respectively). No significant change was observed in serum theophylline concentrations during this study. Serum cortisol level in the morning did not change after the administration of roxithromycin for 4 weeks. These results suggest that administration of roxithromycin may act favorably in the treatment of childhood asthma.

Macrolide antibiotics protect against endotoxin-induced vascular leakage and neutrophil accumulation in rat trachea

We studied the effects of macrolides on lipopolysaccharide (LPS)-induced airway inflammation in the rat tracheal mucosa. Erythromycin and roxithromycin dose dependently inhibited microvascular leakage and neutrophil recruitment induced by LPS. This inhibitory action on vascular permeability was abolished by neutrophil depletion.

Cimetidine does not impair pulmonary clearance of Pseudomonas aeruginosa in normal rats

Histamine (H2)-receptor blockers are commonly used in critically ill patients to prevent gastric bleeding and have been implicated in the pathogenesis of gram-negative bacterial (GNB) nosocomial pneumonia. These experiments were undertaken to determine if cimetidine affects pulmonary GNB clearance. Groups of normal Sprague-Dawley rats were given cimetidine (75 mg/kg) or an equal volume of sterile buffer intraperitoneally every 6 hr for 24 hr prior to intratracheal challenge with 1.0 x 10(8) Pseudomonas aeruginosa. At 6 and 24 hr after challenge, animals were sacrificed and gastric pH, quantitative lung cultures, and total and differential [alveolar macrophages (AM) and polymorphonuclear leukocytes (PMN)] cell counts in bronchoalveolar lavage fluid were performed. Results showed that cimetidine therapy resulting in gastric pH greater than 4.0 has no effect on the pulmonary clearance of P. aeruginosa.

Erythromycin does not directly affect neutrophil functions

To determine whether erythromycin could affect neutrophil functions, we measured N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced chemotaxis and superoxide generation of neutrophils in the presence of erythromycin at various concentrations. Erythromycin had no effect on either of them. We further confirmed that intracellular free calcium concentration ([Ca2+]i) was not influenced by FMLP stimulation in the presence of erythromycin. Our results indicate that erythromycin has no direct effects on neutrophil functions in vitro, although it is reported that erythromycin inhibits the local migration of neutrophils in the small airways of subjects with asthma.

Bronchointerstitial pneumonia and respiratory distress in young horses: clinical, clinicopathologic, radiographic, and pathological findings in 23 cases (1984-1989)

Twenty-three foals, between 1 and 7 months old, with signs of acute respiratory distress, were examined at the Veterinary Medical Teaching Hospital (VMTH), University of California, Davis, between 1984 and 1989. Characteristic features included sudden onset of severe respiratory distress and tachypnea, cyanosis unresponsive to nasal oxygen, pyrexia, hypoxemia, hypercapneic respiratory acidosis, poor response to treatment, and histopathologic lesions of bronchiolitis and bronchointerstitial pneumonia. Seven of the 23 foals were normal before the onset of respiratory distress, 3 foals were found dead, and 13 foals were being treated for respiratory tract infections at the time of presentation. Laboratory data obtained for 13 horses showed increased plasma fibrinogen concentration (630.7 +/- 193 mg/dL), leukocytosis (18,607 +/- 7,784/microL), and neutrophilia (13,737 +/- 8,211/microL). Thoracic radiographs showed a diffuse increase in interstitial and bronchointerstitial pulmonary opacity and, in 5 foals, an alveolar pulmonary pattern of increased density was also seen. In 3 foals heavy interstitial infiltration proceeded to a coalescing nodular radiographic appearance. Microbiological culture of tracheobronchial aspirates (TBA) from 9 foals yielded bacterial growth, but no one bacterial species was consistently isolated. Microbiological culture of postmortem specimens of the lung from 6 foals yielded growth of bacteria that included Escherichia coli, Enterobacter spp., Proteus mirabilis, Klebsiella pneumoniae, Rhodococcus equi, or beta-hemolytic Streptococcus spp. Tracheobronchial aspirates from 4 foals and lung samples collected from a further 4 foals at necropsy yielded no bacterial growth. Cultures were not taken from two foals premortem or postmortem. Virologic examination of TBA, lung tissue, or pooled organ tissue from 12 foals was negative. Viral culture of TBA from 1 foal showed cytopathic effects and positive immunofluorescence for equine herpes virus type II (EHV-II). In addition to the 3 foals that were found dead, 11 foals died or were euthanatized. Pathologic lesions were limited to the lungs in 50% of the foals; the remainder also had bowel lesions suggestive of hypoxic injury. The predominant histopathologic pulmonary lesions included bronchiolitis, bronchiolar and alveolar epithelial hyperplasia, and necrosis. Many bronchioles were filled with mucoid and fibrinocellular exudate. The peribronchiolar interstitium and adjacent alveolar spaces were also infiltrated with inflammatory cells and contained proteinaceous edema fluid. Type II cell hyperplasia and hyaline membrane formation were observed in the majority of foals and in 2 foals alveolar multinucleate giant cells were also present.(ABSTRACT TRUNCATED AT 400 WORDS)

Elevation of tumor-associated carbohydrate antigens in patients with diffuse panbronchiolitis

We investigated the serum levels of the tumor-associated carbohydrate antigens sialyl SSEA-1 (SLX) and sialyl Lewis(a) (CA19-9) in patients with diffuse panbronchiolitis (DPB) and other nonmalignant lung diseases. Both antigens were high in the serum and bronchoalveolar lavage fluid (BALF) of patients with DPB, bronchiectasis (BE), idiopathic pulmonary fibrosis (IPF), and interstitial pneumonia associated with collagen vascular disease (CVD). Markedly high levels of the antigens were demonstrated in the serum and BALF from patients with DPB. An immunohistochemical study of open-lung biopsy specimens from patients with DPB indicated that these antigens were selectively expressed on the bronchiolar epithelial cells and mucinous exudates in airspaces. Low-dose, long-term erythromycin (EM) treatment was recently reported to be effective for DPB, and we investigated its influence on serum and BALF antigen levels in DPB patients. Antigen levels in both serum and BALF decreased after EM treatment, with improvement of symptoms and laboratory data, and there was a significant correlation between the reduction in the SLX level in serum and neutrophil percentage in BALF pre- and post-EM treatment. Our result suggests that secreted carbohydrate antigens from the bronchiolar epithelium in DPB may appear in the serum as a result of airway damage in the lower respiratory tract, and serum levels of the antigens may be decreased by a reduction in neutrophils in BALF after EM treatment.

In vitro stimulation of polymorphonuclear cell adhesion by ribomunyl and antibiotic + ribomunyl combinations: effects on CD18, CD35 and CD16 expression

Several functions of polymorphonuclear cells (PMNs) require adhesion to occur. Various membrane proteins' functions such as CD18 (beta 2 chain of integrin), CD35 (CR1) and CD16 (F c gamma Receptor III) participate in adhesion. In vivo treatment with Ribomunyl (R), an immunomodulating agent, was shown to enhance adhesion and migration of PMNs. To explore the direct effect of R on PMNs, cells from healthy subjects were treated in vitro with R. A significant increase of PMN adhesion and expression of CD18 and CD35 molecules were observed with 50 and 100 micrograms/ml of R after 2 h incubation. However, R-treatment decreased the PMN reactivity towards anti-CD16 (F c gamma RIII) monoclonal antibody. The effect of R on adhesion and membrane molecule expression was independent of the presence of serum and of polymixin B. Thus, this effect cannot be due to lipopolysaccharide (LPS) contaminants and does not require interactions with serum components. In previous studies, it was shown that in vitro amoxicillin increased some PMN functions whereas josamycin decreased them. The in vitro incubation of PMNs with R and amoxicillin (100 micrograms/ml) potentiated the positive effect of amoxicillin on adhesion and the antibiotic counterbalanced the negative effect of R on CD16 expression. In addition, R compensated the negative effect of josamycin (100 micrograms/ml) on PMN adhesion and on CD18 and CD35 expression. This study indicates: (1) the direct effect of R on PMN adhesion and on expression of molecules involved in adhesive-mediated functions, and (2) the beneficial effect of the association of R with antibiotics which can stimulate PMN activity.

Anti-allergic activity of roxithromycin: inhibition of interleukin-5 production from mouse T lymphocytes

This study was designed to evaluate the effects of roxithromycin (RXM), a newly synthesized macrolide antibiotic on allergic responses in mice. RXM was orally administered into BALB/c mice once a day for 42 days in a single dose of 5 mg/kg body weight. Spleen cells (Sp C) collected from mice on day 7, 14, 28 and 42 post-RXM administration showed higher blastic activity of lymphocytes than those from control. The activity peaked on the 7th day, then gradually decreased, and returned to the control level by the 42nd day. Production of cytokines, IL-2 and IL-5, by Sp C in response to concanavalin A stimulation was also examined in the course of RXM administration. The capacity of Sp C to produce IL-2 was enhanced by oral administration of RXM for 28 days. However, a long-term (for 42 days) administration inhibited it. On the other hand, the capacity of of Sp C to produce IL-5 was strongly inhibited by oral administration of RXM; the titer of IL-5 was similar to that obtained in cultures of Sp C from control mice. These results strongly suggest that oral administration of RXM inhibits the function of Th2-type helper T lymphocytes and that a long-term administration of RXM may be beneficial in asthma and allergy.