Doxycycline-a role in ocular surface repair

First aid for complications of infectious keratitis

Infectious keratitis is a fairly common entity in India. However while paying attention to the primary entity, the associated events may be overlooked. Enhanced pain usually suggests a worsening of the condition or development of associated problems like secondary glaucoma. However, contrary to logic, a sudden decrease in pain is also likely to suggest a worsening, e.g. perforation of the corneal ulcer. Various such problems with their management are outlined.

A novel formulation of inhaled doxycycline reduces allergen-induced inflammation, hyperresponsiveness and remodeling by matrix metalloproteinases and cytokines modulation in a mouse model of asthma

BACKGROUND

In this study, we assess the effectiveness of inhaled doxycycline, a tetracycline antibiotic displaying matrix metalloproteinases (MMP) inhibitory effects to prevent allergen-induced inflammation, hyperresponsiveness and remodeling. MMPs play key roles in the complex cascade of events leading to asthmatic phenotype.

METHODS

Doxycycline was administered by aerosols by the mean of a novel formulation as a complex with hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD) used as an excipient. BALB/c mice (n=16-24 in each group) were sensitized and exposed to aerosolized ovalbumin (OVA) from day 21 to 27 (short-term exposure protocol) or 5 days/odd weeks from day 22 to 96 (long-term exposure protocol).

RESULTS

In the short-term exposure model, inhaled doxycycline decreased allergen-induced eosinophilic inflammation in bronchoalveolar lavage (BAL) and in peribronchial areas, as well as airway hyperresponsiveness. In lung tissue, exposure to doxycycline via inhaled route induced a fourfold increase in IL-10 levels, a twofold decrease in IL-5, IL-13 levels and diminished MMP-related proteolysis and the proportion of activated MMP-9 as compared to placebo. In the long-term exposure model, inhaled doxycycline significantly decreased the extent of glandular hyperplasia, airway wall thickening, smooth muscle hyperplasia and subepithelial collagen deposition which are well recognized features of airway remodeling.

CONCLUSION

Doxycycline administered by aerosols decreases the allergen-induced airway inflammation and hyperresponsiveness and inhibits the development of bronchial remodeling in a mouse model of asthma by modulation of cytokines production and MMP activity.

Induction of inflammatory cytokines by a keratin mutation and their repression by a small molecule in a mouse model for EBS

Epidermolysis bullosa simplex (EBS) is a skin disorder caused by mutations in keratin (K) 5 or K14 genes. It is widely regarded as a mechanobullous disease, resulting from a weakened cytoskeleton, causing extensive cytolysis. It was postulated by others that certain K14 mutations induce tumor necrosis factor-alpha (TNF-alpha) and increase apoptosis. Here, we report that in K5-/- mice and in a cell culture model of EBS, the mRNA and protein levels of TNF-alpha remain unaltered. Transcriptome analysis of K5-/- mice revealed, however, that the proinflammatory cytokines IL-6 and IL-1beta were significantly upregulated at the mRNA level in K5-/- mouse skin. These results were confirmed by TaqMan real-time PCR and ELISA assays. We hypothesize that keratin mutations contribute to EBS in a mouse model by inducing local inflammation that mediates a stress response. Following clinical reports, we applied the small molecule doxycycline to K5-/- mice. We demonstrate that doxycycline extended the survival of neonatal K5-/- mice from less than 1 to up to 8 hours. Microarray and TaqMan real-time PCR showed a downregulation of matrix metalloproteinase 13 and IL-1beta, indicating an effect of doxycycline on transcription. Our data offer a novel small molecule-based therapy approach for EBS.

RETRACTED: Doxycycline alters the expression of matrix metalloproteases in the endometrial cells exposed to ovarian steroids and pro-inflammatory cytokine

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editors following an investigation by the Office of Research Integrity (ORI) at the Department of Health and Human Services. The investigation confirmed that the data presented has been falsified by the last author.

Doxycycline alters the expression of inflammatory and immune-related cytokines and chemokines in human endometrial cells: implication in irregular uterine bleeding*

BACKGROUND

Increased production of pro-inflammatory mediators is considered central in the manifestation of events leading to irregular uterine bleeding in progestin-only contraceptive users. Evidence suggests that in addition to its antimicrobial property, doxycycline (Dox) acts as an anti-inflammatory agent mainly through the suppression of pro-inflammatory mediators.

METHODS

We tested this hypothesis in the endometrial environment using an in vitro model consisting of isolated human endometrial glandular epithelial and stromal cells and a human endometrial surface (HES) epithelial cell line cultured under defined conditions.

RESULTS

We found that Dox at doses ranging from 1 to 100 microg/ml had a limited growth-inhibitory effect on these cells, whereas Dox in a dose-dependent manner inhibited the production of tumour necrosis factor-alpha (TNF-alpha). Using multiplex cytokine/chemokine protein analysis to test a broader range of Dox activity, we found that Dox at 25 microg/ml either alone or in the presence of 17beta-estradiol (E2), medroxyprogesterone acetate (MPA) and E2+MPA (10(-8) M) as well as TNF-alpha (25 ng/ml), representing the endometrial environment exposed to contraceptives as well as inflammatory conditions, respectively, altered the production of multiple cytokines and chemokines as compared with untreated controls. These actions of Dox occurred in cell-, ovarian steroid- and cytokine/chemokine-dependent manners. Although Dox reduced the regulatory action of steroids on the production of these cytokines/chemokines, it was less effective on TNF-alpha-treated cells.

CONCLUSIONS

The results support the hypothesis that Dox, by modulating the endometrial expression of multiple inflammatory-related cytokines/chemokines in a cell- and cytokine/chemokine-dependent manner, may have a therapeutic potential in patients experiencing irregular uterine bleeding, in particular in progestin-dominant contraceptive users.

Pharmacokinetics and tissue distribution of doxycycline after oral administration of single and multiple doses in horses

OBJECTIVE

To determine pharmacokinetics, safety, and penetration into interstitial fluid (ISF), polymorphonuclear leukocytes (PMNLs), and aqueous humor of doxycycline after oral administration of single and multiple doses in horses.

ANIMALS

6 adult horses.

PROCEDURE

The effect of feeding on drug absorption was determined. Plasma samples were obtained after administration of single or multiple doses of doxycycline (20 mg/kg) via nasogastric tube. Additionally, ISF, PMNLs, and aqueous humor samples were obtained after the final administration. Horses were monitored for adverse reactions.

RESULTS

Feeding decreased drug absorption. After multiple doses, mean +/- SD time to maximum concentration was 1.63 +/- 1.36 hours, maximum concentration was 1.74 +/- 0.3 microg/mL, and elimination half-life was 12.07 +/- 3.17 hours. Plasma protein binding was 81.76 +/- 2.43%. The ISF concentrations correlated with the calculated percentage of non-protein-bound drug. Maximum concentration was 17.27 +/- 8.98 times as great in PMNLs, compared with plasma. Drug was detected in aqueous humor at 7.5% to 10% of plasma concentrations. One horse developed signs of acute colitis and required euthanasia.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that doxycycline administered at a dosage of 20 mg/kg, PO, every 24 hours will result in drug concentrations adequate for killing intracellular bacteria and bacteria with minimum inhibitory concentration < or = 0.25 microg/mL. For bacteria with minimum inhibitory concentration of 0.5 to 1.0 microg/mL, a dosage of 20 mg/kg, PO, every 12 hours may be required; extreme caution should be exercised with the higher dosage until more safety data are available.

Tear fluid levels of MMP-8 are elevated in ocular rosacea--treatment effect of oral doxycycline

BACKGROUND

Ocular rosacea (OcR) is a chronic inflammatory disease especially affecting lid margins. Previous studies have shown that it is accompanied by increased levels and activation of tear fluid gelatinases. Matrix metalloproteinase 8 (MMP-8; collagenase 2) levels and activation are commonly elevated in many inflammatory conditions. Therefore we studied here whether MMP-8 concentration and activation in tear fluid are increased also in OcR, and if an oral doxycycline regimen could rectify the situation.

METHODS

Tear fluid samples were collected from 22 OcR patients and 22 healthy controls. The OcR patients were then treated with an oral doxycycline regimen for 8 weeks and tear fluid samples collected again after 4 and 8 weeks. Conjunctival brush cytology and patients' subjective symptoms were scored. MMP-8 concentrations in the tear fluid were assessed by immunofluorometric assay and the molecular forms and isoenzyme expression of MMP-8 were studied by Western immunoblotting.

RESULTS

The mean MMP-8 concentration was statistically significantly higher in OcR (156.8+/-207.4 mug/ml) than in the normal subjects (53.5+/-66.7 mug/ml) (P=0.036), but decreased to 79.2+/-141.6 mug/l and 53.6+/-75.2 mug/l after 4 and 8 weeks doxycycline treatment, respectively. There was a statistically significant difference between the untreated OcR and the MMP-8 results after 4 or 8 weeks of oral doxycycline (P=0.041 and 0.069, respectively) and the OcR patients experienced statistically significant relief of their subjective symptoms (P=0.0001) after the doxycycline regimen. Both the normal and OcR tear fluid contained the larger, 60-80 kDa highly- glycosylated polymorphonuclear leukocyte-type MMP-8 isoform in Western immunoblotting, but not the 45-55 kDa less glycosylated mesenchymal-type isoform. MMP-8 activation was in practice present only in the OcR samples, and was inhibited by oral doxycycline.

CONCLUSIONS

MMP-8 concentration and activation degree in tear fluid are increased in OcR, probably reflecting increased inflammatory activity. Doxycycline effectively reduces these pathologically excessive levels and activation of MMP-8, and relieves patients' subjective symptoms.

The Effect of Low-Dose Doxycycline Therapy in Chronic Meibomian Gland Dysfunction

PURPOSE

The aim was to investigate the effect of low dose doxycycline (20 mg) therapy in patients with chronic meibomian gland dysfunction that were refractory to conventional therapy.

METHODS

The randomized prospective study enrolled 150 patients (300 eyes) who have chronic meibomian gland dysfunction and who didn't respond to lid hygiene and topical therapy for more than 2 months. All topical therapy was stopped for at least 2 weeks prior to beginning the study. After conducting the tear break up time test (TBUT) and Schirmer test, the authors randomly divided the patients into three groups a high dose group (doxycycline, 200 mg, twice a day), a low dose group (doxycycline, 20 mg, twice a day) and a control group (placebo). After one month, the author repeated the TBUT and Schirmer tests, and analyzed the degree of symptomatic improvement.

RESULTS

Compared to the control group, both the high and low dose group showed statistically significant differences after treatment in TBUT, Schirmer test, the number of symptoms reported and the degree of improvement of subjective symptoms. However, there was no statistically significant difference between the high and low dose group after treatment in TBUT (9.42 +/- 2.87 sec, 9.54 +/- 1.58 sec, p=0.726), Schirmer test (19.98 +/- 4.05 mm, 19.65 +/- 5.02 mm, p=0.624), the number of symptoms reported (1.45 +/- 0.62, 1.53 +/- 0.52, p=0.304), as well as the degree of improvement of subjective symptoms (p=0.288). The high dose group (18 patients, 39.13%) reported side effects more frequently than did the low dose group (8 patients, 17.39%) (P=0.002).

CONCLUSIONS

Low dose doxycycline (20 mg twice a day) therapy was effective in patients with chronic meibomian gland dysfunction that were refractory to conventional therapy.