Hypoxia-selective allosteric destabilization of activin receptor-like kinases: A potential therapeutic avenue for prophylaxis of heterotopic ossification.

Heterotopic ossification (HO), the pathological extraskeletal formation of bone, can arise from blast injuries, severe burns, orthopedic procedures and gain-of-function mutations in a component of the bone morphogenetic protein (BMP) signaling pathway, the ACVR1/ALK2 receptor serine-threonine (protein) kinase, causative of Fibrodysplasia Ossificans Progressiva (FOP). All three ALKs (-2, -3, -6) that play roles in bone morphogenesis contribute to trauma-induced HO, hence are well-validated pharmacological targets. That said, development of inhibitors, typically competitors of ATP binding, is inherently difficult due to the conserved nature of the active site of the 500+ human protein kinases. Since these enzymes are regulated via inherent plasticity, pharmacological chaperone-like drugs binding to another (allosteric) site could hypothetically modulate kinase conformation and activity. To test for such a mechanism, a surface pocket of ALK2 kinase formed largely by a key allosteric substructure was targeted by supercomputer docking of drug-like compounds from a virtual library. Subsequently, the effects of docked hits were further screened in vitro with purified recombinant kinase protein. A family of compounds with terminal hydrogen-bonding acceptor groups was identified that significantly destabilized the protein, inhibiting activity. Destabilization was pH-dependent, putatively mediated by ionization of a histidine within the allosteric substructure with decreasing pH. In vivo, nonnative proteins are degraded by proteolysis in the proteasome complex, or cellular trashcan, allowing for the emergence of therapeutics that inhibit through degradation of over-active proteins implicated in the pathology of diseases and disorders. Because HO is triggered by soft-tissue trauma and ensuing hypoxia, dependency of ALK destabilization on hypoxic pH imparts selective efficacy on the allosteric inhibitors, providing potential for safe prophylactic use.

Palovarotene inhibits connective tissue progenitor cell proliferation in a rat model of combat-related heterotopic ossification.

Heterotopic ossification (HO) develops in the extremities of wounded service members and is common in the setting of high-energy penetrating injuries and blast-related amputations. No safe and effective prophylaxis modality has been identified for this patient population. Palovarotene has been shown to reduce bone formation in traumatic and genetic models of HO. The purpose of this study was to determine the effects of Palovarotene on inflammation, progenitor cell proliferation, and gene expression following a blast-related amputation in a rodent model (n = 72 animals), as well as the ability of Raman spectroscopy to detect early HO before radiographic changes are present. Treatment with Palovarotene was found to dampen the systemic inflammatory response including the cytokines IL-6 (p = 0.01), TNF-α (p = 0.001), and IFN-γ (p = 0.03) as well as the local inflammatory response via a 76% reduction in the cellular infiltration at post-operative day (POD)-7 (p = 0.03). Palovarotene decreased osteogenic connective tissue progenitor (CTP-O) colonies by as much as 98% both in vitro (p = 0.04) and in vivo (p = 0.01). Palovarotene treated animals exhibited significantly decreased expression of osteo- and chondrogenic genes by POD-7, including BMP4 (p = 0.02). Finally, Raman spectroscopy was able to detect differences between the two groups by POD-1 (p < 0.001). These results indicate that Palovarotene inhibits traumatic HO formation through multiple inter-related mechanisms including anti-inflammatory, anti-proliferative, and gene expression modulation. Further, that Raman spectroscopy is able to detect markers of early HO formation before it becomes radiographically evident, which could facilitate earlier diagnosis and treatment. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1135-1144, 2018.

Early local delivery of vancomycin suppresses ectopic bone formation in a rat model of trauma-induced heterotopic ossification.

Heterotopic ossification (HO) is a debilitating sequela of high-energy injuries. It frequently requires surgical excision once symptomatic and there is no practical prophylaxis for combat-injured patients. In this study, we examined the effect of local vancomycin powder on HO formation in a small animal model of blast-related, post-traumatic HO. Male Sprague-Dawley rats were subjected to a polytraumatic extremity injury and amputation with or without methicillin-resistant Staphylococcus aureus infection. Animals were randomized to receive a single local application of vancomycin (20 mg/kg) at the time of injury (POD-0, n = 34) or on postoperative day-3 (POD-3, n = 11). Quantitative volumetric measurement of ectopic bone was calculated at 12-weeks post-injury by micro-CT. Bone marrow and muscle tissues were also collected to determine the bacterial burden. Blood for serum cytokine analysis was collected at baseline and post-injury. Vancomycin treatment on POD-0 suppressed HO formation by 86% and prevented bone marrow and soft tissue infections. We concurrently observed a marked reduction histologically in nonviable tissue, chronic inflammatory cell infiltrates, bone infection, fibrous tissue, and areas of bone necrosis within this same cohort. Delayed treatment was significantly less efficacious. Neither treatment had a marked effect on the production of pro-inflammatory cytokines. Our study demonstrates that local vancomycin treatment at the time of injury significantly reduces HO formation in both the presence and absence of infection, with decreased efficacy if not given early. These findings further support the concept that the therapeutic window for prophylaxis is narrow, highlighting the need to develop early treatment strategies for clinical management. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2397-2406, 2017.

SCISSOR-Spinal Cord Injury Study on Small molecule-derived Rho inhibition: a clinical study protocol.

INTRODUCTION: The approved analgesic and anti-inflammatory drugs ibuprofen and indometacin block the small GTPase RhoA, a key enzyme that impedes axonal sprouting after axonal damage. Inhibition of the Rho pathway in a central nervous system-effective manner requires higher dosages compared with orthodox cyclooxygenase-blocking effects. Preclinical studies on spinal cord injury (SCI) imply improved motor recovery after ibuprofen/indometacin-mediated Rho inhibition. This has been reassessed by a meta-analysis of the underlying experimental evidence, which indicates an overall effect size of 20.2% regarding motor outcome achieved after ibuprofen/indometacin treatment compared with vehicle controls. In addition, ibuprofen/indometacin may also limit sickness behaviour, non-neurogenic systemic inflammatory response syndrome (SIRS), neuropathic pain and heterotopic ossifications after SCI. Consequently, 'small molecule'-mediated Rho inhibition after acute SCI warrants clinical investigation. METHODS AND ANALYSIS: Protocol of an investigator-initiated clinical open-label pilot trial on high-dose ibuprofen treatment after acute traumatic, motor-complete SCI. A sample of n=12 patients will be enrolled in two cohorts treated with 2400 mg/day ibuprofen for 4 or 12 weeks, respectively. The primary safety end point is an occurrence of serious adverse events, primarily gastroduodenal bleedings. Secondary end points are pharmacokinetics, feasibility and preliminary effects on neurological recovery, neuropathic pain and heterotopic ossifications. The primary safety analysis is based on the incidence of severe gastrointestinal bleedings. Additional analyses will be mainly descriptive and casuistic. ETHICS AND DISSEMINATION: The clinical trial protocol was approved by the responsible German state Ethics Board, and the Federal Institute for Drugs and Medical Devices. The study complies with the Declaration of Helsinki, the principles of Good Clinical Practice and all further applicable regulations. This safety and pharmacokinetics trial informs the planning of a subsequent randomised controlled trial. Regardless of the result of the primary and secondary outcome assessments, the clinical trial will be reported as a publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT02096913; Pre-results.

Could heterotopic ossification be prevented by varying dietary n-3/n-6 polyunsaturated fatty acid ratio: a novel perspective to its treatment?

Heterotopic ossification (HO) is a common complication following with musculoskeletal trauma and surgical procedures. It usually decreases joint mobility and eventually causes loss of joint function. Despite nonsteroidal anti-inflammatory drugs (NSAIDs), the inhibitor of cyclooxygenase(COX), have been proven to prevent HO effectively via prostaglandin E2 synthesis regulation and modulation of tissue responsiveness to pro-inflammatory signaling, HO prevention is still a matter of debate for clinicians to avoid the side effect of NSAIDs. Interestingly, it is suggested that PGE2 production and pro-inflammatory microenvironment in body could be modified by varying the ratio of the precursor fatty acids in the diet. On account of the effect of dietary (n-6)/(n-3) PUFAs ratio on both COX metabolism and pro-inflammatory cytokines mediated biological responsiveness, we hypothesized lowering dietary (n-6)/(n-3) PUFAs ratio may not only directly reduce the substrate of COX-2 and COX-2 activity, but also partially ameliorate tissue inflammatory responsiveness to cytokines correlated with HO development,exerting an inhibitory effect on PGE2 synthesis to prevent HO formation. The negative role of lowering dietary (n-6)/(n-3) PUFAs ratio on angiogenesis, cytokines-induced apoptosis, inflammatory responsiveness and osteogenesis could also contribute to its action on HO development. If our hypothesis is proved to be corrected, it could be an innovative method to treat HO.

Periarticular infiltration in total hip replacement: effect on heterotopic ossification, analgesic requirements and outcome.

BACKGROUND: Up to 80% of patients develop heterotopic ossification (HO) following total hip replacement (THR) and high grades may adversely affect outcome. This study investigated the influence of local infiltration of a NSAID (Ketorolac) and local anaesthetic on the incidence and grade of HO following THR, the effect on post-operative opiate analgesic requirement and on patient reported outcome score. METHODS: A retrospective study was performed on 118 THRs performed without periarticular infiltration from 2003 to 2005, and on 211 performed with infiltration from 2005 to 2008. Pre-operative and 12-month radiographs were examined and HO graded according to the Brooker classification. Peri-operative analgesic requirements and NSAID use were noted and outcome was measured at 1 year with the Oxford Hip Score. RESULTS: Univariate and multivariate analysis indicated that single-dose periarticular NSAID infiltration did not reduce the incidence or grade of HO. Preoperative HO (p = 0.005) and enthesopathy (p = 0.027) were significant predictors of post-operative HO. The use of post-operative oral NSAID (except aspirin) significantly reduced HO (p = 0.001). Periarticular infiltration significantly reduced opiate analgesia use in the first 24 h (p < 0.001) and length of inpatient stay (p < 0.001). There was no difference in Oxford Hip Score at 1 year. CONCLUSION: Preoperative enthesopathies are a risk factor for postoperative HO. Periarticular infiltration of NSAID and local anaesthetic does not reduce HO incidence or grade in THR, but does reduce perioperative opiate requirements and length of hospital stay.

[Clinical study on the prevention of heterotopic ossification after total hip arthroplasty by Xiaozhong Zhitong].

OBJECTIVE: To explore the therapeutic effects of Xiaozhong Zhitong mixture preventing heterotopic ossification (HO) after total hip arthroplasty. METHODS: From July 2006 to October 2009, 154 patients underwent total hip replacement surgery were randomly divided into sham group (group A, 50 cases), indomethacin group (group B, 55 cases) and Xiaozhong Zhitong mixture group (group C, 49 cases). Among 154 patients, 9 cases were primary osteoarthris, 34 cases osteoarthritis secondary to acetabular dysplasia, 98 cases osteoarthritis secondary to avascular necrosis of the femoral head, 2 cases rheumatoid arthritis, 5 cases femoral neck fracture, 6 cases other diseases. Modified Gibson approach was used during the operation. After operation, group A was no preventing treatment, group B was treated by indomethacin 50 mg every time, twice a day; group C was treated by Xiaozhong Zhitong mixture 50 ml every time, twice a day for 4 weeks. Eighteen months after operation was study termination point and X-ray (including the double hip anteroposterior,obturator oblique and iliac oblique film) was used to observe whether heterotopic ossification was formed (Brooker classification was used to evaluate ossification degree); Harris scoring was used to evaluate the function of hip joint,including PAHSS 80 scores and IAHSS 20 scores. RESULTS: All the patients were followed up,with the average of duration of 21.2 months. The condition of heterotopic ossification: for group A,there were 27 cases with heterotopic ossification(54%) ,and Brooker I in 8 cases, II in 9 cases, III in 8 cases and IVin 2 cases; for group B, there were 12 cases heterotopic ossification (21.82%), and Brooker I in 10 cases, II in 2 cases; for group C, there were 11 cases heterotopic ossification(22.45%), and Brooker I in 9 cases, I in 2 cases. There was significant difference among three group in heterotopic ossification by rank test (P<0.05), but no difference between group B and C (P>0.05); there were no significant difference among three groups before treatment in Harris, PAHSS and IAHSS by analysis of variance (one-way ANOVA) (P>0.05), and has significant difference at 18 months after treatment (P<0.01). There were significant difference in Harris, PAHSS and IAHSS before and after treatment at 18 months (P<0.01). LSD-t was used to analyzed the scoring of Harris, PAHSS and IAHSS, there was significant difference among group A and group B and group C (P>0.05), but no difference between group B and C (P<0.01). There were gastrointestinal reaction in 5 of group A, 35 in group B and 4 in group C. CONCLUSION: The effect of Xiaozhong Zhitong mixture on the prevention of heterotopic ossification after total hip arthroplasty is similar to indomethacin, but Xiaozhong Zhitong mixture has the advantages of less side effects and easily acceptance by patients.

Lo que el clínico debe saber sobre los mecanismos de conexión entre la inflamación y la formación de hueso. ¿Es suficiente el bloqueo de la inflamación para prevenir la osificación? / What the clinician needs to know about the relationship between inflammation and bone formation. Is blocking inflammation enough to prevent ossification?

En las espondiloartropatías, la marca distintiva del daño esquelético es la neoformación ósea en forma de entesopatía calcificante, axial o periférica, y de anquilosis ósea. Las terapias biológicas que neutralizan el factor de necrosis tumoral se han mostrado eficaces para controlar la actividad inflamatoria de estas enfermedades. Sin embargo, datos procedentes de modelos animales, estudios clínicos de imagen y datos ecográficos parecen indicar que la inflamación y la formación ósea podrían ser procesos independientes y que el control de la inflamación puede no ser suficiente para impedir el desarrollo de anquilosis en estos pacientes. En la diferenciación y la activación del osteoblasto para inducir la formación ósea, la vía Wnt (wingless) y las proteínas morfogenéticas óseas adquieren un especial protagonismo y pueden ser determinantes en el comienzo y la progresión de la osificación entesítica, y convertirse en posibles dianas terapéuticas. Por otro lado, otros hallazgos clínicos, estudios de imagen y de marcadores óseos respaldarían la hipótesis de que la osificación se relaciona con la inflamación como un proceso inicialmente reparador. Se revisan estos hechos y se exponen las últimas teorías que intentan establecer el nexo entre inflamación y formación ósea (AU)

In spondyloarthropathies, the distinctive evidence of skeletal damage is de novo bone formation in the form of an ossifying enthesopathy, be it axial or peripheral, and bony ankylosis. Biologic therapy that neutralize the tumor necrosis factor have shown to be effective controlling the inflammatory activity of these diseases. However, data from animal models, clinical imaging studies and ecographic data seem to indicate that inflammation and bone formation could be independent processes and that control of inflammation might not be enough to impede the development of ankylosis in these patients. In the osteoblasts’ differentiation and activation that leads to bone formation, the Wnt (wingless) pathway and the bone morphogenic proteins acquire a special role and might be determinant in the onset and progression of enthesopathic ossification, as well as become therapeutic targets. On the other hand, clinical and imaging findings as well as the determination of bone markers support the hypothesis that that ossification is initially related to inflammation as a repair process. These facts are reviewed and the latest theories are exposed, in an attempt to establish a link between inflammation and bone formation (AU)

Long-term results of radiation prophylaxis for heterotopic ossification in the temporomandibular joint.

PURPOSE: To assess the long-term efficacy and toxicity of radiation therapy (RT) for postoperative prophylaxis of recurrent heterotopic ossification (HO) in the temporomandibular joint (TMJ). PATIENTS AND METHODS: Twelve patients (18 joints) with bony ankylosis of the TMJ from HO were referred to undergo RT after arthrotomy with osseous recontouring, gap arthroplasty, or costochondral grafting. Treatment consisted of 10 Gy in 5 daily fractions to a field encompassing the TMJ with an adequate margin. RT was initiated 1 to 3 days postoperatively. Response to therapy was assessed by routine x-ray films obtained preoperatively, immediately postoperatively, and at follow-up by use of the Turlington-Durr grading system. Treatment efficacy was defined as freedom from HO re-formation requiring further surgical intervention. Efficacy and toxicity data were obtained from review of the medical records and were augmented by telephone interview of patients when possible (6 patients, all with follow-up >16 years). Efficacy rates by patient were estimated by the Kaplan-Meier method. RESULTS: The median follow-up after RT was 16.4 years (range, 2.5-19.2 years). Symptomatic re-formation of HO requiring further surgery occurred in 5 patients (7 joints). Treatment efficacy rates were 71% (95% confidence interval [CI], 44-99) at 5 years and 48% (95% CI, 15-80) at 10 years. Of the 6 patients contacted regarding late toxicity, 2 had clinical xerostomia (grade 1, CTCAE v3.0) attributable to RT; no other late RT-related toxicities were noted. None of the 12 patients had malignancy attributable to RT. CONCLUSIONS: Postoperative RT prevented re-formation of TMJ HO in 50% of treated patients long term. Late toxicities from RT were mild and infrequent.

Pulse low-intensity electromagnetic field as prophylaxis of heterotopic ossification in patients with traumatic spinal cord injury.

BACKGROUND/AIM: Heterotopic ossification (HO) is an important complication of head and spinal cord injuries (SCI). Pulse low-intensity electromagnetic field (PLIMF) therapy increases blood flow to an area of pain or inflammation, bringing more oxygen to that area and helps to remove toxic substances. The aim of this study was to determine the effect of PLIMF as prophylaxis of HO in patients with SCI. METHODS: This prospective random control clinical study included 29 patients with traumatic SCI. The patients were randomly divided into experimental (n=14) and control group (n=15). The patients in the experimental group, besides exercise and range of motion therapy, were treated by PLIMF of the following characteristics: induction of 10 mT, frequency of 25 Hz and duration of 30 min. Pulse low-intensity electromagnetic field therapy started in the 7th week after the injury and lasted 4 weeks. The presence or absence of HO around the patients hips we checked by a plane radiography and Brookers classification. Functional capabilities and motor impairment were checked by Functional Independent Measure (FIM), Barthel index and American Spinal Injury Association (ASIA) impairment class. Statistic analysis included Kolmogorov-Smimrnov test, Shapiro-Wilk test, Mann Whitney Exact test, Exact Wilcoxon signed rank test and Fischer Exact test. Statistical significance was set up to p<0.05. RESULTS: At the end of the treatment no patient from the experimental group had HO. In the control group, five patients (33.3%) had HO. At the end of the treatment the majority of the patients from the experimental group (57.14%) moved from ASIA-A to ASIA-B class. CONCLUSION: Pulse low-intensity electromagnetic field therapy could help as prophylaxis of HO in patients with traumatic SCI.

Antioxidant N-acetyl-L-cysteine ameliorates symptoms of premature aging associated with the deficiency of the circadian protein BMAL1.

Deficiency of the circadian clock protein BMAL1 leads to premature aging and increased levels of reactivate oxygen species in several tissues of mice. In order to investigate the role of oxidative stress in accelerated aging and development of age-related pathologies, we continuously administered the antioxidant N-acetyl-L-cysteine toBmal1-deficient mice through their entire lifespan by supplementing drinking water. We found that the life long treatment with antioxidant significantly increased average and maximal lifespan and reduced the rate of age-dependent weight loss and development of cataracts. At the same time, it had no effect on time of onset and severity of other age-related pathologies characteristic of Bmal1-/- mice, such as joint ossification, reduced hair regrowth and sarcopenia. We conclude that chronic oxidative stress affects longevity and contributes to the development of at least some age-associated pathology, although ROS-independent mechanisms may also play a role. Our bioinformatics analysis identified the presence of a conservative E box element in the promoter regions of several genes encoding major antioxidant enzymes. We speculate that BMAL1 controls antioxidant defense by regulating the expression of major antioxidant enzymes.

[Sevelamer hydrochloride prevents ectopic calcification of blood vessels].

Sevelamer hydrochloride is a non-absorbed calcium- and metal-free phosphate binder that lowers the serum phosphorus levels in hemodialysis patients. Sevelamer contains multiple amines, which are partially protonated and interact with phosphate molecules through ionic and hydrogen bonding. We show the in vitro phosphate binding assay data and the efficacy of sevelamer to lower the serum phosphorus and calcium phosphorus product in several animal models. Furthermore, we indicate the vivid data that sevelamer prevented the ectopic calcification of aorta in adenine induced renal failure model, which represent severe hyperphosphatemia and the related dialysis complications.

Preventing chronic ectopic bone-related pain and disability after hip replacement surgery with perioperative ibuprofen. A multicenter, randomized, double-blind, placebo-controlled trial (HIPAID).

Postoperative ectopic bone formation affects about 40% of people undergoing elective hip replacement surgery. Despite clear evidence that a short course of perioperative nonsteroidal anti-inflammatory drugs (NSAIDs) can substantially reduce the occurrence of ectopic bone, the use of NSAID-based prophylactic therapy is uncommon in Australia or New Zealand. In part, this reflects surgeons' uncertainty about the importance of ectopic bone as a cause of impaired long-term outcome, and in part, concerns about possible increased risk for gastrointestinal complications and excess wound bleeding in patients undergoing orthopedic surgery. To address this uncertainty, a multicenter randomized controlled clinical trial is being conducted amongst 1000 patients undergoing elective total hip replacement (or revision) surgery. Patients are randomly allocated to 14 days of treatment with either 1200 mg ibuprofen (a commonly used NSAID) or matching placebo commencing within 24 h of surgery. Treatment outcomes will be assessed 6-12 months later. The primary outcome will be self-reported pain and physical function. Secondary outcomes include quality of life and physical performance measures. Patient recruitment has commenced in more than 20 orthopedic centers throughout Australia and New Zealand and will be complete by the end of October 2003. The prevention of chronic ectopic bone-related pain and disability after hip replacement surgery with anti-inflammatory drugs study (HIPAID) has been designed to provide precise and reliable information about the overall balance of risks and benefits associated with a short 14-day perioperative course of ibuprofen among individuals undergoing elective total hip replacement surgery.

Flurbiprofen inhibits heterotopic bone formation in total hip arthroplasty.

A double-blind prospective parallel group study comparing slow-release flurbiprofen with placebo in the control of ectopic bone formation was carried out in 68 patients undergoing total hip arthroplasty. Eight weeks after surgery there was evidence, significant at the 1% level, that the incidence and extent of periarticular calcification was lower in the flurbiprofen group. At an early phase, serum calcium level decreased and after 8 weeks serum alkaline phosphatase level increased more in the placebo group than in the flurbiprofen group, indicating an effect of flurbiprofen on bone mineral metabolism. Six patients were withdrawn in each treatment group, four due to side effects in the flurbiprofen group and three due to side effects in the placebo group. Overall, five patients in each group reported side effects, the nature and severity of the side effects being very similar in each group. We conclude that flurbiprofen is an efficient and safe drug in limiting ectopic bone formation following total hip arthroplasty. Heterotopic bone formation is a frequent complication after total hip replacement. Heterotopic bone reduces the extent of hip motion, reduction being more evident in cases with extensive ectopic bone formation around the hip joint. Various treatment regimens have been proposed for discouraging heterotopic bone formation. Anti-inflammatory agents such as indomethacin and ibuprofen have turned out effective. Local irradiation also prevents ectopic bone formation, but diphosphonates seem not be effective in this respect. The aim of the present study was to assess the efficacy of flurbiprofen, a new anti-inflammatory agent, in limiting heterotopic bone formation, and to note the frequency and severity of any side effects of the treatment.