The effects of enrofloxacin on decorin and glycosaminoglycans in avian tendon cell cultures

Toxicologic effect of short-term enrofloxacin exposure on brain of Carassius auratus var. Pengze

To further explore short-term exposure of enrofloxacin (ENR) induced toxicity in crucian carp brain that has been reported by our previous work, as well as the possible toxicological mechanisms, this study investigated the blood-brain barrier (BBB) permeability to low dosage of ENR through comprehensively assessing expression of BBB constitutive molecules zonula occludens-1 (ZO-1) and permeability glycoprotein (P-gp), as well as ENR residue in brain of crucian carp. Toxicologic effect of ENR on brain tissue was determined through evaluating expression of brain-derived proteins S100B, neuron specific enolase (NSE) and glial fibrillary acidic protein (GFAP) in crucian carp brain tissue, as well as contents of the proteins in serum. The toxicological mechanisms were explored through analyzing transcriptome analysis data. Results showed that ENR possessed excellent permeability to crucian carp BBB, which was closely related to deranged BBB structure and declined ENR efflux that were attributed to downregulated expression of ZO-1 and P-gp by ENR exposure. Meanwhile, S100B, NSE and GFAP were upregulated in brain by ENR, and came out into blood across the damaged BBB. These data revealed that ENR induced disruption of BBB and damage of brain tissue in crucian carp. Transcriptome analysis data indicated that ENR induced toxicologic effect might be related to modification of metabolism, organismal systems, and genetic information processing, etc., and that PI3K/Akt, MAPK, HIF-1, and ubiquitin mediated proteolysis involved the mechanisms, most of the mechanisms were attributed to ENR induced oxidative stress in crucian carp brain.

Short-Term Exposure to Ciprofloxacin Reduces Proteoglycan Loss in Tendon Explants

Fluoroquinolone antibiotics are associated with increased risk of tendinopathy and tendon rupture, which can occur well after cessation of treatment. We have previously reported that the fluoroquinolone ciprofloxacin (CPX) reduced proteoglycan synthesis in equine tendon explants. This study aimed to determine the effects of CPX on proteoglycan catabolism and whether any observed effects are reversible. Equine superficial digital flexor tendon explant cultures were treated for 4 days with 1, 10, 100 or 300 µg/mL CPX followed by 8 days without CPX. The loss of [³⁵S]-labelled proteoglycans and chemical pool of aggrecan and versican was studied as well as the gene expression levels of matrix-degrading enzymes responsible for proteoglycan catabolism. CPX suppressed [³⁵S]-labelled proteoglycan and total aggrecan loss from the explants, although not in a dose-dependent manner, which coincided with downregulation of mRNA expression of MMP-9, -13, ADAMTS-4, -5. The suppressed loss of proteoglycans was reversed upon removal of the fluoroquinolone with concurrent recovery of MMP and ADAMTS mRNA expression, and downregulated TIMP-2 and upregulated TIMP-1 expression. No changes in MMP-3 expression by CPX was observed at any stage. These findings suggest that CPX suppresses proteoglycan catabolism in tendon, and this is partially attributable to downregulation of matrix-degrading enzymes.

Toxicity induced by ciprofloxacin and enrofloxacin: oxidative stress and metabolism

Ciprofloxacin (CIP) (human use) and enrofloxacin (ENR) (veterinary use) are synthetic anti-infectious medications that belong to the second generation of fluoroquinolones. They have a wide antimicrobial spectrum and strong bactericidal effects at very low concentrations via enzymatic inhibition of DNA gyrase and topoisomerase IV, which are required for DNA replication. They also have high bioavailability, rapid absorption with favorable pharmacokinetics and excellent tissue penetration, including cerebral spinal fluid. These features have made them the most applied antibiotics in both human and veterinary medicine. ENR is marketed exclusively for animal medicine and has been widely used as a therapeutic veterinary antibiotic, resulting in its residue in edible tissues and aquatic environments, as well as the development of resistance and toxicity. Estimation of the risks to humans due to antimicrobial resistance produced by CIP and ENR is important and of great interest. Moreover, in rare cases due to their overdose and/or prolonged administration, the development of CIP and ENR toxicity may occur. The toxicity of these fluoroquinolones antimicrobials is mainly related to reactive oxygen species (ROS) and oxidative stress (OS) generation, besides metabolism-related toxicity. Therefore, CIP is restricted in pregnant and lactating women, pediatrics and elderly similarly ENR do in the veterinary field. This review manuscript aims to identify the toxicity induced by ROS and OS as a common sequel of CIP and ENR. Furthermore, their metabolism and the role of metabolizing enzymes were reported.

Growth Factor Roles in Soft Tissue Physiology and Pathophysiology

Repair and healing of injured and diseased tendons has been traditionally fraught with apprehension and difficulties, and often led to rather unsatisfactory results. The burgeoning research field of growth factors has opened new venues for treatment of tendon disorders and injuries, and possibly for treatment of disorders of the aorta and major arteries as well. Several chapters in this volume elucidate the role of transforming growth factor β (TGFß) in pathogenesis of several heritable disorders affecting soft tissues, such as aorta, cardiac valves, and tendons and ligaments. Several members of the bone morphogenetic group either have been approved by the FDA for treatment of non-healing fractures or have been undergoing intensive clinical and experimental testing for use of healing bone fractures and tendon injuries. Because fibroblast growth factors (FGFs) are involved in embryonic development of tendons and muscles among other tissues and organs, the hope is that applied research on FGF biological effects will lead to the development of some new treatment strategies providing that we can control angiogenicity of these growth factors. The problem, or rather question, regarding practical use of imsulin-like growth factor I (IGF-I) in tendon repair is whether IGF-I acts independently or under the guidance of growth hormone. FGF2 or platelet-derived growth factor (PDGF) alone or in combination with IGF-I stimulates regeneration of periodontal ligament: a matter of importance in Marfan patients with periodontitis. In contrast, vascular endothelial growth factor (VEGF) appears to have rather deleterious effects on experimental tendon healing, perhaps because of its angiogenic activity and stimulation of matrix metalloproteinases-proteases whose increased expression has been documented in a variety of ruptured tendons. Other modalities, such as local administration of platelet-rich plasma (PRP) and/or of mesenchymal stem cells have been explored extensively in tendon healing. Though treatment with PRP and mesenchymal stem cells has met with some success in horses (who experience a lot of tendon injuries and other tendon problems), the use of PRP and mesenchymal stem cells in people has been more problematic and requires more studies before PRP and mesenchymal stem cells can become reliable tools in management of soft tissue injuries and disorders.

Ciprofloxacin reduces tenocyte viability and proteoglycan synthesis in short-term explant cultures of equine tendon

Fluoroquinolones are an effective, broad-spectrum antibiotic used to treat an array of bacterial infections. However, they are associated with an increased risk of tendinopathy and tendon rupture even after discontinuation of treatment. This condition is known as fluoroquinolone-associated tendinopathy, the underlying mechanisms of which are poorly understood. While many factors may be involved in the pathophysiology of tendinopathies in general, changes in tenocyte metabolism and viability, as well as alteration of proteoglycan metabolism are prominent findings in the scientific literature. This study investigated the effects of ciprofloxacin, a common fluoroquinolone, on cell viability, proteoglycan synthesis, and proteoglycan mRNA expression in equine superficial digital flexor tendon explants after 96 h treatment with between 1–300 µg/mL ciprofloxacin, and again after 8 days discontinuation of treatment. Ciprofloxacin caused significant reductions in cell viability by between 25–33% at all dosages except 10 µg/mL, and viability decreased further after 8 days discontinuation of treatment. Proteoglycan synthesis significantly decreased by approximately 50% in explants treated with 100 µg/mL and 300 µg/mL, however this effect reversed after 8 days in the absence of treatment. No significant mRNA expression changes were observed after the treatment period with the exception of versican which was down-regulated at the highest concentration of ciprofloxacin. After the recovery period, aggrecan, biglycan and versican genes were all significantly downregulated in explants initially treated with 1–100 µg/mL. Results from this study corroborate previously reported findings of reduced cell viability and proteoglycan synthesis in a whole tissue explant model and provide further insight into the mechanisms underlying fluoroquinolone-associated tendinopathy and rupture. This study further demonstrates that certain ciprofloxacin induced cellular changes are not rapidly reversed upon cessation of treatment which is a novel finding in the literature.

Determination of two fluoroquinolones and their combinations with hyaluronan effect in in vitro canine cartilage explants

Background

Previous studies reported the effect of enrofloxacin (Enro) and marbofloxacin (Mar) on cell death and alteration of the key genes involved in catabolic and anabolic processes and demonstrated the beneficial effects of hyaluronan (HA) combined with fluoroquinolones (FQs) on primary canine chondrocytes. This study further determines the effects of these treatments on canine cartilage explants in both normal and interleukin-1 beta (IL-1β)-stimulated conditions.

Methods

We examined sulfate glycosaminoglycan (s-GAG) release, uronic acid (UA) content, and safranin-O staining, as well as the expression patterns of inflammatory, extracellular matrix (ECM) component and enzymes.

Results

Enro treatment alone effectively stimulated proteoglycan anabolism by increasing UA content and glycosaminoglycans (GAGs) in normal and pre-IL-1β-stimulated explant, whereas Mar showed opposite results. The combination of HA and FQs increased s-GAG release and UA content in normal explants in addition to effective down-regulated expression of MMP3. HA reduced the adverse effects of Mar by enhancing UA and GAG contents in both normal and pre-IL-1β-explants. Moreover, HA effectively induced HAS1and ACANup-regulation and reduced MMP9, TNF, PTGS2,and NFKB1 expression for a long term.

Discussion

Our results suggest the direct effects of Enro and Mar may selectively stimulate the conditioned explants to express MMP-codinggenes and promote gene expression involved in matrix production, pro-inflammatory cytokines, and cell degradation in different directions. HA successfully reduced the adverse effects of FQs by enhancing s-GAG and UA contents and down-regulated expression of MMPs.

Acute Achilles Tendon Rupture: Clinical Evaluation, Conservative Management, and Early Active Rehabilitation

The Achilles tendon (AT) is the strongest, largest, and most commonly ruptured tendon in the human body. Physical examination provides high sensitivity and specificity. Imaging studies are not recommended unless there are equivocal findings in the physical examination. Recent studies have shown that the risk of re-rupture is negated with implementation of functional rehabilitation protocols. Heterogeneity in study design makes conclusions on the specifics of functional rehabilitation protocols difficult; however, it is clear that early weight bearing and early controlled mobilization lead to better patient outcome and satisfaction in both surgically and conservatively treated populations.

Drugs affecting glycosaminoglycan metabolism

Glycosaminoglycans (GAGs) are charged polysaccharides ubiquitously present at the cell surface and in the extracellular matrix. GAGs are crucial for cellular homeostasis, and their metabolism is altered during pathological processes. However, little consideration has been given to the regulation of the GAG milieu through pharmacological interventions. In this review, we provide a classification of small molecules affecting GAG metabolism based on their mechanism of action. Furthermore, we present evidence to show that clinically approved drugs affect GAG metabolism and that this could contribute to their therapeutic benefit.

Cytotoxic effects and apoptosis induction of enrofloxacin in hepatic cell line of grass carp (Ctenopharyngodon idellus)

We determined the effect of enrofloxacin on the lactate dehydrogenase (LDH) release, reactive oxygen species (ROS), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), malondialdehyde (MDA), mitochondria membrane potential (ΔΨm) and apoptosis in the hepatic cell line of grass carp (Ctenopharyngodon idellus). Cultured cells were treated with different concentrations of enrofloxacin (12.5-200 ug/mL) for 24 h. We found that the cytotoxic effect of enrofloxacin was mediated by apoptosis, and that this apoptosis occurred in a dose-dependent manner. The doses of 50,100 and 200 μg/mL enrofloxacin increased the LDH release and MDA concentration, induced cell apoptosis and reduced the ΔΨm compared to the control. The highest dose of 200 ug/mL enrofloxacin also significantly induced apoptosis accompanied by ΔΨm disruption and ROS generation and significantly reduced T-AOC and increased MDA concentration compared to the control. Our results suggest that the dose of 200 ug/mL enrofloxacin exerts its cytotoxic effect and produced ROS via apoptosis by affecting the mitochondria of the hepatic cells of grass carp.

Proteomics perspectives in rotator cuff research: a systematic review of gene expression and protein composition in human tendinopathy

BACKGROUND

Rotator cuff tendinopathy including tears is a cause of significant morbidity. The molecular pathogenesis of the disorder is largely unknown. This review aimed to present an overview of the literature on gene expression and protein composition in human rotator cuff tendinopathy and other tendinopathies, and to evaluate perspectives of proteomics--the comprehensive study of protein composition--in tendon research.

MATERIALS AND METHODS

We conducted a systematic search of the literature published between 1 January 1990 and 18 December 2012 in PubMed, Embase, and Web of Science. We included studies on objectively quantified differential gene expression and/or protein composition in human rotator cuff tendinopathy and other tendinopathies as compared to control tissue.

RESULTS

We identified 2199 studies, of which 54 were included; 25 studies focussed on rotator cuff or biceps tendinopathy. Most of the included studies quantified prespecified mRNA molecules and proteins using polymerase chain reactions and immunoassays, respectively. There was a tendency towards an increase of collagen I (11 of 15 studies) and III (13 of 14), metalloproteinase (MMP)-1 (6 of 12), -9 (7 of 7), -13 (4 of 7), tissue inhibitor of metalloproteinase (TIMP)-1 (4 of 7), and vascular endothelial growth factor (4 of 7), and a decrease in MMP-3 (10 of 12). Fourteen proteomics studies of tendon tissues/cells failed inclusion, mostly because they were conducted in animals or in vitro.

CONCLUSIONS

Based on methods, which only allowed simultaneous quantification of a limited number of prespecified mRNA molecules or proteins, several proteins appeared to be differentially expressed/represented in rotator cuff tendinopathy and other tendinopathies. No proteomics studies fulfilled our inclusion criteria, although proteomics technologies may be a way to identify protein profiles (including non-prespecified proteins) that characterise specific tendon disorders or stages of tendinopathy. Thus, our results suggested an untapped potential for proteomics in tendon research.

In vitro changes in human tenocyte cultures obtained from proximal biceps tendon: multiple passages result in changes in routine cell markers

PURPOSE

Results of in vitro cell models are commonly used to promote new therapies (e.g., platelet-rich plasma), and clinicians have to be aware of the specific limitations of such models. To gain a sufficient and effective cell load, many current in vitro models use cells multiplied through various passages. This is especially important in tendon-like cell (TLC) models, since native tendon tissue is not available unlimited and contains limited amount of tenocytes. The purpose was to determine the occurrence of phenotypic changes following extended monolayer culture of TLCs, according to cell-passage number.

METHODS

Tendon samples were obtained from 15 healthy patients undergoing biceps tenodesis. Tendons were digested and cultured (monolayer) for six passages. Tendon-specific markers (collagens I and III, decorin, tenascin-C, and tenomodulin) and their histology were analyzed using gene expression and protein content assays. Native cells, the cells cultured and cells passaged one to six times were analyzed at each passage.

RESULTS

Gene expression of types I and III collagen of cultured TLCs significantly decreased after two passages. Gene expression of decorin, tenascin-C, and tenomodulin exhibited a trend of decreased gene expression with increased passage. Protein levels of types I and III collagen and decorin decreased after four passages.

CONCLUSIONS

The significant findings let conclude that tenocyte-like cells obtained from human LHB can be maintained in monolayer culture at low passages, before the signs of phenotypic drift are present. But researchers must be aware of rapid phenotypic drift at higher passage numbers. Therefore, only cells within the first 3 passages should be used as a precaution for in vitro monolayer cell models, and one has to be aware of the phenotypic changes if TLCs passaged multiple times are used. The clinical relevance of this data is that understanding of in vitro TLC models, and their limitations may finally help the clinician to judge the potential of experimental data of new biologic treatment options.

Adverse effects of antimicrobials via predictable or idiosyncratic inhibition of host mitochondrial components

This minireview explores mitochondria as a site for antibiotic-host interactions that lead to pathophysiologic responses manifested as nonantibacterial side effects. Mitochondrion-based side effects are possibly related to the notion that these organelles are archaic bacterial ancestors or commandeered remnants that have co-evolved in eukaryotic cells; thus, this minireview focuses on mitochondrial damage that may be analogous to the antibacterial effects of the drugs. Special attention is devoted to aminoglycosides, chloramphenicol, and fluoroquinolones and their respective single side effects related to mitochondrial disturbances. Linezolid/oxazolidinone multisystemic toxicity is also discussed. Aminoglycosides and oxazolidinones are inhibitors of bacterial ribosomes, and some of their side effects appear to be based on direct inhibition of mitochondrial ribosomes. Chloramphenicol and fluoroquinolones target bacterial ribosomes and gyrases/topoisomerases, respectively, both of which are present in mitochondria. However, the side effects of chloramphenicol and the fluoroquinolones appear to be based on idiosyncratic damage to host mitochondria. Nonetheless, it appears that mitochondrion-associated side effects are a potential aspect of antibiotics whose targets are shared by prokaryotes and mitochondria-an important consideration for future drug design.

Small leucine-rich proteoglycans, decorin and fibromodulin, are reduced in postburn hypertrophic scar

Small leucine-rich proteoglycans (SLRPs) are extracellular matrix molecules that regulate collagen fibrillogenesis and inhibit transforming growth factor-β activity; thus, they may play a critical role in wound healing and scar formation. Hypertrophic scarring is a dermal form of fibroproliferative disorders, which occurs in over 70% of burn patients and leads to disfigurement and limitations in function. By understanding the cellular and molecular mechanisms that lead to scarring after injury, new clinical therapeutic approaches can by developed to minimize abnormal scar formation in hypertrophic scarring and other fibroproliferative disorders. To study the expression and localization of SLRPs with connective tissue cells in tissue immunohistochemistry, immunofluorescence staining, immunoblotting, and reverse-transcription polymerase chain reaction were used in normal skin and hypertrophic scar (HTS). In normal skin, there was more decorin and fibromodulin accumulation in the superficial layers than in the deeper dermal layers. The levels of decorin and fibromodulin were significantly lower in HTS, whereas biglycan was increased when compared with normal skin. There was an increased expression of biglycan, fibromodulin, and lumican in the basement membrane and around basal epithelial cells. In contrast, these proteoglycans were absent or weakly expressed in HTS. The findings suggest that down-regulation of SLRPs after wound healing in deep injuries to the skin plays an important role in the development of fibrosis and HTS.

Effects of activity on avian gastrocnemius tendon

Physical activity and its relationship to animal health is a continuous concern of the food animal industry. This study investigated the relationship between broiler (meat-type chicken) activity to the structural integrity of the gastrocnemius tendon. Birds were exposed to treadmill pacing to determine if increased mobilization would increase tendon strength and improve its resistance to soft tissue injury. One hundred eighty broilers raised under normal commercial housing conditions were forced to walk on a treadmill 30 min/d, 5 d/wk for 3 wk, beginning at 3 wk of age. The treadmill treatment did affect the growth rate of the broilers. At the end of the study, the average body mass of the treatment birds was 9% less than the average body mass of the control birds, and the average length of the treatment shanks was 5% less than those from the control birds. Biomechanical parameters were measured and used to determine changes in the structural and material integrity of the tendons. The treadmill treatment did not affect tendon toughness, stiffness, relaxation behavior, and failure strength, but treatment did appear to affect tendon geometry, in which 33% of the treadmill treatment tendons had an increased amount of tissue near the bifurcation. The treadmill treatment did not affect the amount of procollagen within the tendon, and no cellular anomalies were found.

Age-dependent effects on redox status, oxidative stress, mitochondrial activity and toxicity induced by fluoroquinolones on primary cultures of rabbit tendon cells

The age-related difference in fluoroquinolone-induced tendon toxicity was investigated. In vitro tendon cells from juvenile and young adult rabbits, respectively, were incubated with quinolone (nalidixic acid, NA) or fluoroquinolone (ofloxacin, OFX or pefloxacin, PEF) at 0.01 microM to 1 mM for 72 h. Redox status, glutathione (GSH), reactive oxygen species (ROS), and mitochondrial activity were assessed using intracellular fluorescent probes. Fluorescence signal was detected on living adherent tenocytes in microplates using cold-light cytofluorometry. Tendon toxicity differed significantly between the two cell groups and the difference was greatest with highest dose (1 mM). For 72 h, significant (p < 0.001) differences between immature and young adult primary tenocytes were observed for redox status decrease, GSH decrease, and ROS production increase. Mitochondrial activity remained unaltered in immature tenocytes. We confirm two groups of intrinsic tendon toxicity (OFX/NA vs. PEF) associated to oxidative stress (GSH decrease). Our in vitro experimental model confirms the clinical observations of age dependent tenotoxicity. First group (NA, OFX) showed greater intrinsic tenotoxicity for young adult than immature tenocytes, second group (PEF) was highly toxic for immature and young adult cells. The three quinolones do not altered mitochondrial activity in immature tenocytes whereas alteration was observed in young adult tenocytes.

Acute rupture of the Achilles tendon

Achilles tendon ruptures are common, and their incidence is increasing. The evidence for best management is controversial, and, in selected patients, conservative management and early mobilization achieves excellent results. Surgery is associated with an increased risk of superficial skin breakdown; however, modern techniques of percutaneous repair that are performed under local anesthesia and followed by early functional rehabilitation are becoming increasingly common, and should be considered when managing such patients.

Fluoroquinolones and tendon disorders

Fluoroquinolones are the most potent oral antibiotics in clinical use today. Increasingly, these drugs are being prescribed for relatively benign infections and for new categories of patients, including paediatric patients. As their use becomes more frequent, so will the adverse events. This review focuses on a rare but debilitating adverse reaction, the fluoroquinolone-associated tendinopathy. Despite many published case reports and approximately 3500 cases reported to the World Health Organization Collaborating Centre for Drug Monitoring, little is known about the mechanisms behind this fluoroquinolone-specific toxicity. Data on chemical properties, mode of action, pharmacokinetic features, clinical presentation and risk factors in relation to tendon toxicity are discussed and the literature reviewed. As long as the musculoskeletal toxicity cannot be predicted by in vitro or in vivo models and this class of antibiotics is one of the most commonly linked to selection of resistant bacteria, a more prudent use of fluoroquinolones is warranted.