Pathophysiology of cyclooxygenase inhibition in animal models

Measurement of Cyclooxygenase Products in Plasma as Markers for Inhibition of Cyclooxygenase Isoforms by Oral Meloxicam in New Zealand White Rabbits (Oryctolagus cuniculus )

Pain management in rabbits is a challenging task that is complicated by the rabbit's ability to hide signs of distress and the limited pharmacologic data available for this species. Pharmacokinetic data has shown that in rabbits, meloxicam, a nonsteroidal anti-inflammatory NSAID, reaches plasma concentrations that are known to provide analgesia in dogs and cats; these concentrations could theoretically alleviate pain in rabbits. However, the inhibitory effects of meloxicam on cyclooxygenase (COX) isoforms have not been studied in rabbits. In this study, we measured the products of COX-1 and COX-2 after the oral administration of a single 1 mg/kg dose of meloxicam to New Zealand White rabbits (n = 6). Blood samples were collected before drug administration (T0) and then at predetermined time points over 48 h. Plasma prostaglandin E₂ (PGE₂ ) and thromboxane (TxB₂) concentrations were measured as surrogate markers for COX-1 and COX-2, respectively, by using commercial ELISA kits. After meloxicam administration, both TxB₂ and PGE₂ plasma concentrations fell significantly below baseline, with maximal mean reductions to 80% and 60% of baseline at 8 h, respectively. The reduction in PGE₂ concentrations was followed by a significant increase that moved its mean plasma concentrations toward baseline between 8 and 24 h. Adverse effects such as lethargy, inappetence, or changes in fecal production were not observed in any rabbits. In conclusion, meloxicam appeared to significantly inhibit both COX-1 and COX-2 with a time course similar to previously reported meloxicam plasma concentration-time profiles in rabbits. Our data suggest that a dosage of 1 mg/kg given orally could provide analgesia to rabbits, but a more frequent dosing interval than the currently recommended daily dosing may be required to maintain clinical efficacy.

Identification of Candidate Genes Associated With Hypoxia Tolerance in Trachinotus blochii Using Bulked Segregant Analysis and RNA-Seq

Golden Pompano (Trachinotus blochii) has rapidly developed into the one of the main valuable fish species in Chinese marine aquaculture. Due to its rapid growth, active metabolism, and high oxygen consumption, hypoxia will increase its mortality and cause serious economic losses. We constructed two experimental groups of fish with different degrees of tolerance to hypoxia, used BSR-Seq analysis based on genome and genetic linkage groups to locate SNPs and genes that were related to the differences in hypoxia tolerance. The results showed that hypoxia tolerance SNPs of golden pompano may be jointly determined by multiple linkage groups, especially linkage groups 18 and 22. There were 768 and 348 candidate genes located in the candidate regions of the brain and liver, respectively. These genes were mainly involved in anaerobic energy metabolism, stress response, immune response, waste discharge, and cell death. The prostaglandin-endoperoxide synthase 2 (PTGS2) on LG8, which is involved in the metabolism of arachidonic acid, has a G/A nonsynonymous mutation at position 20641628, and the encoded amino acid was changed from hydrophobic aspartic acid to asparaginate. The specific pathway of the RIG-I-like receptor signaling pathway in the liver may mediate the metabolic system and the immune system, linking glucose metabolism with immune regulation. The death of the hypoxia-intolerant group may be due to the accumulation of lactic acid caused by the activation of anaerobic glycolysis during the early stage of hypoxia stress, and the activation of type I interferon was inhibited, which resulted in decreased immunity. Among the genes involved in the RIG-I-like receptor signaling pathway, the CYLD Lysine 63 Deubiquitinase (CYLD) located on LG16 had a G/T nonsynonymous mutation at position 13629651, and the encoded amino acid was changed from alanine acid to valine. The interferon induced with helicase C domain 1 (Ifih1) located on LG18 has a G/C nonsynonymous mutation at position 16153700, and the encoded hydrophilic glycine was changed to hydrophobic alanine. Our findings suggest these SNPs may assist in the molecular breeding of hypoxia-tolerant golden pompano, and speculate that the balance of glucose and lipid metabolism plays a key role in Trachinotus blochii under acute hypoxia.

Immunopathogenicity of Acanthamoeba spp. in the Brain and Lungs

Free-living amoebas, including Acanthamoeba spp., are widely distributed in soil, water, and air. They are capable of causing granulomatous amebic encephalitis, Acanthamoeba pneumonia, Acanthamoeba keratitis, and disseminated acanthamoebiasis. Despite low occurrence worldwide, the mortality rate of Acanthamoeba spp. infections is very high, especially in immunosuppressed hosts. Acanthamoeba infections are a medical problem, owing to limited improvement in diagnostics and treatment, which is associated with incomplete knowledge of pathophysiology, pathogenesis, and the host immune response against Acanthamoeba spp. infection. The aim of this review is to present the biochemical and molecular mechanisms of Acanthamoeba spp.-host interactions, including the expression of Toll-like receptors, mechanisms of an immune response, the activity of metalloproteinases, the secretion of antioxidant enzymes, and the expression and activity of cyclooxygenases. We show the relationship between Acanthamoeba spp. and the host at the cellular level and host defense reactions that lead to changes in the selected host's organs.

An adverse outcome pathway for immune-mediated and allergic hepatitis: a case study with the NSAID diclofenac

Many drugs have the potential to cause drug-induced liver injury (DILI); however, underlying mechanisms are diverse. The concept of adverse outcome pathways (AOPs) has become instrumental for risk assessment of drug class effects. We report AOPs specific for immune-mediated and drug hypersensitivity/allergic hepatitis by considering genomic, histo- and clinical pathology data of mice and dogs treated with diclofenac. The findings are relevant for other NSAIDs and drugs undergoing iminoquinone and quinone reactive metabolite formation. We define reactive metabolites catalyzed by CYP monooxygenase and myeloperoxidases of neutrophils and Kupffer cells as well as acyl glucuronides produced by uridine diphosphoglucuronosyl transferase as molecular initiating events (MIE). The reactive metabolites bind to proteins and act as neo-antigen and involve antigen-presenting cells to elicit B- and T-cell responses. Given the diverse immune systems between mice and dogs, six different key events (KEs) at the cellular and up to four KEs at the organ level are defined with mechanistic plausibility for the onset and progression of liver inflammation. With mice, cellular stress response, interferon gamma-, adipocytokine- and chemokine signaling provided a rationale for the AOP of immune-mediated hepatitis. With dogs, an erroneous programming of the innate and adaptive immune response resulted in mast cell activation; their infiltration into liver parenchyma and the shift to M2-polarized Kupffer cells signify allergic hepatitis and the occurrence of granulomas of the liver. Taken together, diclofenac induces divergent immune responses among two important preclinical animal species, and the injury pattern seen among clinical cases confirms the relevance of the developed AOP for immune-mediated hepatitis.

Ultrasound-guided psoas compartment and sciatic nerve blocks for pain management of hind limb procedures in the alpaca (Vicugna pacos)

Background:

Loco-regional anesthetic techniques are considered important in the multimodal approach to analgesia in both human and veterinary medicine. No such techniques are described in the alpaca, bar the use of epidural. This is in part due to the lack of anatomical description for this species. While this limitation exists, the use of ultrasound guidance makes peripheral nerve blocks a viable possibility in the alpaca.

Case description:

A 12-month-old alpaca was referred for the treatment of a septic left tarso-crural joint. Due to a poor prognosis, amputation of the limb under general anesthesia was performed. Sciatic and psoas compartment blocks were attempted with the ultrasound-guided injection of ropivacaine prior to the start of the procedure. While the femoral nerve was possible to visualize, no obturator nerve was identified. A 5-year old alpaca was also referred for a left hind lateral claw removal, due to a squamous cell carcinoma. The sciatic nerve block was performed prior to the claw amputation under general anesthesia. No changes in heart and respiratory rate, or blood pressure suggestive of nociception, were observed in either of these cases. At the end of both the procedures, the patients experienced uneventful recoveries characterized by the ability to maintain the standing position, interest in food, and normal behavior.

Conclusion:

This report identifies the ease of performance and the challenges encountered using the ultrasound-guided psoas compartment and sciatic nerve blocks in the alpaca. It is our hope that this report encourages the use of ultrasound-guided loco-regional techniques in this species.

Cardio-renal safety of non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used therapeutic class in clinical medicine. These are sub-divided based on their selectivity for inhibition of cyclooxygenase (COX) isoforms (COX-1 and COX-2) into: (1) non-selective (ns-NSAIDs), and (2) selective NSAIDs (s-NSAIDs) with preferential inhibition of COX-2 isozyme. The safety and pathophysiology of NSAIDs on the renal and cardiovascular systems have continued to evolve over the years following short- and long-term treatment in both preclinical models and humans. This review summarizes major learnings on cardiac and renal complications associated with pharmaceutical inhibition of COX-1 and COX-2 with focus on preclinical to clinical translatability of cardio-renal data.

Kidney Pathophysiology, Toxicology, and Drug-Induced Injury in Drug Development

Anatomically, the kidneys are paired, bean-shaped (in most mammals), excretory organs that lie in the retroperitoneum. High blood flow to the kidneys, together with high oxygen consumption, makes them more vulnerable to exposure, via the circulation, and subsequent injury related to high concentrations of xenobiotics and chemicals. In preclinical drug development and safety assessment of new investigational drugs, changes in kidney structure and/or function following drug administration in experimental laboratory animals need to be put in context with interspecies differences in kidney functional anatomy, physiology, spontaneous pathologies, and toxicopathological responses to injury. In addition, translation to human relevance to avoid premature drug termination from development is vital. Thus, detection and characterization of kidney toxicity in preclinical species and human relevance will depend on the preclinical safety testing strategy and collective weight-of-evidence approach including new investigational drug mechanism of action (MOA), preclinical and clinical interspecies differences, and MOA relevance to humans. This review describes kidney macroscopic and microscopic functional anatomy, physiology, pathophysiology, toxicology, and drug-induced kidney toxicities in safety risk assessment and drug development.

Immunopathogenesis of Acute Kidney Injury

Pathophysiologically, the classification of acute kidney injury (AKI) can be divided into three categories: (1) prerenal, (2) intrinsic, and (3) postrenal. Emerging evidence supports the involvement of renal tubular epithelial cells and the innate and adaptive arms of the immune system in the pathogenesis of intrinsic AKI. Pro-inflammatory damage-associated molecular patterns, pathogen-associated molecular patterns, hypoxia inducible factors, toll-like receptors, complement system, oxidative stress, adhesion molecules, cell death, resident renal dendritic cells, neutrophils, T and B lymphocytes, macrophages, natural killer T cells, cytokines, and secreted chemokines contribute to the immunopathogenesis of AKI. However, other immune cells and pathways such as M2 macrophages, regulatory T cells, progranulin, and autophagy exhibit anti-inflammatory properties and facilitate kidney tissue repair after AKI. Thus, therapies for AKI include agents such as anti-inflammatory (e.g., recombinant alkaline phosphatase), antioxidants (iron chelators), and apoptosis inhibitors. In preclinical toxicity studies, drug-induced kidney injury can be seen after exposure to a nephrotoxicant test article due to immune mechanisms and dysregulation of innate, and/or adaptive cellular immunity. The focus of this review will be on intrinsic AKI, as it relates to the immune and renal systems cross talks focusing on the cellular and pathophysiologic mechanisms of AKI.

Comparison of post-operative analgesic efficacy of tolfenamic acid and robenacoxib in ovariohysterectomized cats

The objective of this study was to evaluate the efficacy of a non-selective COX inhibitor (tolfenamic acid) and a selective COX-2 inhibitor (robenacoxib) for post-operative pain control in cats. Thirty cats undergoing ovariohysterectomy were randomly divided into three groups: the control (placebo) group, the tolfenamic acid (4 mg/kg/day) group, and the robenacoxib (1 mg/kg/day) group. Non-steroidal anti-inflammatory drugs (NSAIDs) were administered orally 2 hr before anesthesia induction and 24 and 48 hr post-operation. Buccal mucosal bleeding times (BMBTs) were assessed prior to anesthesia induction. Colorado pain scores and composite pain scores were evaluated in a blinded fashion before induction and 2, 8, 24, 30 and 48 hr post-operation. The Colorado pain scores of cats receiving robenacoxib were significantly lower than those of cats in the control group at 30 (P=0.0126) and 48 (P=0.0439) hr post-operation. The composite pain scores of cats from the robenacoxib group were lower than those of cats in the control group at 30 (P=0.0299) and 48 (P=0.0103) hr post-operation. The Colorado pain scores of cats receiving tolfenamic acid were significantly lower than those of cats in the control group at 30 hr (P=0.0186) post-operation. The composite pain scores in cats in the tolfenamic acid group were lower than the scores of cats in the control group at 24 (P=0.0403) and 48 (P=0.0413) hr post-operation. BMBTs remained within normal limits in all groups. Both tolfenamic acid and robenacoxib are useful for post-operative pain control in cats.

Expression and Activity of COX-1 and COX-2 in Acanthamoeba sp.-Infected Lungs According to the Host Immunological Status

Little is known about the pathomechanism of pulmonary infections caused by Acanthamoeba sp. Therefore, the aim of this study was to determine whether Acanthamoeba sp. may affect the expression and activity of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), resulting in the altered levels of their main products, prostaglandins (PGE₂) and thromboxane B₂ (TXB₂), in lungs of immunocompetent or immunosuppressed hosts. Acanthamoeba sp. induced a strong expression of COX-1 and COX-2 proteins in the lungs of immunocompetent mice, which, however, did not result in significant differences in the expression of PGE₂ and TXB₂. Our immunohistochemical analysis showed that immunosuppression induced by glucocorticoids in Acanthamoeba sp.-infected mice caused a decrease in COX-1 and COX-2 (not at the beginning of infection) in lung tissue. These results suggest that similar to COX-2, COX-1 is an important mediator of the pathophysiology in experimental pulmonary acanthamoebiasis. We suggest that the signaling pathways important for Acanthamoeba sp. induction of lung infection might interact with each other and depend on the host immune status.

Cyclooxygenase-2 expression in the eyes of cats with and without uveitis

OBJECTIVE To characterize the distribution and intensity of cyclooxygenase (COX)-2 expression in the eyes of cats with and without uveitis and to determine whether COX-2 expression is correlated with severity of inflammation. SAMPLES Archived ocular tissue specimens from 51 cats with and 10 cats without ocular disease. PROCEDURES Specimens from only 1 eye were evaluated for each cat. Specimens were stained with H&E stain or immunohistochemical stain for detection of COX-2 and reviewed. For each eye, the type, severity, and distribution of inflammation and the distribution and intensity of COX-2 expression were determined for the uvea and other ocular tissues. Correlation between COX-2 expression and inflammation severity was also assessed. RESULTS COX-2 was not expressed in any nondiseased eye. Of the 51 diseased eyes, 20 had histologic evidence of lymphocytic-plasmacytic uveitis, 13 had neutrophilic uveitis, 11 had diffuse iris melanoma with uveitis, and 7 had diffuse iris melanoma without uveitis. Of the 44 eyes with uveitis, COX-2 was detected in the uvea of 16, including 11 eyes with lymphocytic-plasmacytic uveitis, 4 with neutrophilic uveitis, and 1 with diffuse iris melanoma-induced uveitis. Inflammation was severe, moderate, or mild in 10, 5, and 1 of those eyes, respectively. Cyclooxygenase-2 was detected in the cornea of 21 eyes with uveitis and 1 eye with diffuse iris melanoma without uveitis. Uveitis severity was positively correlated with COX-2 expression in both the uvea and cornea. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that COX-2 is an inflammatory mediator in feline uveitis but not diffuse iris melanoma.

Suppression of calpain expression by NSAIDs is associated with inhibition of cell migration in rat duodenum

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for the alleviation of pain and inflammation, but these drugs are also associated with a suite of negative side effects. Gastrointestinal (GI) toxicity is particularly concerning since it affects an estimated 70% of individuals taking NSAIDs routinely, and evidence suggests the majority of toxicity is occurring in the small intestine. Traditionally, NSAID-induced GI toxicity has been associated with indiscriminate inhibition of cyclooxygenase isoforms, but other mechanisms, including inhibition of cell migration, intestinal restitution, and wound healing, are likely to contribute to toxicity. Previous efforts demonstrated that treatment of cultured intestinal epithelial cells (IEC) with NSAIDs inhibits expression and activity of calpain proteases, but the effects of specific inhibition of calpain expression in vitro or the effects of NSAIDs on intestinal cell migration in vivo remain to be determined. Accordingly, we examined the effect of suppression of calpain protease expression with siRNA on cell migration in cultured IECs and evaluated the effects of NSAID treatment on epithelial cell migration and calpain protease expression in rat duodenum. Our results show that calpain siRNA inhibits protease expression and slows migration in cultured IECs. Additionally, NSAID treatment of rats slowed migration up the villus axis and suppressed calpain expression in duodenal epithelial cells. Our results are supportive of the hypothesis that suppression of calpain expression leading to slowing of cell migration is a potential mechanism through which NSAIDs cause GI toxicity.

The renal effects of NSAIDs in dogs

The quality of life for dogs with osteoarthritis can often be improved with nonsteroidal anti-inflammatory drugs (NSAIDs); however, the number of adverse drug events associated with NSAID use reported to the Federal Drug Administration Center for Veterinary Medicine is higher than that for any other companion animal drug. Of those events, adverse renal reactions are the second most reported. NSAIDs produce pharmacologic effects via inhibition of cyclooxygenase (COX), which decreases production of prostanoids. Prostaglandins are synthesized by both the COX-1 and COX-2 enzymes in the healthy kidney and influence renal blood flow, glomerular filtration rate, renin release, and Na excretion. There are important species differences in the renal expression of COX-1 and COX-2. For example, dogs have higher basal levels of COX-2 expression in the kidney compared with humans. In addition, in dogs with chronic kidney disease, an increase in COX-2 expression occurs and synthesis of prostaglandins shifts to the COX-2 pathway. For those reasons, NSAIDs that target COX-2 may be expected to adversely affect renal function in dogs, especially dogs with chronic kidney disease. The purpose of this review was to evaluate the literature to report the renal effects of NSAIDs in dogs.

Consumer self-selection, safety, and compliance with a novel over-the-counter ibuprofen 600-mg immediate-release and extended-release tablet

OBJECTIVE

The extent to which people comply with labeled instructions for use of long-acting over-the-counter analgesics is largely unknown; this study evaluated whether consumers can correctly select and use a new long-acting ibuprofen 600-mg immediate-release and extended-release (IR/ER) product.

DESIGN

A single open-label study with participants randomly assigned to 2 substudies. Self-selection substudy: participants estimated duration of their last pain episode, then selected ibuprofen IR/ER or standard ibuprofen IR for a similar episode. Compliance substudy: participants purchased and recorded real-world use of ibuprofen IR/ER in daily diaries over 30 days.

SETTING

Eighteen U.S. pharmacies.

PARTICIPANTS

Consumers age 12 years or older who used an average of ≥5 doses per month of an over-the-counter analgesic in the past 3 months.

INTERVENTION

Self-selection: questionnaire only. Compliance: ibuprofen IR/ER as needed.

MAIN OUTCOME MEASURES

Self-selection: percentage who correctly selected or avoided selecting ibuprofen IR/ER based on anticipated pain duration. Compliance: proportion who were excessive users (use for >10 of 30 days and averaging >1600 mg/d, or >20 tablets over ≤10 days and averaging >1600 mg/d).

RESULTS

Self-selection substudy (N = 249): on the primary endpoint, 69.1% (95% confidence interval [CI], 63.3%-74.8%) overall made a correct selection-63.5% (95% CI, 57.5%-69.4%) correctly selected ibuprofen IR/ER for pain ≥6 hours and 5.6% (95% CI, 2.8%-8.5%) correctly avoided selecting ibuprofen IR/ER for shorter-lasting pain. Overall, 82.7% (95% CI, 77.6%-87.8%) chose correctly when subjects who picked ibuprofen IR for pain ≥6 hours (a "missed opportunity," not an incorrect selection) were excluded. Compliance substudy (N = 405): only 5 participants (1.2%; 95% CI, 0.2%-2.3%) were excessive users; all took ibuprofen IR/ER for >10 days, averaging 1821 mg/day (range, 1661.5-2072.7 mg/d). No excessive user experienced an adverse event.

CONCLUSION

Although the study did not meet the a priori primary efficacy outcome target, the majority of participants selected and used ibuprofen 600-mg IR/ER tablets correctly per the labeled instructions.

Immunohistochemical Labelling for Cyclo-oxygenase-2: Does the Positive Control Guarantee Standardized Results?

Since the identification of cyclo-oxygenase-2 as a potentially important therapeutic target in veterinary oncology, numerous studies on its expression have been conducted. Unfortunately, results have been heterogeneous and conclusions are difficult to draw. We tested the ability of a defined positive control to guarantee reproducibility of results among different laboratories. Valid positive controls were defined by positivity of the renal macula densa without background labelling. Fifteen colorectal tumours and 15 oral squamous cell carcinomas were labelled immunohistochemically by six European laboratories. Slides were evaluated in blinded fashion for percentage of positive cells and labelling intensity by three pathologists, and results were analyzed statistically for reproducibility and inter-reader variability. Macula densa positivity was an insufficiently sensitive control to guarantee reproducible results for percentage of positive cells and labelling intensity. Inter-reader variability was proven statistically, making the case for image analysis or other automated quantitative evaluation techniques.

Modulation of intestinal afferent nerve sensitivity to inflammatory mediators following systemic endotoxin in mice

BACKGROUND

Endotoxin exposure may be followed by visceral hypersensitvity but potential mechanisms are not fully explored. We aimed to test the hypothesis that mast cells and the cyclooxygenase pathway (COX) mediate modulation of afferent nerve sensitivity following systemic endotoxin.

METHODS

C57Bl6 mice received endotoxin injection i.p. to induce systemic inflammation. Control animals received normal saline. Extracellular multi-unit afferent nerve discharge was recorded from jejunal mesenteric nerves in vitro. Afferent nerve response to 5-hydroxytryptamine (5-HT, 250 μmol/L), bradykinin (BK, 0.5 μmol/L), and to mechanical ramp distension of the intestinal lumen from 0 to 60 cmH2O were recorded 2 h following endotoxin administration.

KEY RESULTS

Following endotoxin administration peak afferent discharge to 5-HT and BK was increased compared to controls (p < 0.05). Pre-perfusion with the mast cell stabilizer Doxantrazole (10(-4) M), or the cyclooxygenase inhibitor Naproxen inhibited the increased response to 5-HT and BK (p < 0.05 vs endotoxin pretreatment). Mechanosensitivity during luminal ramp distension from 10 to 60 cmH2O was increased following endotoxin pretreatment compared to controls (p < 0.05). This increase in sensitivity following endotoxin was no longer observed after Doxantrazole or Naproxen administration for pressures from 10 to 30 cmH2O (p < 0.05). Selective COX-2 inhibition by NS398 (10 μM) but not COX-1 inhibition by SC560 (300 μM) reduced increased afferent discharge in endotoxin pretreated animals to 5-HT, BK and mechanical ramp distension from 10 to 40 cmH2O (all p < 0.05).

CONCLUSIONS & INFERENCES

Systemic endotoxin sensitizes mesenteric afferent nerve fibers to 5-HT, BK and mechanical stimuli. The underlying mechanism responsible for this sensitization seems to involve mast cells and the COX-2 pathway.

Comparative assessment of effectiveness of ketoprofen and ketoprofen/beta-cyclodextrin complex in two experimental models of inflammation in rats

Oral administration of non-steroidal anti-inflammatory drugs (NSAIDs) can lead to adverse effects such as gastrointestinal distress. The complexation of different groups of active substances with β-cyclodextrin (β-CD) has drawn considerable interest over recent years. The purpose of this study was to analyze the ketoprofen/β-cyclodextrin (K/β-CD) conjugate complex as well as to assess its anti-inflammatory effect after oral administration (doses of 30 mg/m(2) and 15 mg/m(2) of body surface), compared with ketoprofen. The studies were done on two models of experimentally-induced acute inflammation in rats (n = 48, 6/group), by means of intraplantar administration of a 10% aqueous kaolin suspension and intraperitoneal administration of a 1% sodium thioglycolate solution. The dynamics of the acute inflammatory process and the anti-inflammatory effects were monitored using plethysmometric determinations after 3, 6, 9, 12, 24 and 48 h (plantar inflammation), and the absorbance of the exudates (spectrophotometrically read) and nucleated cell counts after 24 h (peritoneal inflammation). The coupling of ketoprofen with β-CD resulted in increased solubility (100% in 60 min) of the newly-formed product, which further resulted in a higher bioavailability compared with ketoprofen (<40% in 120 min). In both models of experimentally-induced inflammation, the K/β-CD complex had a higher anti-inflammatory activity than ketoprofen.

A study to compare circulating flunixin, meloxicam and gabapentin concentrations with prostaglandin E₂ levels in calves undergoing dehorning

The purpose of this study was to investigate the pharmacokinetics of intravenous flunixin (2.2 mg/kg b.w.), oral meloxicam (1mg/kg b.w.), oral gabapentin (15 mg/kg b.w.) alone or co-administrated with meloxicam as well as the effects of these compounds on prostaglandin E2 (PGE2) synthesis in calves subjected to surgical dehorning. Plasma samples collected up to 24h after drug administration were analyzed by liquid chromatography/mass spectrometry, whereas blood PGE2 levels were measured by immunoenzymatic assay. In plasma, the terminal half-live of flunixin, meloxicam and gabapentin were 6.0 h (range, 3.4-11.0 h), 16.7h (range, 13.7-21.3h) and 15.3h (range, 11-32.9h), respectively. The co-administration of single doses of gabapentin and meloxicam did not seem to affect the pharmacokinetic profile of the two drugs except for gabapentin that reached significantly (P<0.05) higher maximum serum concentration (Cmax) when co-administered with meloxicam, than when administered alone. At 5, 360 and 720 min after dehorning, a significant (P<0.01) decrease in PGE2 concentration was observed in flunixin-treated animals compared with control calves. Moreover, circulating log PGE2 concentrations were inversely proportional to log flunixin concentrations (R(2)=0.75; P<0.0001). None of the other drugs significantly affected blood PGE2 levels. Further assessment of oral meloxicam and gabapentin in established pain models is required to formulate science based analgesic recommendations to enhance animal well-being after dehorning.

MMP9 regulates the cellular response to inflammation after skeletal injury

Like other tissue injuries, bone fracture triggers an inflammatory response, which plays an important role in skeletal repair. Inflammation is believed to have both positive and negative effects on bone repair, but the underlying cellular mechanisms are not well understood. To assess the role of inflammation on skeletal cell differentiation, we used mouse models of fracture repair that stimulate either intramembranous or endochondral ossification. In the first model, fractures are rigidly stabilized leading to direct bone formation, while in the second model, fracture instability causes cartilage and bone formation. We compared the inflammatory response in these two mechanical environments and found changes in the expression patterns of inflammatory genes and in the recruitment of inflammatory cells and osteoclasts. These results suggested that the inflammatory response could influence skeletal cell differentiation after fracture. We then exploited matrix metalloproteinase 9 (MMP9) that is expressed in inflammatory cells and osteoclasts, and which we previously showed is a potential regulator of cell fate decisions during fracture repair. Mmp9(-/-) mice heal stabilized fractures via endochondral ossification, while wild type mice heal via intramembranous ossification. In parallel, we observed increases in macrophages and T cells in the callus of Mmp9(-/-) compared to wild type mice. To assess the link between the profile of inflammatory cells and skeletal cell fate functionally, we transplanted Mmp9(-/-) mice with wild type bone marrow, to reconstitute a wild type hematopoietic lineage in interaction with the Mmp9(-/-) stroma and periosteum. Following transplantation, Mmp9(-/-) mice healed stabilized fractures via intramembranous ossification and exhibited a normal profile of inflammatory cells. Moreover, Mmp9(-/-) periosteal grafts healed via intramembranous ossification in wild type hosts, but healed via endochondral ossification in Mmp9(-/-) hosts. We observed that macrophages accumulated at the periosteal surface in Mmp9(-/-) mice, suggesting that cell differentiation in the periosteum is influenced by factors such as BMP2 that are produced locally by inflammatory cells. Taken together, these results show that MMP9 mediates indirect effects on skeletal cell differentiation by regulating the inflammatory response and the distribution of inflammatory cells, leading to the local regulation of periosteal cell differentiation.

Expression of pleiotrophin, an important regulator of cell migration, is inhibited in intestinal epithelial cells by treatment with non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs for the suppression of inflammation and pain. However, the analgesic properties of NSAIDs are also associated with significant negative side effects, most notably in the gastrointestinal (GI) tract. Increasingly, evidence indicates that the ulcerogenic properties of some NSAIDs are not exclusively the result of inhibition of cyclooxygenase isoforms in the GI tract, and other mechanisms, including inhibition of cell migration and epithelial restitution, are being explored. Recently, microarray analysis was used to identify potential novel targets of NSAID activity in intestinal epithelial cells. Treated cells exhibited significant reductions in the gene expression of pleiotrophin (PTN), a cytokine and growth factor known to participate in angiogenesis and bone growth. This report aimed to confirm the microarray results reported previously, and to measure protein expression of PTN in intestinal epithelial cells. Furthermore, we also examined the effects of exogenous PTN on cell migration in the presence and absence of either NSAIDs with variable ulcerogenic potential or PTN-specific siRNA. Our results demonstrated that indomethacin and NS-398, two NSAIDs with ulcerogenic potential significantly decrease both gene and protein expressions of PTN in IEC-6 cells and protein expression in IEC-6-Cdx2 cells. Additionally, cell migration experiments with PTN siRNA showed that PTN is an important mediator of IEC-6 cell migration, and addition of exogenous PTN partially restores the deficits in cell migration caused by treatment with indomethacin and NS-398. Finally, measurement of PTN protein expression in the GI tract of horses treated with phenylbutazone showed that PTN expression is reduced by NSAIDs in vivo. Our results show that PTN is an important mediator of cell migration in IEC-6 cells, and PTN is a potential target through which NSAIDs may inhibit cell migration, epithelial restitution, and wound healing in the GI tract.

Bioavailability and pharmacokinetics of oral meloxicam in llamas

Background

South American camelids in the United States have rapidly developed into an important agricultural industry in need of veterinary services. Pain management is challenging in camelids because there are no drugs currently approved by the U.S. Food and Drug Administration for use in these species. Dosage regimens used for many therapeutic drugs have been extrapolated from other ruminants; however, the pharmacokinetics, in camelids, may differ from those of other species. Studies investigating the pharmacokinetics of cyclooxygenase-2 (COX-2) selective non-steroidal anti-inflammatory drugs in camelids are deficient in the published literature. Six adult llamas (121- 168 kg) were administered either a 1 mg/kg dose of oral or a 0.5 mg/kg dose of IV meloxicam in a randomized cross-over design with an 11 day washout period between treatments. Plasma samples collected up to 96 hours post-administration were analyzed by high pressure liquid chromatography and mass spectrometry detection (HPLC-MS) followed by non-compartmental pharmacokinetic analysis.

Results

A mean peak plasma concentration (C_MAX) of 1.314 μg/mL (Range: 0.826 – 1.776 μg/mL) was recorded at 21.4 hours (Range: 12.0 – 24.0 hours) with a half-life (T ½ λ_z) of 22.7 hours (Range: 18.0 – 30.8 hours) after oral meloxicam administration. In comparison, a half-life (T ½ λ_z) of 17.4 hours (Range: 16.2 – 20.7 hours) was demonstrated with IV meloxicam administration. The oral bioavailability (F) of meloxicam (dose normalized) was 76% (Range: 48 – 92%). No adverse effects associated with either treatment modality were observed in the llamas.

Conclusions

The mean bioavailability (F) of oral meloxicam was 76% indicating a high degree of gastrointestinal absorption. Plasma meloxicam concentrations >0.2 μg/mL were maintained for up to 72 h after oral administration; >0.2 μg/mL is considered to be the concentration of meloxicam required for analgesic effects in other species such as the horse. These data suggest that a single dosage of oral meloxicam at 1 mg/kg could potentially maintain therapeutic concentrations in plasma for up to 3 days in adult llamas.

Use of urinary biomarkers of renal ischemia in a lamb preclinical left ventricular assist device model

Evaluation of thrombogenicity is a critical component in the preclinical testing and development of blood pumps. Left ventricular assist devices (LVADs), because of their device routing, can produce thromboembolic showers to the kidney resulting in renal cortical ischemia or infarctions. Although postmortem evaluation of renal pathology can confirm ischemic events and infarctions, there are no validated and highly sensitive real-time measures of renal ischemia in the preclinical models. In this article, we report the evaluation of urinary biomarkers of ischemic tubular damage in a lamb preclinical LVAD model. We found that urinary excretion of glutathione-S-transferase-π, heat shock protein 1B, and hepatitis A virus cellular receptor 1 homologue precursor (HAVCR1/kidney injury molecule 1) were upregulated in toxic ischemic renal injury as well as in the immediate postoperative period in an LVAD-implanted lamb. These markers were consistent with both gross and histologic pathology, and proved far more sensitive for renal injury than serum blood urea nitrogen or creatinine concentrations.

Ocular penetration and anti-inflammatory activity of ketorolac 0.45% and bromfenac 0.09% against lipopolysaccharide-induced inflammation

PURPOSE

Anti-inflammatory activity of topical nonsteroidal anti-inflammatory drugs is mediated by suppression of cyclooxygenase (COX) isoenzymes. This study compared ocular penetration and inflammation suppression of topical ketorolac 0.45% and bromfenac 0.09% ophthalmic solutions in a rabbit model.

METHODS

At hour 0, 36 rabbits received ketorolac 0.45%, bromfenac 0.09%, or an artificial tear 3 times once every 20 min. Half of the rabbits in each group then received intravenous injections of lipopolysaccharide (LPS) and fluorescein isothiocyanate (FITC)-dextran at hour 1, and the other half at hour 10. Aqueous and iris-ciliary body (ICB) samples were collected in the former group at hour 2 (peak) and in the latter group at hour 11 (trough) An additional group of 6 animals received only FITC-dextran, and samples were collected 1 h later. Peak and trough nonsteroidal anti-inflammatory drug concentrations were compared with previously determined half-maximal inhibitory concentrations (IC(50)) for COX isoenzymes.

RESULTS

Peak and trough aqueous and ICB concentrations of ketorolac were at least 7-fold or greater than those of bromfenac. At peak levels, both ketorolac 0.45% and bromfenac 0.09% significantly inhibited LPS-induced aqueous prostaglandin E(2) and FITC-dextran elevation (P < 0.01). At trough, both study drugs significantly inhibited LPS-induced aqueous prostaglandin E(2) elevation (P < 0.05), but only ketorolac 0.45% significantly reduced LPS-induced aqueous FITC-dextran elevation (P < 0.01). Aqueous and ICB ketorolac concentrations exceeded its IC(50) for COX-1 and COX-2 at peak and trough. Aqueous and ICB bromfenac levels exceeded its IC(50) for COX-2 at peak and trough, but not for COX-1 at trough aqueous levels and peak and trough ICB levels.

CONCLUSIONS

Both ketorolac 0.45% and bromfenac 0.09% effectively suppressed inflammation at peak. At trough, only ketorolac 0.45% effectively suppressed inflammation as measured by FITC-dextran leakage. The difference in inflammation suppression may be due to differences in tissue concentrations and/or greater COX-1 suppression by ketorolac 0.45%.

Ontogeny of pulmonary cyclooxygenase-1 (COX-1) and -2 (COX-2)

Prostaglandins synthesized by enzymatic reactions such as cyclooxygenases have been implicated in lung pathophysiology. The goal of this study was to delineate the pulmonary ontogeny of cyclooxygenase enzymes (COX-1 and COX-2) immunohistochemical expression and cellular localization in various microanatomic locations of lungs from pre-term, term, and post-natal lambs. Lung tissues were obtained at 115 and 130 days of gestation from pre-term lambs, 145 days (term; complete gestation), and 15 days post-natally. No significant differences were seen in lung COX-1 expression at various microanatomic locations during pre-term, term, or postnatally. Moderate to strong COX-1 expression was present in macrophages, alveolar septa, bronchial smooth muscle cells, bronchiolar smooth muscle cells, vascular endothelial cells, and vascular smooth muscle cells. Minimal COX-1 expression was present in bronchial and bronchiolar epithelial cells. Most microanatomic locations lacked COX-2 expression with the exception of weak expression that was present in bronchial and bronchiolar epithelial cells at 145 days of full gestation and 15 days post-natally. This work suggests that: (a) COX-1 is constitutively expressed in lungs from pre-term, term, and post-natal lambs in various microanatomic pulmonary locations, (b) there is differential expression of COX-1 and COX-2 in the developing lung, and (c) COX-2 does not appear to play a role in lung fetal development, at least in neonatal lambs.

Cyclooxygenase-2 expression and its association with thyroid lesions

Cyclooxygenase (COX), also known as prostaglandin H synthase, catalyses the formation of prostaglandins from arachidonic acid. It can be expressed in response to various stimuli, such as hormones, mitogens, cytokines, other inflammatory mediators and growth factors. The product of COX-2 activity has been implicated in carcinogenesis by promoting angiogenesis, inhibiting apoptosis, increasing cell invasion and stimulating cell proliferation. It has also been proved that the regular intake of non-steroidal anti-inflammatory drugs (NSAIDs) decreases the risk of developing colon and breast cancers. Thus, it speaks for an important role of COX-2 in growth processes of various types of neoplasms. The connection between COX-2 activity and carcinogenesis has also been examined in human thyroid neoplasms. COX-2 overexpression has been reported in thyroid cancers and also in inflammatory conditions. In consequence there is significant interest whether COX-2 could be of importance as a molecular marker of malignancy in the case of thyroid carcinoma.

ISFM and AAFP Consensus Guidelines: Long-Term use of NSAIDs in Cats

NSAIDs and cats Non-steroidal anti-inflammatory drugs (NSAIDs) are an important class of drug in feline medicine, having analgesic, anti-inflammatory and antipyretic activity. While most published data on their use in this species relate to short-term (often perioperative) therapy, there is increasing evidence of the value of these drugs in treating chronic pain in cats (for example, that associated with degenerative joint disease), and some NSAIDs have now become licensed for long-term use in cats in some geographies. Most of our knowledge of therapeutic mechanisms or adverse drug reactions associated with NSAIDs is extrapolated from work in other species, and there is a paucity of published data relating to cats.

Guidelines These guidelines have been drawn together by an expert panel, which have reviewed the current literature on long-term NSAID use in cats and other species, and developed guidance on their use based on this information. The aim is to provide practical information for veterinarians to encourage appropriate NSAID therapy whenever cats will benefit from the use of these drugs.

Pathophysiology of cyclooxygenases in cardiovascular homeostasis

Cyclooxygenase (COX) catalyzes the conversion of arachidonic acid into prostaglandin H(2) (PGH(2)), which is subsequently converted to the prostanoids PGE(2), PGI(2), PGF(2alpha), and thromboxane A(2). COX has 2 distinct membrane-anchored isoenzymes: COX-1 and COX-2. COX-1 is constitutively expressed in most normal tissues; COX-2 is highly induced by proinflammatory mediators in the setting of inflammation, injury, and pain. Inhibitors of COX activity include conventional nonselective nonsteroidal anti-inflammatory drugs and selective nonsteroidal anti-inflammatory drugs, such as COX-2 inhibitors. The adverse effects of COX inhibitors on the cardiovascular system have been addressed in the last few years. In general, COX inhibitors have many effects, but those most important to the cardiovascular system can be direct (through the effects of prostanoids) and indirect (through alterations in fluid dynamics). Despite reports of detrimental human cardiovascular events associated with COX inhibitors, short, long, and lifetime preclinical toxicology studies in rodents and nonrodents have failed to identify these risks. This article focuses on the expression and function of COX enzymes in normal and pathologic conditions of the cardiovascular system and discusses the cardiovascular pathophysiologic complications associated with COX inhibition.

Pulmonary cyclooxygenase-1 (COX-1) and COX-2 cellular expression and distribution after respiratory syncytial virus and parainfluenza virus infection

Prostaglandins (PGs) play an important role in pulmonary physiology and various pathophysiological processes following infection. The initial step in the biosynthesis of PGs is regulated by two distinct cyclooxygenase enzymes, cyclooxygenase-1 (COX-1) and COX-2. The goal of this study was to investigate the pulmonary cellular localization and distribution of COX-1 and COX-2 in a neonatal lamb model following respiratory syncytial virus (RSV) and parainfluenza virus 3 (PI3) infection, organisms that also cause significant respiratory disease in children. No significant differences were seen in pulmonary COX-1 expression at various microanatomical locations following RSV or PI3 infection compared to controls. In contrast, COX-2 was upregulated following RSV and PI3 infection. Strong expression was restricted to bronchial and bronchiolar epithelial cells and macrophages, while minimal expression was present in the same microanatomical locations in the uninfected lungs. Other microanatomical locations in both the controls and the infected lungs lacked expression. This work suggests that during RSV or PI3 infection: (1) COX-1 cellular expression is not altered, (2) COX-2 cellular expression is upregulated in airway bronchiolar and bronchial epithelial cells and macrophages, (3) respiratory epithelium along with macrophages are important microanatomical compartments regulating the host inflammatory response during viral infection, and (4) COX-2 may be a potential target for RSV and PI3 therapy.

Macrophages protect against muscle atrophy and promote muscle recovery in vivo and in vitro: a mechanism partly dependent on the insulin-like growth factor-1 signaling molecule

Hindlimb unloading and reloading are characterized by a major loss of muscle force and are associated with classic leukocyte infiltration during recovery from muscle atrophy. Macrophages act as a cellular cornerstone by playing both pro- and anti-inflammatory roles during muscle recovery from atrophy. In the present study, we investigated the role of macrophages in muscle atrophy and regrowth using in vivo and in vitro models. Mice depleted in monocytes/macrophages and submitted to a hindlimb unloading and reloading protocol experienced a significant delay in muscle force recovery compared with matched placebo mice at 7 and 14 days after reloading. Furthermore, an in vitro myotube/macrophage coculture showed that anti-inflammatory macrophages, which contain apoptotic neutrophils and express low levels of cyclooxygenase-2, completely prevented the loss of protein content and the myotube atrophy observed after 2 days in low serum medium. The presence of macrophages also protected against the decrease in myosin heavy chain content in myotubes exposed to low serum medium for 1 day. Interestingly, the addition of an anti-IGF-1 antibody to the coculture significantly decreased the ability of macrophages to protect against myotube atrophy and myosin heavy chain loss after 2 days in low serum medium. These results clearly indicate that macrophages and, more precisely, the release of IGF-1 by macrophages, play an important role in recovery from muscle atrophy.

Species Comparison of the Role of p38 MAP Kinase in the Female Reproductive System

The p38 mitogen-activated protein kinases (MAPKs) are members of discrete signal transduction pathways that have significant regulatory roles in a variety of biological processes, depending on the cell, tissue and organ type. p38 MAPKs are involved in inflammation, cell growth and differentiation and cell cycle. In the female reproductive system, p38 MAPKs are known to regulate various aspects of the reproductive process such as mammalian estrous and menstrual cycles as well as early pregnancy and parturition. p38 MAPKs have also been implicated in alterations and pathologies observed in the female reproductive system. Therefore, pharmacologic modulation of p38 MAPKs, and inter-connected signaling pathways (e.g., estrogen receptor signaling, c-fos, c-jun), may influence reproductive physiology and function. This article provides a critical, comparative review of available data on the roles of p38 MAPKs in the mammalian female reproductive system and in reproductive pathophysiology in humans and preclinical species. We first introduce fundamental differences and similarities of the mammalian female reproductive system that should be considered by toxicologists and toxicologic pathologists when assessing the effects of new pharmacologic agents on the female reproductive system. We then explore in detail the known roles for p38 MAPKs and related molecules in female reproduction. This foundation is then extended to pathological conditions in which p38 MAPKs are thought to play an integral role.

TLR4-mediated Cox-2 expression increases intestinal ischemia/reperfusion-induced damage

Mesenteric IR induces significant inflammation and immune-mediated mucosal damage. TLR4 is a critical receptor in the induction of the inflammatory response and plays a role in intestinal homeostasis. To determine the role of TLR4 in IR-induced epithelial damage, we performed IR studies using TLR4(lps-def) and TLR4(lps-n) mice and analyzed mucosal damage and inflammation. We found that the absence of TLR4 or TLR4-induced signaling attenuated local mucosal damage with significantly decreased cytokine and eicosanoid secretion including PGE2 production. Similar results were seen in MyD88-/- mice. Wild-type mice treated with NS-398 (a Cox-2 inhibitor) not only decreased PGE2 production but also attenuated tissue damage. In contrast, PGE2 was not sufficient to induce damage in the TLR4(lps-def) mice. Together, these data indicate that TLR4 stimulation of Cox-2 activation of PGE2 production is necessary but not sufficient for intestinal IR-induced damage and inflammation.