Post-traumatic osteoarthritis progression is diminished by early mechanical unloading and anti-inflammatory treatment in mice.

OBJECTIVE: Post-traumatic osteoarthritis (PTOA) is a degenerative joint disease initiated by injury. Early phase (0-7 days) treatments often include rest (unloading) and anti-inflammatory medications, but how those early interventions impact PTOA progression is unknown. We hypothesized that early unloading and anti-inflammatory treatment would diminish joint inflammation and slow PTOA progression. DESIGN: Mice were injured with non-invasive ACL rupture followed by hindlimb unloading (HLU) or normal cage activity (ground control: GC) for 7 days, after which all mice were allowed normal cage activity. HLU and GC mice were treated with daily celecoxib (CXB; 10 mg/kg IP) or vehicle. Protease activity was evaluated using in vivo fluorescence imaging, osteophyte formation and epiphyseal trabecular bone were quantified using micro-computed tomography, and synovitis and articular cartilage were evaluated using whole-joint histology at 7, 14, 21, and 28 days post-injury. RESULTS: HLU significantly reduced protease activity (-22-30% compared to GC) and synovitis (-24-50% relative to GC) at day 7 post-injury (during unloading), but these differences were not maintained at later timepoints. Similarly, trabecular bone volume was partially preserved in HLU mice at during unloading (-14-15% BV/TV for HLU mice, -21-22% for GC mice relative to uninjured), but these differences were not maintained during reloading. Osteophyte volume was reduced by both HLU and CXB, but there was not an additive effect of these treatments (HLU: -46%, CXB: -30%, HLU + CXB: -35% relative to vehicle GC at day 28). CONCLUSIONS: These data suggest that early unloading following joint injury can reduce inflammation and potentially slow PTOA progression.

The effect of labour on the coagulation system in the term neonate.

The coagulation system of the foetus is markedly different from that of adults. To assess the influence of maternal age, mode of delivery and intrapartum events, and foetal gender and weight on the foetal coagulation system. Cord blood was collected from 154 healthy pregnant women, with gestational age 37 - 42 weeks at birth. Mann-Whitney test was used for analysis of binary data and continuous variables were analysed using Pearson's correlation coefficient. Mean cord blood levels of FVIII:C, VWF:Ag, VWF:CB, FIX, FXI, FXII and plasminogen were significantly higher in babies delivered after labour, compared to those delivered after an elective caesarean. Mean cord blood levels of FII (P = 0.003), FV (P = 0.009), FVII (P = 0.0004) and FX (P = 0.0009) were significantly lower in the babies with meconium stained liquor in labour, compared with those with clear liquor. Augmentation with oxytocin, instrumental delivery, did not affect any of the factor levels and duration of labour did not have an effect on the level of coagulation proteins in cord blood. This study provides valuable information about effect of labour on the coagulation system of the foetus. It is concluded that, in cord blood, the results of coagulation parameters in the newborn baby should be considered in light of mode of delivery and events of labour.

Exploratory Multisite MR Spectroscopic Imaging Shows White Matter Neuroaxonal Loss Associated with Complications of Type 1 Diabetes in Children.

BACKGROUND AND PURPOSE: Type 1 diabetes affects over 200,000 children in the United States and is associated with an increased risk of cognitive dysfunction. Prior single-site, single-voxel MRS case reports and studies have identified associations between reduced NAA/Cr, a marker of neuroaxonal loss, and type 1 diabetes. However, NAA/Cr differences among children with various disease complications or across different brain tissues remain unclear. To better understand this phenomenon and the role of MRS in characterizing it, we conducted a multisite pilot study. MATERIALS AND METHODS: In 25 children, 6-14 years of age, with type 1 diabetes across 3 sites, we acquired T1WI and axial 2D MRSI along with phantom studies to calibrate scanner effects. We quantified tissue-weighted NAA/Cr in WM and deep GM and modeled them against study covariates. RESULTS: We found that MRSI differentiated WM and deep GM by NAA/Cr on the individual level. On the population level, we found significant negative associations of WM NAA/Cr with chronic hyperglycemia quantified by hemoglobin A1c (P < .005) and a history of diabetic ketoacidosis at disease onset (P < .05). We found a statistical interaction (P < .05) between A1c and ketoacidosis, suggesting that neuroaxonal loss from ketoacidosis may outweigh that from poor glucose control. These associations were not present in deep GM. CONCLUSIONS: Our pilot study suggests that MRSI differentiates GM and WM by NAA/Cr in this population, disease complications may lead to neuroaxonal loss in WM in children, and deeper investigation is warranted to further untangle how diabetic ketoacidosis and chronic hyperglycemia affect brain health and cognition in type 1 diabetes.

Musculoskeletal changes following non-invasive knee injury using a novel mouse model of post-traumatic osteoarthritis.

OBJECTIVE: Post-traumatic osteoarthritis (PTOA) is a common consequence of traumatic joint injury, with 50% of anterior cruciate ligament (ACL) rupture patients developing PTOA within 10-20 years. Currently accepted mouse models of PTOA initiate symptoms using various methods, none of which faithfully mimic clinically-relevant injury conditions. In this study we characterize a novel non-invasive mouse model of PTOA that injures the ACL with a single load of tibial compression overload. We utilize this model to determine the time course of articular cartilage and subchondral bone changes following knee injury. DESIGN: Mice were euthanized 1, 3, 7, 14, 28, or 56 days after non-invasive knee injury. Knees were scanned using micro-computed tomography (µCT) in order to quantify subchondral trabecular bone, subchondral bone plate, and non-native bone formation (heterotopic ossification). Development of osteoarthritis (OA) was graded using the osteoarthritis research society international (OARSI) scale on histological sections of injured and uninjured knees. RESULTS: Following injury we observed a rapid loss of trabecular bone in injured knees compared to uninjured knees by 7 days post-injury, followed by a partial recovery of trabecular bone to a new steady state by 28 days post-injury. We also observed considerable non-native bone formation by 56 days post-injury. Grading of histological sections revealed deterioration of articular cartilage by 56 days post-injury, consistent with development of mild OA. CONCLUSIONS: This study establishes a novel mouse model of PTOA, and describes the time course of musculoskeletal changes following knee injury, helping to establish the window of opportunity for preventative treatment.

First 20 years with recombinant FVIIa (NovoSeven).

This review describes the background for the development of recombinant FVIIa (rFVIIa; NovoSeven) for use in haemophilic patients with inhibitors. The first proof of principle for using pharmacological doses of FVIIa as a haemostatic agent was obtained by producing small amounts of pure plasma-derived FVIIa, which showed encouraging effect in two patients with haemophilia A and inhibitors. To make pure FVIIa available for use in a larger number of patients, rFVIIa was produced that was approved for use in patients with inhibitors against coagulation factors (congenital haemophilia and acquired haemophilia) in 1996 (EU), 1999 (USA) and 2000 (Japan). The efficacy rate in severe bleedings and in major surgery including major orthopaedic surgery has been found to be around 90% in controlled studies, and no serious safety concerns have been demonstrated. The availability of rFVIIa has facilitated the performance of elective major surgery in haemophilia patients with inhibitors. Further steps along the vision of providing a treatment for inhibitor patients similar to non-inhibitor patients have been the efficacy of rFVIIa in home-treatment and recently the encouraging experience in prophylaxis. The concept of using pharmacological doses of rFVIIa as a haemostatic agent is a new one, which has caused difficulties in finding the correct dose. A step forward has been the demonstration that similar efficacy can be achieved after one single dose of 270 µg kg(-1) instead of three injections of a dose of 90 µg kg(-1). The higher clearance rate in children suggests that higher doses may be beneficial in children. The availability of rFVIIa has made advances in the understanding of coagulation processes possible. In a cell-based in vitro model, it has been shown that rFVIIa binds to preactivated platelets if present in concentrations of 30 nm or higher. By doing so, it activates FX into FXa and enhances the thrombin generation on the activated platelet surface in the absence of FVIII/FIX. Through the increased thrombin generation, a firm, well-structured fibrin haemostatic plug, which is resistant to premature lysis, is formed. By exploiting this mechanism of action, rFVIIa may also be effective in situations other than haemophilia, characterized by an impaired thrombin generation.

The risk of variant Creutzfeldt-Jakob disease among UK patients with bleeding disorders, known to have received potentially contaminated plasma products.

The risk of variant Creutzfeldt-Jakob disease (vCJD) from potentially infected plasma products remains unquantified. This risk has been assessed for 787 UK patients with an inherited bleeding disorder prospectively followed-up for 10-20 years through the UK Haemophilia Centre Doctors' Organisation (UKHCDO) Surveillance Study. These patients had been treated with any of 25 'implicated' clotting factor batches from 1987 to 1999, which included in their manufacture, plasma from eight donors who subsequently developed clinical vCJD. Variant CJD infectivity of these batches was estimated using plasma fraction infectivity estimates and batch-manufacturing data. Total potential vCJD infectivity received by each patient has been estimated by cumulating estimated infectivity from all doses received during their lifetime. Of 787 patients, 604 (77%) were followed-up for over 13 years following exposure to an implicated batch. For these 604 patients, the estimated vCJD risk is ≥ 1% for 595, ≥ 50% for 164 and 100% for 51. This is additional to background UK population risk due to dietary exposure. Of 604 patients, 94 (16%) received implicated batches linked to donors who developed clinical vCJD within 6 months of their donations. One hundred and fifty-one (25%) had received their first dose when under 10 years of age. By 1st January 2009, none of these patients had developed clinical vCJD. The absence of clinical vCJD cases in this cohort to date suggests that either plasma fraction infectivity estimates are overly precautionary, or the incubation period is longer for this cohort than for implicated cellular blood product recipients. Further follow-up of this cohort is needed.

Joint protection in haemophilia.

Haemarthroses (intra-articular haemorrhages) are a frequent finding typically observed in patients with haemophilia. Diagnosis and treatment of these bleeding episodes must be delivered as early as possible. Additionally, treatment should ideally be administered intensively (enhanced on-demand treatment) until the resolution of symptoms. Joint aspiration plays an important role in acute and profuse haemarthroses as the presence of blood in the joint leads to chondrocyte apoptosis and chronic synovitis, which will eventually result in joint degeneration (haemophilic arthropathy). Ultrasonography (US) is an appropriate diagnostic technique to assess the evolution of acute haemarthrosis in haemophilia, although magnetic resonance imaging remains the gold standard as far as imaging techniques are concerned. Some patients experience subclinical haemarthroses, which eventually tend to result in some degree of arthropathy, especially in the ankles. Nowadays, the most effective way of protecting these patients is primary prophylaxis, which in practice changes severe haemophilia into moderate haemophilia, preventing or at least minimizing the occurrence of haemarthrosis. If primary prophylaxis is, for whatever reason not an option, secondary prophylaxis and enhanced on demand treatment should be considered. Two alternatives are available for inhibitor patients: (i) control of haemostasis using by-passing agents (rFVIIa or aPCCs) either as enhanced on demand treatment or secondary prophylaxis, as appropriate, following the same basic principles used for non-inhibitor patients and (ii) immune tolerance induction (ITI) to eradicate the inhibitor.

Risk reduction strategies for variant Creutzfeldt-Jakob disease transmission by UK plasma products and their impact on patients with inherited bleeding disorders.

SUMMARY: The appearance and rapid evolution of BSE in UK cattle in the mid 1980s, with compelling data supporting variant Creutzfeldt-Jakob disease (vCJD) as its human manifestation, pose a potentially severe threat to public health. Three clinical cases and one asymptomatic case of vCJD infection have been reported in UK recipients of non-leucodepleted red cell transfusions from donors subsequently diagnosed with vCJD. Plasma from both these and other donors who later developed vCJD has contributed towards plasma pools used to manufacture clotting factor concentrate. The United Kingdom Haemophilia Centre Doctors' Organisation (UKHCDO) Surveillance Study has detected asymptomatic vCJD postmortem in a haemophilic patient treated with UK plasma products including two batches of clotting factor linked to a donor who subsequently developed vCJD. Over 4000 bleeding disorder patients treated with UK plasma products are recorded on the UKHCDO National Haemophilia Database. The risk of vCJD transmission by plasma products is not known. However, public health precautions have been implemented since 2004 in all UK inherited bleeding disorder patients who received UK-sourced plasma products between 1980 and 2001 to minimize the possible risk of onward vCJD transmission. We evaluate vCJD surveillance and risk management measures taken for UK inherited bleeding disorder patients, report current data and discuss resultant challenges and future directions.

Emergence of functional neuromuscular junctions in an engineered, multicellular spinal cord-muscle bioactuator.

Three-dimensional (3D) biomimetic systems hold great promise for the study of biological systems in vitro as well as for the development and testing of pharmaceuticals. Here, we test the hypothesis that an intact segment of lumbar rat spinal cord will form functional neuromuscular junctions (NMJs) with engineered, 3D muscle tissue, mimicking the partial development of the peripheral nervous system (PNS). Muscle tissues are grown on a 3D-printed polyethylene glycol (PEG) skeleton where deflection of the backbone due to muscle contraction causes the displacement of the pillar-like "feet." We show that spinal cord explants extend a robust and complex arbor of motor neurons and glia in vitro. We then engineered a "spinobot" by innervating the muscle tissue with an intact segment of lumbar spinal cord that houses the hindlimb locomotor central pattern generator (CPG). Within 7 days of the spinal cord being introduced to the muscle tissue, functional neuromuscular junctions (NMJs) are formed, resulting in the development of an early PNS in vitro. The newly innervated muscles exhibit spontaneous contractions as measured by the displacement of pillars on the PEG skeleton. Upon chemical excitation, the spinal cord-muscle system initiated muscular twitches with a consistent frequency pattern. These sequences of contraction/relaxation suggest the action of a spinal CPG. Chemical inhibition with a blocker of neuronal glutamate receptors effectively blocked contractions. Overall, these data demonstrate that a rat spinal cord is capable of forming functional neuromuscular junctions ex vivo with an engineered muscle tissue at an ontogenetically similar timescale.

Current approaches in haemophilic arthropathy of the hip.

The hip is considered to be one of the main load bearing joints of the body. In the haemophilic patient joint bleeds can be catastrophic, leading to long-term joint degeneration and accompanying arthritis. In this review we explore the mechanisms of joint destruction, with particular consideration of the anatomy of the hip and how it may influence disease progression. We also review current strategies for treatment including hip replacement in the haemophilic patient and describe our experiences as a unit. Finally we evaluate future prospects in the management of hip disease in haemophilia.

Ankle arthropathy in the haemophilic patient: a description of a novel ankle arthrodesis technique.

The ankle joint is well known to show early involvement in severe haemophilia. We describe a novel operative technique developed by the senior author. This combines a medial approach to the ankle, medial malleolar osteotomy, bone graft and compression with staples. All patients had excellent pain relief and improvement in function with 100% achieving bony union. There was a significant improvement in Mazur ankle scores following ankle fusion (P < 0.01). This surgical technique gives good results which are reproducible in this patient population.

Characterization of a Multiple-Scan-Rate Voltammetric Waveform for Real-Time Detection of Met-Enkephalin.

Opioid peptides are critically involved in a variety of physiological functions necessary for adaptation and survival, and as such, understanding the precise actions of endogenous opioid peptides will aid in identification of potential therapeutic strategies to treat a variety of disorders. However, few analytical tools are currently available that offer both the sensitivity and spatial resolution required to monitor peptidergic concentration fluctuations in situ on a time scale commensurate with that of neuronal communication. Our group has developed a multiple-scan-rate waveform to enable real-time voltammetric detection of tyrosine containing neuropeptides. Herein, we have evaluated the waveform parameters to increase sensitivity to methionine-enkephalin (M-ENK), an endogenous opioid neuropeptide implicated in pain, stress, and reward circuits. M-ENK dynamics were monitored in adrenal gland tissue, as well as in the dorsal striatum of anesthetized and freely behaving animals. The data reveal cofluctuations of catecholamine and M-ENK in both locations and provide measurements of M-ENK dynamics in the brain with subsecond temporal resolution. Importantly, this work also demonstrates how voltammetric waveforms can be customized to enhance detection of specific target analytes, broadly speaking.

Defective insulin signaling pathway and increased glycogen synthase kinase-3 activity in the brain of diabetic mice: parallels with Alzheimer's disease and correction by insulin.

We have evaluated the effect of peripheral insulin deficiency on brain insulin pathway activity in a mouse model of type 1 diabetes, the parallels with Alzheimer's disease (AD), and the effect of treatment with insulin. Nine weeks of insulin-deficient diabetes significantly impaired the learning capacity of mice, significantly reduced insulin-degrading enzyme protein expression, and significantly reduced phosphorylation of the insulin-receptor and AKT. Phosphorylation of glycogen synthase kinase-3 (GSK3) was also significantly decreased, indicating increased GSK3 activity. This evidence of reduced insulin signaling was associated with a concomitant increase in tau phosphorylation and amyloid beta protein levels. Changes in phosphorylation levels of insulin receptor, GSK3, and tau were not observed in the brain of db/db mice, a model of type 2 diabetes, after a similar duration (8 weeks) of diabetes. Treatment with insulin from onset of diabetes partially restored the phosphorylation of insulin receptor and of GSK3, partially reduced the level of phosphorylated tau in the brain, and partially improved learning ability in insulin-deficient diabetic mice. Our data indicate that mice with systemic insulin deficiency display evidence of reduced insulin signaling pathway activity in the brain that is associated with biochemical and behavioral features of AD and that it can be corrected by insulin treatment.

Prevention of arthropathy in haemophilia - intensive on-demand treatment, UK perspective.

In the past, there were only minimal studies aimed at establishing the dose of concentrate required for treating an acute joint bleed in patients without inhibitors. The cost of treatment with bypassing agents consumes huge economic resources and therefore it is important to have rigorous studies to establish rational dosing. Both the FEIBA NovoSeven Comparative study and the comparative dosing study have been bold attempts to clarify treatment regimens for managing joint bleeds in patients with inhibitors. As a very challenging situation in which to conduct research, it is important that such endeavour continues.

Carrier testing in haemophilia A and B: adult carriers' and their partners' experiences and their views on the testing of young females.

This is a descriptive study, which aims to report adult carriers' and their husbands/partners' experiences of carrier diagnosis and their views as to how these issues should be handled for the next generation. Following an initial pilot, 105 carriers and husbands/partners responded to a postal questionnaire. Most of the adult carriers had been tested because either they or their parents wanted to know their carrier status or they had a son diagnosed with haemophilia. The respondents agreed that the main reasons for testing young potential carriers should be either a family history of severe haemophilia or that the young person or her parents wanted to know her status. Forty per cent (35/87) believed the earliest age for carrier testing should be 0-9 years, 44% (38/87) 10-15 years and 16% (14/87) > or =16 years. Respondents aged 18-39 years were more likely to be in favour of testing <2 years. If parents and teenagers disagreed, the majority of parents thought that a test should not be forced, consent refused or results withheld. Genetic counselling provides an important opportunity for parents, who want a very early genetic test, to explore their motivations and balance their desire to prepare and protect their daughter with her right to decide as a teenager.

Pregnancy in carriers of haemophilia.

The aim of the study was to review the complications, management and outcome of pregnancy in carriers of haemophilia over a 10-year period following the introduction of a multidisciplinary management guideline. Comparison was made to a 10-year cohort prior to implementation of the guidelines. A retrospective review of case notes of carriers of haemophilia (41 haemophilia A, 12 haemophilia B) who had received obstetric care at the Royal Free Hospital between 1995 and 2005 was conducted. There were 90 pregnancies (65 live births, 13 miscarriages, 12 terminations). Prenatal testing was taken up in 97% (63/65) of pregnancies where the mother was known to be a carrier of haemophilia. The majority (71%; 46/65) chose only to have non-invasive fetal sex determination. Seventeen (26%) had invasive testing (13 primarily for haemophilia and four primarily for chromosomal abnormalities). Termination of pregnancy was opted for in 67% (6/9) of pregnancies affected with haemophilia. Pregnancy was accompanied by a marked rise in factor VIII levels compared to only a small rise in factor IX levels. Invasive intrapartum monitoring techniques and instrumental deliveries were avoided in all pregnancies known to be at risk of haemophilia. Regional block was performed in 25 pregnancies for labour/delivery with no complications. The caesarean section rate was 47%. The incidence of primary and secondary postpartum haemorrhage was 19% and 2%, respectively. There were two neonatal head bleeding complications associated with prolonged labour or instrumental delivery. Availability of management guideline and care provided in a multidisciplinary approach can help to minimize bleeding complications in carriers of haemophilia and their newborns.

Recombinant factor VIIa to prevent surgical bleeding in factor XI deficiency.

Factor XI (FXI) deficiency is associated with bleeding after invasive procedures. Risks of human plasma-derived FXI replacement products include transfusion transmitted infection, thrombosis and fluid overload. This study was designed to test the hypothesis that recombinant factor VIIa (rFVIIa) is an effective haemostatic agent in patients with FXI deficiency undergoing surgery. Fourteen FXI deficient patients [five severely deficient (FXI:C <20 U dL(-1)) and nine partially deficient (FXI:C 20-70 U dL(-1)] received rFVIIa to prevent surgical bleeding during five major, four minor and six dental procedures. Minor surgical and dental procedures were covered with two doses of rFVIIa (90 microg kg(-1) i.v.), the first pre-operatively and the second 4 h postoperatively. Major surgery was covered with 90 microg kg(-1) i.v. two hourly for the first 24 h and four hourly for the second 24 h. Oral tranexamic acid was given for 7 days postoperatively. Effective haemostasis was observed in all cases and no alternative haemostatic agents or blood transfusions were required. Three adverse events were recorded; an acute cerebrovascular accident in a patient with a history of cardiovascular disease, an allergic reaction and local phlebitis. In this study, rFVIIa was an effective alternative to plasma-derived FXI replacement for the prevention of surgical bleeding in FXI deficient patients but rFVIIa may not be suitable for patients with pre-existing risk factors for thrombosis.

Prevention of haemophilic arthropathy during childhood. May common orthopaedic management be extrapolated from patients without inhibitors to patients with inhibitors?

We recommend prophylaxis in haemophilic children with an inhibitor as a way of preventing the musculoskeletal impairment that is likely to affect them. This approach has been used for children without inhibitors with excellent results. If prophylaxis is not feasible, we suggest that intensive on-demand treatment should be given. Two agents, recombinant activated FVII (rFVIIa) and activated prothrombin complex concentrates (aPCC), are currently used to control haemostasis either for prophylaxis or intensive on-demand treatment. As it is recombinant, rFVIIa would seem more appropriate to be employed in children. aPCC could be used in adults, or in the event of an unsatisfactory response to rFVIIa. We recommend prophylaxis or, at least, intensive on-demand treatment in haemophilia children with inhibitors. Both rFVIIa and aPCC are being used for this purpose. It would seem that rFVIIa might be more appropriate for children as it is a recombinant product. Nevertheless, after skeletal maturity (in adults), both agents could be used indistinctively (taking into consideration that FEIBA is a plasma-derived product). We still need more well-designed comparative studies in order to be able to assert that our consensus-based conclusion is evidence based. In orthopaedic surgery, both aPCC and rFVIIa have been reported to be effective in controlling perioperative haemostasis, although in practice most centres have so far used rFVIIa for their orthopaedic procedures. We recommend rehabilitation programmes for all patients with inhibitors in order to mitigate the disabling and handicapping impact of their condition and thereby enable them to achieve social integration. Programmes for haemophilic children without inhibitors can be applied to children with inhibitors but should be individually tailored.

Menstrual problems in university students: an electronic mail survey.

OBJECTIVE: To establish the prevalence of menstrual-related problems among university students. MATERIALS AND METHODS: A questionnaire regarding gynecological, bleeding and family history was sent by electronic mail (e-mail) to all female students attending University College London (UCL). RESULTS: A total of 767 students aged 18-39 years replied; 71% had a regular menstrual cycle. One in three (n = 264) had received some treatment for their menstrual periods (such as the combined oral contraceptive pill or simple analgesia). Those with heavy or painful periods were more likely to feel that their menstrual problems had a substantial impact on their academic and social life; however, even among those with light periods, one in every four females felt that their life was considerably affected. CONCLUSION: A considerable prevalence of menstrual-related problems was demonstrated among this young healthy population. Additionally, the use of e-mail could present potential benefits as a research medium for this kind of study.

Allergic lung responses are increased in prostaglandin H synthase-deficient mice.

To investigate the function of prostaglandin H synthase-1 and synthase-2 (PGHS-1 and PGHS-2) in the normal lung and in allergic lung responses, we examined allergen-induced pulmonary inflammation and airway hyperresponsiveness in wild-type mice and in PGHS-1(-/-) and PGHS-2(-/-) mice. Among nonimmunized saline-exposed groups, we found no significant differences in lung function or histopathology, although PGE(2) was dramatically reduced in bronchoalveolar lavage (BAL) fluid from PGHS-1(-/-) mice, relative to wild-type or PGHS-2(-/-) mice. After ovalbumin sensitization and challenge, lung inflammatory indices (BAL cells, proteins, IgE, lung histopathology) were significantly greater in PGHS-1(-/-) mice compared with PGHS-2(-/-) mice, and both were far greater than in wild-type mice, as illustrated by the ratio of eosinophils in BAL fluid (8:5:1, respectively). Both allergic PGHS-1(-/-) and PGHS-2(-/-) mice exhibited decreased baseline respiratory system compliance, whereas only allergic PGHS-1(-/-) mice showed increased baseline resistance and responsiveness to methacholine. Ovalbumin exposure caused a modest increase in lung PGHS-2 protein and a corresponding increase in BAL fluid PGE(2) in wild-type mice. We conclude that (a) PGHS-1 is the predominant enzyme that biosynthesizes PGE(2) in the normal mouse lung; (b) PGHS-1 and PGHS-2 products limit allergic lung inflammation and IgE secretion and promote normal lung function; and (c) airway inflammation can be dissociated from the development of airway hyperresponsiveness in PGHS-2(-/-) mice.