Effect of roxithromycin on T lymphocyte proliferation and cytokine production elicited by mite antigen

Pathogen- and host-directed anti-inflammatory activities of macrolide antibiotics

Macrolide antibiotics possess several, beneficial, secondary properties which complement their primary antimicrobial activity. In addition to high levels of tissue penetration, which may counteract seemingly macrolide-resistant bacterial pathogens, these agents also possess anti-inflammatory properties, unrelated to their primary antimicrobial activity. Macrolides target cells of both the innate and adaptive immune systems, as well as structural cells, and are beneficial in controlling harmful inflammatory responses during acute and chronic bacterial infection. These secondary anti-inflammatory activities of macrolides appear to be particularly effective in attenuating neutrophil-mediated inflammation. This, in turn, may contribute to the usefulness of these agents in the treatment of acute and chronic inflammatory disorders of both microbial and nonmicrobial origin, predominantly of the airways. This paper is focused on the various mechanisms of macrolide-mediated anti-inflammatory activity which target both microbial pathogens and the cells of the innate and adaptive immune systems, with emphasis on their clinical relevance.

Infections and asthma

A new paradigm is developing in regard to the interaction between infection and asthma. This paradigm comprises the acute exacerbations seen in asthma and also asthma chronicity. Viral infections have been commonly evaluated in acute exacerbations, but findings suggest viral-allergen and viral-bacterial interactions are important for chronicity. Most recently, studies are also invoking atypical bacterial infections, Mycoplasma pneumoniae and Chlamydia pneumoniae, as factors in both acute exacerbation and chronic asthma.

Mechanism of Thymus- and Activation-Regulated Chemokine (TARC)/CCL17 Production and its Modulation by Roxithromycin

Stimulation with tumor necrosis factor (TNF)alpha and interferon (IFN)gamma synergistically induced thymus- and activation-regulated chemokine (TARC)/CCL17 production from HaCaT keratinocytes (KC). Inhibitors for nuclear factor kappa B (NFkappaB), parthenolide, and Bay 11-7085, and an inhibitor of p38, SB202190, inhibited TNFalpha- and IFNgamma-induced production of CCL17 by HaCaT KC. Surprisingly, an inhibitor of epidermal growth factor receptor tyrosine kinase, PD153035, enhanced the production of CCL17 in HaCaT KC. Roxithromycin (RXM), a 14-membered ring macrolide, suppressed CCL17 production by HaCaT KC induced by IFNgamma and TNFalpha. RXM partially suppressed p38 phosphorylation and NFkappaB-driven luciferase activity induced by TNFalpha and IFNgamma. Degradation of inhibitor of nuclear factor kappa B (IkappaB) alpha upon stimulation with IFNgamma and TNFalpha was not affected by the addition of RXM. Through elucidating the mechanism of CCL17 production, our study indicates that RXM suppresses the production through the inhibition of p38 and NFkappaB, independent of the inhibition of IkappaB degradation.

Spray-dried plasma improves growth performance and reduces inflammatory status of weaned pigs challenged with enterotoxigenic Escherichia coli K88

We investigated whether spray-dried plasma (SDP) improved growth and health of piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). Forty-eight pigs weaned at 21 d (BW = 4.88 +/- 0.43 kg) received one of four diets containing 6% SDP or fish proteins (as-fed basis) either nonmedicated (SDP-NM and FP-NM diets) or medicated with 0 or 250 mg/kg of colistine + 500 mg/kg of amoxycycline (SDP-M and FP-M diets), for 15 d. On d 4, pigs were orally challenged with ETEC. On d 15, eight pigs per dietary group were killed, blood and saliva were collected for analysis of K88 fimbriae-specific immunoglobulin (Ig)-A, and jejunum was removed for villi preparation, histological analysis, and cytokine expression. The presence or absence of K88 receptors (K88+ and K88- pigs respectively) was determined by villous adhesion assay. Effects of protein source on ADG (P = 0.04) and ADFI (P < 0.01), as well of medication on ADFI (P < 0.02), of all pigs were observed. In sacrified pigs, there was an effect of protein source on ADG (P = 0.03) and ADFI (P < 0.001), as well an interaction between medication and presence of K88 receptor (P = 0.02) for feed:gain ratio. Plasma K88 specific IgA were low in all K88 pigs and higher in K88+ pigs fed FP-NM compared with all the other groups (P < 0.05), except SDP-M. An interaction was found among protein source, medication, and presence of K88 receptors (P = 0.04). Saliva IgA concentrations were high in all pigs fed FP-NM and low in all other pigs. Jejunum of pigs fed FP-NM showed some ulcerations, edema, and mild inflammatory cell infiltration (ICI). In pigs fed FP-M, edema was reduced. Conversely, only a mild ICI was observed in pigs fed SDP-NM and SDP-M. Crypt depth was increased in K88+ pigs fed SDP-NM and an interaction between protein source and presence of K88 receptors was observed (P < 0.05). Expressions of tumor necrosis factor-alpha and interleukin (IL)-8 were lower in pigs fed SDP-NM and SDP-M than in those fed FP-NM and FP-M, either K88- or K88+ (P < 0.01). In pigs fed FP diets, expression of IL-8 tended to increase (P = 0.08) in K88+ compared with K88- subjects. Expression of interferon-gamma increased in K88 and K88+ pigs fed FP-M as compared with other pigs (P < 0.01). These results indicate that feeding with SDP improved growth performance and protected against E. coli-induced inflammatory status, and suggest that use of SDP-NM can be considered a valid antibiotic alternative.

Antibiotics in asthma

Asthma pathogenesis appears to be a result of a complex mixture of genetic and environmental influences. There is evidence that Mycoplasma pneumoniae and Chlamydia pneumoniae play a role in promoting airway inflammation that could contribute to the onset and clinical course of asthma. If antimicrobial therapy can eradicate these organisms, it might be possible to alter the course of the disease. Although antibiotics have no role in the routine management of acute exacerbations of asthma, certain macrolide antibiotics have been shown to have anti-inflammatory activity. Part of this effect is due to their known inhibition of steroid and theophylline metabolism, but through a myriad of mechanisms that are incompletely understood, macrolide antibiotics have additional broad anti-inflammatory properties that might prove useful in the management of asthma and other inflammatory diseases.

Macrolide antibiotics: current and future uses

After a long history of anti-infective therapeutic use, macrolide antibiotics have not yet given up all their secrets. Interest in their therapeutic potential in inflammatory diseases (possibly including non-infectious diseases) has generated abundant fundamental research and therapeutic trials worldwide. The main question regarding the future prospects of this class of drugs is whether some macrolides are beneficial in such settings because they modulate host inflammatory responses (and cellular targets) or rather because they eliminate a latent, unidentified pathogen which triggers chronic inflammation. However, no clearcut results have yet been obtained.

Macrolide and occult infection in asthma

PURPOSE OF REVIEW

A small percentage of asthma exacerbations are linked with infection by an atypical bacterium, such as Chlamydia pneumoniae or Mycoplasma pneumoniae. These bacteria also have been proposed to cause occult chronic lower airway inflammation and to initiate nonatopic asthma in adults. Consequently, the logical procedure would be to eliminate these pathogens as soon and as thoroughly as possible using antibiotics. Nonetheless, antibiotics are not recommended even for the treatment of acute asthma exacerbations except as needed for comorbid conditions. These discrepancies highlight the need to define the role, if any, of antimicrobials that are active against atypical pathogens, mainly macrolides, but also tetracyclines and fluoroquinolones, in the treatment of asthma.

RECENT FINDINGS

Macrolides are antibiotics with both antimicrobial and antiinflammatory activities. Some studies have documented that these agents could be useful in the treatment of occult infection in asthma because of their antimicrobial activity against atypical pathogens. They could also lead to reduction of the airways inflammation by decreasing the transcription of mRNA for a variety of cytokines and inhibiting interleukin-8 release by eosinophils, and therefore improvement of symptoms and pulmonary function. These effects are not caused by bronchodilation, elevation of serum theophylline level, or steroid-sparing mechanism.

SUMMARY

The available clinical evidence seems to support use of macrolides in the treatment of asthma because of their antimicrobial activity. However, studies that may confirm this hypothesis are scarce and with limited scientific value because of their open, uncontrolled design.

Roxithromycin decreases ultraviolet B irradiation-induced reactive oxygen intermediates production and apoptosis of keratinocytes

BACKGROUND

In addition to their antimicrobial action, roxithromycin (RXM), a new 14-membrane macrolide antibiotics, have immunomodulatory, anti-inflammatory and anti-oxidative activity. Ultraviolet B (UVB) irradiation induces reactive oxygen intermediates and apoptosis of keratinocytes.

OBJECTIVE

To examine the anti-apoptotic and anti-oxidative effect of RXM on UVB-irradiated keratinocytes.

METHODS

UVB-induced apoptosis was determined by cell death assay using crystal violet staining, and DNA fragmentation assay. Superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and calatase activities were measured in UVB-irradiated SV40-trasnformed human keratinocytes (SVHK cells). Detection of superoxide was performed histologically using hydroethidine and colorimetric quantitative assay using ferrous irons. H(2)O(2) was measured by colorimetrical assay.

RESULTS

RXM suppressed UVB-induced apoptosis of SVHK cells. UVB-irradiated SVHK cells showed decreased SOD, GPx, GR, and catalase activities. RXM pretreatment suppressed the decrease in these enzyme activities with the maximal effect detected at 10microM of RXM. The effect was associated with suppression of UVB-induced superoxide and H(2)O(2) production.

CONCLUSION

The present study demonstrated that RXM has anti-apoptotic and anti-oxidative effects against UVB-irradiated keratinocytes.