Reduction in creatine metabolites in macrophages exposed to small molecule analogues of the anti-inflammatory parasitic worm product ES-62

ES-62, a protein secreted by Acanthocheilonema viteae, is anti-inflammatory by virtue of covalently attached phosphorylcholine (PC) residues and thus a library of drug-like small molecule analogues (SMAs) based on its PC moieties has been designed for therapeutic purposes. Two members, SMAs 11a and 12b, were previously found to suppress production of pro-inflammatory cytokines by mouse bone marrow-derived macrophages (BMMs) exposed to cytosine-phosphate-guanosine oligodeoxynucleotides (CpG), agonists for Toll-like receptor 9. In order to explore the mechanism of action underlying such activities, an untargeted mass spectrometry-based metabolomics screen was undertaken. Stimulation of BMMs with CpG produced significant metabolic changes relating to glycolysis and the TCA cycle but the SMAs had little impact on this. Also, the SMAs did not promote alterations in metabolites known to be associated with macrophage M1/M2 polarization. Rather, BMMs exposed to SMAs 11a or 12b prior to CpG treatment, or even alone, revealed downregulation of metabolites of creatine, a molecule whose major role is in the transport of high energy phosphate from the mitochondria to the cytosol. These data therefore provide insight into a possible mechanism of action of molecules with significant therapeutic potential that has not previously been described for parasitic worm products.

The parasitic worm product ES-62 protects against collagen-induced arthritis by resetting the gut-bone marrow axis in a microbiome-dependent manner

The parasitic worm-derived immunomodulator, ES-62 rescues defective levels of IL-10-producing regulatory B cells (Bregs) and suppresses chronic Th1/Th17-driven inflammation to protect against joint destruction in the mouse collagen-induced arthritis (CIA) model of rheumatoid arthritis. Such autoimmune arthritis is also associated with dysbiosis of the gut microbiota and disruption of intestinal barrier integrity. We recently further exploited the CIA model to show that ES-62's prevention of joint destruction is associated with protection of intestinal barrier integrity and normalization of the gut microbiota, thereby suppressing the gut pathology that precedes the onset of autoimmunity and joint damage in CIA-mice. As the status of the gut microbiota impacts on immune responses by influencing haematopoiesis, we have therefore investigated whether ES-62 harnesses the homeostatic mechanisms regulating this gut-bone marrow (BM) axis to resolve the chronic inflammation promoting autoimmunity and joint destruction in CIA. Reflecting this, ES-62 was found to counteract the BM myeloid/lymphoid bias typically associated with chronic inflammation and infection. This was achieved primarily by ES-62 acting to maintain the levels of lymphoid lineages (B220+ and CD3+ cells) observed in naïve, healthy mice but lost from the BM of CIA-mice. Moreover, ES-62's ability to prevent bone-destroying osteoclastogenesis was found to be associated with its suppression of CIA-induced upregulation of osteoclast progenitors (OCPs) in the BM. Critically, and supporting ES-62's targeting of the gut-BM axis, this rewiring of inflammatory haematopoiesis was lost in mice with a depleted microbiome. Underlining the importance of ES-62's actions in restoring steady-state haematopoiesis, the BM levels of B and T lymphoid cells were shown to be inversely correlated, whilst the levels of OCPs positively correlated, with the severity of joint damage in CIA-mice.

IĸB Protein BCL3 as a Controller of Osteogenesis and Bone Health

OBJECTIVE

IĸB protein B cell lymphoma 3-encoded protein (BCL3) is a regulator of the NF-κB family of transcription factors. NF-κB signaling fundamentally influences the fate of bone-forming osteoblasts and bone-resorbing osteoclasts, but the role of BCL3 in bone biology has not been investigated. The objective of this study was to evaluate BCL3 in skeletal development, maintenance, and osteoarthritic pathology.

METHODS

To assess the contribution of BCL3 to skeletal homeostasis, neonatal mice (n = 6-14) lacking BCL3 (Bcl3-/- ) and wild-type (WT) controls were characterized for bone phenotype and density. To reveal the contribution to bone phenotype by the osteoblast compartment in Bcl3-/- mice, transcriptomic analysis of early osteogenic differentiation and cellular function (n = 3-7) were assessed. Osteoclast differentiation and function in Bcl3-/- mice (n = 3-5) was assessed. Adult 20-week Bcl3-/- and WT mice bone phenotype, strength, and turnover were assessed. A destabilization of the medial meniscus model of osteoarthritic osteophytogenesis was used to understand adult bone formation in Bcl3-/- mice (n = 11-13).

RESULTS

Evaluation of Bcl3-/- mice revealed congenitally increased bone density, long bone dwarfism, increased bone biomechanical strength, and altered bone turnover. Molecular and cellular characterization of mesenchymal precursors showed that Bcl3-/- cells displayed an accelerated osteogenic transcriptional profile that led to enhanced differentiation into osteoblasts with increased functional activity, which could be reversed with a mimetic peptide. In a model of osteoarthritis-induced osteophytogenesis, Bcl3-/- mice exhibited decreased pathological osteophyte formation (P < 0.05).

CONCLUSION

Cumulatively, these findings demonstrate that BCL3 controls developmental mineralization to enable appropriate bone formation, whereas in a pathological setting, it contributes to skeletal pathology.

Cost-utility analysis of robotic arm-assisted medial compartment knee arthroplasty

Aims

To perform an incremental cost-utility analysis and assess the impact of differential costs and case volume on the cost-effectiveness of robotic arm-assisted unicompartmental knee arthroplasty (rUKA) compared to manual (mUKA).

Methods

This was a five-year follow-up study of patients who were randomized to rUKA (n = 64) or mUKA (n = 65). Patients completed the EuroQol five-dimension questionnaire (EQ-5D) preoperatively, and at three months and one, two, and five years postoperatively, which was used to calculate quality-adjusted life years (QALYs) gained. Costs for the primary and additional surgery and healthcare costs were calculated.

Results

rUKA was associated with a relative 0.012 QALY gain at five years, which was associated with an incremental cost per QALY of £13,078 for a unit undertaking 400 cases per year. A cost per QALY of less than £20,000 was achieved when ≥ 300 cases were performed per year. However, on removal of the cost for a revision for presumed infection (mUKA group, n = 1) the cost per QALY was greater than £38,000, which was in part due to the increased intraoperative consumable costs associated with rUKA (£626 per patient). When the absolute cost difference (operative and revision costs) was less than £240, a cost per QALY of less than £20,000 was achieved. On removing the cost of the revision for infection, rUKA was cost-neutral when more than 900 cases per year were undertaken and when the consumable costs were zero.

Conclusion

rUKA was a cost-effective intervention with an incremental cost per QALY of £13,078 at five years, however when removing the revision for presumed infection, which was arguably a random event, this was no longer the case. The absolute cost difference had to be less than £240 to be cost-effective, which could be achieved by reducing the perioperative costs of rUKA or if there were increased revision costs associated with mUKA with longer follow-up.

Protection against lung pathology during obesity-accelerated ageing in mice by the parasitic worm product ES-62

Mice develop pathology in the lungs as they age and this may be accelerated by a high calorie diet (HCD). ES-62 is a protein secreted by the parasitic worm Acanthocheilonema viteae that is immunomodulatory by virtue of covalently attached phosphorylcholine (PC) moieties. In this study, we show that weekly treatment of C57BL/6J mice with ES-62 protected against pathology in the lungs in male but not female mice fed a HCD from 10 weeks of age as shown by reductions in cellular infiltration and airway remodelling, particularly up to 160 days of age. ES-62 also reduced gene expression of the cytokines IL-4 and IL-17 and in addition the TLR/IL-1R adaptor MyD88, in the lungs of male mice although HCD-induced increases in these inflammatory markers were not detected until between 340 and 500 days of age. A combination of two drug-like ES-62 PC-based small molecule analogues (SMAs), produced broadly similar protective effects in the lungs of male mice with respect to both lung pathology and inflammatory markers, in addition to a decrease in HCD-induced IL-5 expression. Overall, our data show that ES-62 and its SMAs offer protection against HCD-accelerated pathological changes in the lungs during ageing. Given the targeting of Th2 cytokines and IL-17, we discuss this protection in the context of ES-62's previously described amelioration of airway hyper-responsiveness in mouse models of asthma.

Survivorship of high tibial osteotomy in the treatment of osteoarthritis of the knee: a retrospective cohort study with fourteen years' follow-up

PURPOSE

This study was to evaluate the survivorship of HTO for the treatment of medial compartment osteoarthritis (OA) in young and active patients from two teaching hospitals in a single city.

METHODS

This is a retrospective cohort multicenter study looking at HTO for treatment of medial compartment OA. We analyzed a case series of HTO's performed by four surgeons in two centres over a 14-year period. Failure was defined as conversion to total knee replacement (TKR). All cases where additional procedures for instability of the knee were performed at the time of the index surgery were excluded. Time to failure was recorded, and a Kaplan-Meir (KM) analysis was performed to evaluate survivorship. Univariate binary regression analysis was undertaken to identify associations between risk factors and failure.

RESULTS

A total of 96 patients were included in the study with a median age was 45 years. The survivorship at five years post-op was 90.3%, and at ten years post-op, it was 82%. Patients that were 14 years after surgery had a survivorship of 65%. Also, 18.8% of patients required the removal of their metalwork. The overall complication rate was 6.3%. The univariate regression analysis showed that higher age (p = 0.02) and larger corrections requiring the use of bone graft increased the risk of failure (p = 0.02). There was no statistically significant correlation between laterality, gender, complication rate, and pre-operative alignment to survivorship.

CONCLUSION

This is one of the largest reported case series of HTO's with comparable survivorship at five and ten year follow-up compared to the reported literature. There was an association found between increasing age and larger corrections requiring bone graft at index procedure to increasing failure rate.

The parasitic worm product ES-62 protects the osteoimmunology axis in a mouse model of obesity-accelerated ageing

Despite significant increases in human lifespan over the last century, adoption of high calorie diets (HCD) has driven global increases in type-2 diabetes, obesity and cardiovascular disease, disorders precluding corresponding improvements in healthspan. Reflecting that such conditions are associated with chronic systemic inflammation, evidence is emerging that infection with parasitic helminths might protect against obesity-accelerated ageing, by virtue of their evolution of survival-promoting anti-inflammatory molecules. Indeed, ES-62, an anti-inflammatory secreted product of the filarial nematode Acanthocheilonema viteae, improves the healthspan of both male and female C57BL/6J mice undergoing obesity-accelerated ageing and also extends median lifespan in male animals, by positively impacting on inflammatory, adipose metabolic and gut microbiome parameters of ageing. We therefore explored whether ES-62 affects the osteoimmunology axis that integrates environmental signals, such as diet and the gut microbiome to homeostatically regulate haematopoiesis and training of immune responses, which become dysregulated during (obesity-accelerated) ageing. Of note, we find sexual dimorphisms in the decline in bone health, and associated dysregulation of haematopoiesis and consequent peripheral immune responses, during obesity-accelerated ageing, highlighting the importance of developing sex-specific anti-ageing strategies. Related to this, ES-62 protects trabecular bone structure, maintaining bone marrow (BM) niches that counter the ageing-associated decline in haematopoietic stem cell (HSC) functionality highlighted by a bias towards myeloid lineages, in male but not female, HCD-fed mice. This is evidenced by the ability of ES-62 to suppress the adipocyte and megakaryocyte bias and correspondingly promote increases in B lymphocytes in the BM. Furthermore, the consequent prevention of ageing-associated myeloid/lymphoid skewing is associated with reduced accumulation of inflammatory CD11c+ macrophages and IL-1β in adipose tissue, disrupting the perpetuation of inflammation-driven dysregulation of haematopoiesis during obesity-accelerated ageing in male HCD-fed mice. Finally, we report the ability of small drug-like molecule analogues of ES-62 to mimic some of its key actions, particularly in strongly protecting trabecular bone structure, highlighting the translational potential of these studies.

Are there functional biomechanical differences in robotic arm-assisted bi-unicompartmental knee arthroplasty compared with conventional total knee arthroplasty? A prospective, randomized controlled trial

AIMS

The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery.

METHODS

A total of 76 patients (34 bi-UKA and 42 TKA patients) were analyzed in a prospective, single-centre, randomized controlled trial. Flat ground shod gait analysis was performed preoperatively and one year postoperatively. Knee flexion moment was calculated from motion capture markers and force plates. The same setup determined proprioception outcomes during a joint position sense test and one-leg standing. Surgery allocation, surgeon, and secondary outcomes were analyzed for prediction of the primary outcome from a binary regression model.

RESULTS

Both interventions were shown to be effective treatment options, with no significant differences shown between interventions for the primary outcome of this study (18/35 (51.4%) biphasic TKA patients vs 20/31 (64.5%) biphasic bi-UKA patients; p = 0.558). All outcomes were compared to an age-matched, healthy cohort that outperformed both groups, indicating residual deficits exists following surgery. Logistic regression analysis of primary outcome with secondary outcomes indicated that the most significant predictor of postoperative biphasic knee moments was preoperative knee moment profile and trochlear degradation (Outerbridge) (R² = 0.381; p = 0.002, p = 0.046). A separate regression of alignment against primary outcome indicated significant bi-UKA femoral and tibial axial alignment (R² = 0.352; p = 0.029), and TKA femoral sagittal alignment (R² = 0.252; p = 0.016). The bi-UKA group showed a significant increased ability in the proprioceptive joint position test, but no difference was found in more dynamic testing of proprioception.

CONCLUSION

Robotic arm-assisted bi-UKA demonstrated equivalence to TKA in achieving a biphasic gait pattern after surgery for osteoarthritis of the knee. Both treatments are successful at improving gait, but both leave the patients with a functional limitation that is not present in healthy age-matched controls. Cite this article: Bone Joint J 2022;103-B(4):433-443.

Does the modified Glasgow Prognostic Score aid in the management of patients undergoing surgery for a soft-tissue sarcoma? : an international multicentre study

AIMS

The modified Glasgow Prognostic Score (mGPS) uses preoperative CRP and albumin to calculate a score from 0 to 2 (2 being associated with poor outcomes). mGPS is validated in multiple carcinomas. To date, its use in soft-tissue sarcoma (STS) is limited, with only small cohorts reporting that increased mGPS scores correlates with decreased survival in STS patients.

METHODS

This retrospective multicentre cohort study identified 493 STS patients using clinical databases from six collaborating hospitals in three countries. Centres performed a retrospective data collection for patient demographics, preoperative blood results (CRP and albumin levels and neutrophil, leucocyte, and platelets counts), and oncological outcomes (disease-free survival, local, or metastatic recurrence) with a minimum of two years' follow-up.

RESULTS

We found that increased mGPS, tumour size, grade, neutrophil/lymphocyte ratio, and disease recurrence were associated with reduced survival. Importantly, mGPS was the best at stratifying prognosis and could be used in conjunction with tumour grade to sub-stratify patient survival.

CONCLUSION

This study demonstrated that prognosis of localized STS strongly correlates with mGPS, as an increasing score is associated with a poorer outcome. We note that 203 patients (41%) with an STS have evidence of systemic inflammation. We recommend the mGPS and other biochemical blood indicators be introduced into the routine diagnostic assessment in STS patients to stratify patient prognosis. Its use will support clinical decision-making, especially when morbid treatment options such as amputation are being considered. Cite this article: Bone Joint J 2022;104-B(1):168-176.

Closed incision negative pressure wound therapy versus conventional dressings following soft-tissue sarcoma excision: a prospective, randomized controlled trial

Aims

The primary objective of this study was to compare the postoperative infection rate between negative pressure wound therapy (NPWT) and conventional dressings for closed incisions following soft-tissue sarcoma (STS) surgery. Secondary objectives were to compare rates of adverse wound events and functional scores.

Methods

In this prospective, single-centre, randomized controlled trial (RCT), patients were randomized to either NPWT or conventional sterile occlusive dressings. A total of 17 patients, with a mean age of 54 years (21 to 81), were successfully recruited and none were lost to follow-up. Wound reviews were undertaken to identify any surgical site infection (SSI) or adverse wound events within 30 days. The Toronto Extremity Salvage Score (TESS) and Musculoskeletal Tumor Society (MSTS) score were recorded as patient-reported outcome measures (PROMs).

Results

There were two out of seven patients in the control group (28.6%), and two out of ten patients in the intervention group (20%) who were diagnosed with a SSI (p > 0.999), while one additional adverse wound event was identified in the control group (p = 0.593). No significant differences in PROMs were identified between the groups at either 30 days (TESS, p = 0.987; MSTS, p = 0.951) or six-month (TESS, p = 0.400) follow-up. However, neoadjuvant radiotherapy was significantly associated with a SSI within 30 days of surgery, across all patients (p = 0.029). The mean preoperative modified Glasgow Prognostic Score (mGPS) was also significantly higher among patients who developed a postoperative adverse wound event (p = 0.028), including a SSI (p = 0.008), across both groups.

Conclusion

This is the first RCT comparing NPWT with conventional dressings following musculoskeletal tumour surgery. Postoperative wound complications are common in this group of patients and we observed an overall SSI rate of 23.5%. We propose proceeding to a multicentre trial, which will help more clearly define the role of closed incision NPWT in STS surgery.

Cite this article: Bone Jt Open 2021;2(12):1049–1056.

Inflammatory prognostic scoring systems are risk factors for surgical site infection following wide local excision of soft tissue sarcoma

Introduction

Limb-sparing surgery with negative margins is possible in most soft tissue sarcoma (STS) resections and focuses on maximising function and minimising morbidity. Various risk factors for surgical site infections (SSIs) have been reported in the literature specific to sarcoma surgery. The aim of this study is to determine whether systemic inflammatory response prognostic scoring systems can predict post-operative SSI in patients undergoing potentially curative resection of STS.

Methods

Patients who had a planned curative resection of a primary STS at a single centre between January 2010 and December 2019 with a minimum follow-up of 6 months were included. Data were extracted on patient and tumour characteristics, and pre-operative blood results were used to calculate inflammatory prognostic scores based on published thresholds and correlated with risk of developing SSI or debridement procedures.

Results

A total of 187 cases were included. There were 60 SSIs. On univariate analysis, there was a statistically significant increased risk of SSI in patients who are diabetic, increasing specimen diameter, American Society of Anaesthesiology (ASA) grade 3, use of endoprosthetic replacement, blood loss greater than 1 L, and junctional tumour location. Modified Glasgow prognostic score, C-reactive protein/albumin ratio and neutrophil–platelet score (NPS) were statistically associated with the risk of SSI. On multivariate analysis, ASA grade 3, junctional tumour location and NPS were independently associated with the risk of developing a SSI.

Conclusion

This study supports the routine use of simple inflammation-based prognostic scores in identifying patients at increased risk of developing infectious complications in patients undergoing potentially curative resection of STS.

Electromagnetic Navigated Versus Conventional Total Knee Arthroplasty-A Five-Year Follow-Up of a Single-Blind Randomized Control Trial

BACKGROUND

The objective of this study is to provide the 5-year follow-up results of a randomized study comparing conventional versus electromagnetic computer navigated total knee arthroplasty.

METHODS

Analysis of 127 patients (66 navigated and 61 conventional surgeries) was performed from a prospective, single-blinded, randomized controlled trial. Patient-reported outcome measures were collected at 5 years after surgery and compared with previously published 1-year clinical outcomes. Five-year surgical revision rates were collated and compared between intervention groups.

RESULTS

Overall, there have been continued improvements in the clinical scores of patients in both groups when compared with clinical data at 1 year; however, at 5 years, there is no statistical difference in any of the patient-reported outcome measures between conventional and navigated surgery. Interestingly, improved implant survivorship was observed in the navigated (0% revision rate) compared with the conventional group (4.9% all-cause revision rate).

CONCLUSION

Electromagnetic computer navigated technology produces similar clinical outcomes compared with traditional surgery. Further work is required to monitor implant survivorship, and clinical outcomes with long-term follow-up, to determine the cost effectiveness of this technology.

Early outcomes after robotic arm-assisted bi-unicompartmental knee arthroplasty compared with total knee arthroplasty: a prospective, randomized controlled trial

AIMS

The aim of this study was to compare the clinical outcomes of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) during the first six weeks and at one year postoperatively.

METHODS

A per protocol analysis of 76 patients, 43 of whom underwent TKA and 34 of whom underwent bi-UKA, was performed from a prospective, single-centre, randomized controlled trial. Diaries kept by the patients recorded pain, function, and the use of analgesics daily throughout the first week and weekly between the second and sixth weeks. Patient-reported outcome measures (PROMs) were compared preoperatively, and at three months and one year postoperatively. Data were also compared longitudinally and a subgroup analysis was conducted, stratified by preoperative PROM status.

RESULTS

Both operations were shown to offer comparable outcomes, with no significant differences between the groups across all timepoints and outcome measures. Both groups also had similarly low rates of complications. Subgroup analysis for preoperative psychological state, activity levels, and BMI showed no difference in outcomes between the two groups.

CONCLUSION

Robotic arm-assisted, cruciate-sparing bi-UKA offered similar early clinical outcomes and rates of complications to a mechanically aligned TKA, both in the immediate postoperative period and up to one year following surgery. Further work is required to identify which patients with osteoarthritis of the knee will derive benefit from a cruciate-sparing bi-UKA. Cite this article: Bone Joint J 2021;103-B(10):1561-1570.

Significant differences in rates of aseptic loosening between two variations of a popular total knee arthroplasty design

Purpose

The NexGen Legacy Posterior Stabilised (LPS) prosthesis (Zimmer Biomet, Warsaw, IN, USA) has augmentable and non-augmentable tibial baseplate options. We have noted an anecdotal increase in the number of cases requiring early revision for aseptic loosening since adopting the non-augmentable option. The purpose of this study was to ascertain our rates of aseptic tibial loosening for the two implant types within five years of implantation and to investigate the causes for any difference observed.

Methods

A database search was performed for all patients who underwent primary total knee arthroplasty (TKA) using the NexGen LPS between 2009 and 2015. Kaplan–Meier curves were plotted to assess for differences in revision rates between cohorts. We collected and compared data on gender, age, body mass index, component alignment and cement mantle quality as these were factors thought to affect the likelihood of aseptic loosening.

Results

Two thousand one hundred seventy-two TKAs were included with five year follow-up. There were 759 augmentable knees of which 14 were revised and 1413 non-augmentable knees of which 48 were revised. The overall revision rate at five years was 1.84% in the augmentable cohort and 3.4% in the non-augmentable cohort. The revision rate for aseptic loosening was 0.26% in the augmentable group and 1.42% in the non-augmentable group (p = 0.0241).

Conclusions

We have identified increased rates of aseptic loosening in non-augmentable components. This highlights the effect that minor implant changes can have on outcomes. We recommend that clinicians remain alert to implant changes and publish their own results when important trends are observed.

Robotic arm-assisted versus conventional medial unicompartmental knee arthroplasty: five-year clinical outcomes of a randomized controlled trial

Aims

Unicompartmental knee arthroplasty (UKA) is a bone-preserving treatment option for osteoarthritis localized to a single compartment in the knee. The success of the procedure is sensitive to patient selection and alignment errors. Robotic arm-assisted UKA provides technological assistance to intraoperative bony resection accuracy, which is thought to improve ligament balancing. This paper presents the five-year outcomes of a comparison between manual and robotically assisted UKAs.

Methods

The trial design was a prospective, randomized, parallel, single-centre study comparing surgical alignment in patients undergoing UKA for the treatment of medial compartment osteoarthritis (ISRCTN77119437). Participants underwent surgery using either robotic arm-assisted surgery or conventional manual instrumentation. The primary outcome measure (surgical accuracy) has previously been reported, and, along with secondary outcomes, were collected at one-, two-, and five-year timepoints. Analysis of five-year results and longitudinal analysis for all timepoints was performed to compare the two groups.

Results

Overall, 104 (80%) patients of the original 130 who received surgery were available at five years (55 robotic, 49 manual). Both procedures reported successful results over all outcomes. At five years, there were no statistical differences between the groups in any of the patient reported or clinical outcomes. There was a lower reintervention rate in the robotic arm-assisted group with 0% requiring further surgery compared with six (9%) of the manual group requiring additional surgical intervention (p < 0.001).

Conclusion

This study has shown excellent clinical outcomes in both groups with no statistical or clinical differences in the patient-reported outcome measures. The notable difference was the lower reintervention rate at five years for roboticarm-assisted UKA when compared with a manual approach.

Cite this article: Bone Joint J 2021;103-B(6):1088–1095.

Development of Acanthocheilonema viteae in Meriones shawi: Absence of microfilariae and production of active ES-62

AIMS

ES-62 is a well-studied anti-inflammatory molecule secreted by L4-adult stage Acanthocheilonema viteae. We maintain the life cycle of A viteae using Meriones libycus as the definitive host. Here, we investigated whether the full life cycle could be maintained, and functional ES-62 produced, in a related jird species-Meriones shawi.

METHODS AND RESULTS

Adult worms were produced in comparable numbers in the two species, but very few microfilariae (MF) were observed in the M shawi bloodstream. M shawi ES-62 produced ex vivo was functional and protective in a mouse model of arthritis. Myeloid-derived cells from naïve and infected jirds of both species were compared with respect to ROS production and osteoclast generation, and some differences between the two species in both the absence and presence of infection were observed.

CONCLUSIONS

The life cycle of A viteae cannot be successfully completed in M shawi jirds but L3 stage worms develop to adulthood and produce functional ES-62. Preliminary investigation into jird immune responses suggests that infection can differentially modulate myeloid responses in the two species. However, species-specific reagents are required to understand the complex interplay between A viteae and its host and to explain the lack of circulating MF in infected M shawi jirds.

Robotic arm-assisted bi-unicompartmental knee arthroplasty maintains natural knee joint anatomy compared with total knee arthroplasty: a prospective randomized controlled trial

AIMS

The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery.

METHODS

An analysis of 38 patients who underwent TKA and 32 who underwent bi-UKA was performed as a secondary study from a prospective, single-centre, randomized controlled trial. CT imaging was used to measure coronal, sagittal, and axial alignment of the knee preoperatively and at three months postoperatively to determine changes in anatomy that had occurred as a result of the surgery. The hip-knee-ankle angle (HKAA) was also measured to identify any differences between the two groups.

RESULTS

The pre- to postoperative changes in joint anatomy were significantly less in patients undergoing bi-UKA in all three planes in both the femur and tibia, except for femoral sagittal component orientation in which there was no difference. Overall, for the six parameters of alignment (three femoral and three tibial), 47% of bi-UKAs and 24% TKAs had a change of < 2° (p = 0.045). The change in HKAA towards neutral in varus and valgus knees was significantly less in patients undergoing bi-UKA compared with those undergoing TKA (p < 0.001). Alignment was neutral in those undergoing TKA (mean 179.5° (SD 3.2°)) while those undergoing bi-UKA had mild residual varus or valgus alignment (mean 177.8° (SD 3.4°)) (p < 0.001).

CONCLUSION

Robotic-assisted, cruciate-sparing bi-UKA maintains the natural anatomy of the knee in the coronal, sagittal, and axial planes better, and may therefore preserve normal joint kinematics, compared with a mechanically aligned TKA. This includes preservation of coronal joint line obliquity. HKAA alignment was corrected towards neutral significantly less in patients undergoing bi-UKA, which may represent restoration of the pre-disease constitutional alignment (p < 0.001). Cite this article: Bone Joint J 2020;102-B(11):1511-1518.

The parasitic worm product ES-62 promotes health- and life-span in a high calorie diet-accelerated mouse model of ageing

Improvements in hygiene and health management have driven significant increases in human lifespan over the last 50 years. Frustratingly however, this extension of lifespan has not been matched by equivalent improvements in late-life health, not least due to the global pandemic in type-2 diabetes, obesity and cardiovascular disease, all ageing-associated conditions exacerbated and accelerated by widespread adoption of the high calorie Western diet (HCD). Recently, evidence has begun to emerge that parasitic worm infection might protect against such ageing-associated co-morbidities, as a serendipitous side-effect of their evolution of pro-survival, anti-inflammatory mechanisms. As a novel therapeutic strategy, we have therefore investigated the potential of ES-62, an anti-inflammatory secreted product of the filarial nematode Acanthocheilonema viteae, to improve healthspan (the period of life before diseases of ageing appear) by targeting the chronic inflammation that drives metabolic dysregulation underpinning ageing-induced ill-health. We administered ES-62 subcutaneously (at a dose of 1 μg/week) to C57BL/6J mice undergoing HCD-accelerated ageing throughout their lifespan, while subjecting the animals to analysis of 120 immunometabolic responses at various time-points. ES-62 improved a number of inflammatory parameters, but markedly, a range of pathophysiological, metabolic and microbiome parameters of ageing were also successfully targeted. Notably, ES-62-mediated promotion of healthspan in male and female HCD-mice was associated with different mechanisms and reflecting this, machine learning modelling identified sex-specific signatures predictive of ES-62 action against HCD-accelerated ageing. Remarkably, ES-62 substantially increased the median survival of male HCD-mice. This was not the case with female animals and unexpectedly, this difference between the two sexes could not be explained in terms of suppression of the chronic inflammation driving ageing, as ES-62 tended to be more effective in reducing this in female mice. Rather, the difference appeared to be associated with ES-62's additional ability to preferentially promote a healthier gut-metabolic tissue axis in male animals.

Site-specific glycoproteomic characterization of ES-62: The major secreted product of the parasitic worm Acanthocheilonema viteae

ES-62 is the major secreted product of the parasitic filarial nematode Acanthocheilonema viteae and has potent anti-inflammatory activities as a consequence of posttranslational decoration by phosphorylcholine (PC). Previously, we showed that ES-62’s PC was attached to N-linked glycans, and using fast atom bombardment mass spectrometry, we characterized the structure of the glycans. However, it was unknown at this time which of ES-62’s four potential N-glycosylation sites carries the PC-modified glycans. In the present study, we now employ more advanced analytical tools—nano-flow liquid chromatography with high-definition electrospray mass spectrometry—to show that PC-modified glycans are found at all four potential N-glycosylation sites. Also, our earlier studies showed that up to two PC groups were detected per glycan, and we are now able to characterize N-glycans with up to five PC groups. The number per glycan varies in three of the four glycosylation sites, and in addition, for the first time, we have detected PC on the N-glycan chitobiose core in addition to terminal GlcNAc. Nevertheless, the majority of PC is detected on terminal GlcNAc, enabling it to interact with the cells and molecules of the immune system. Such expression may explain the potent immunomodulatory effects of a molecule that is considered to have significant therapeutic potential in the treatment of certain human allergic and autoimmune conditions.

Survival of Brenneria goodwinii and Gibbsiella quercinecans, associated with acute oak decline, in rainwater and forest soil

Acute oak decline (AOD) affects native UK oak species causing rapid decline and mortality in as little as five years. A major symptom of AOD is black weeping stem lesions associated with bacterial phytopathogens, Brenneria goodwinii and Gibbsiella quercinecans. However, there is limited knowledge on the ecological and environmental reservoirs of these phytopathogens. Rainwater and soils are common reservoirs of plant pathogens in a forest environment; therefore, the aim of this study was to investigate the survival of B. goodwinii and G. quercinecans in vitro when inoculated into rainwater and forest soil using a combination of agar-based colony counts and gyrB gene-targeted quantitative PCR (qPCR). Brenneria goodwinii lost viability on inoculation into soil and rainwater, but was detectable at low abundance in soil for 28 days using qPCR, suggesting a limited ability to persist outside of the host, potentially in a viable but non-culturable (VBNC) state. Conversely, Gibbsiella quercinecans, was re-isolated from rainwater for the entire duration of the experiment (84 days) and was re-isolated from forest soil after 28 days, with qPCR analysis corroborating these trends. These data demonstrate that B. goodwinii is unable to survive in forest soils and rainwater, suggesting that it may be an endosymbiont of oak trees, whereas G. quercinecans remains viable in soil and rainwater biomes, suggesting a broad ecological distribution. These data advance understanding of the potential epidemiology of AOD-associated bacteria and their ecological reservoirs, thus increasing the overall knowledge of the pathology of AOD, which assists the development of future management strategies.

Synthetic small molecule analogues of the immunomodulatory Acanthocheilonema viteae product ES-62 promote metabolic homeostasis during obesity in a mouse model

One of the most rapidly increasing human public health problems is obesity, whose sequelae like type-2 diabetes, represent continuously worsening, life-long conditions. Over the last 15 years, data have begun to emerge from human and more frequently, mouse studies, that support the idea that parasitic worm infection can protect against this condition. We have therefore investigated the potential of two synthetic small molecule analogues (SMAs) of the anti-inflammatory Acanthocheilonema viteae product ES-62, to protect against metabolic dysfunction in a C57BL/6 J mouse model of high calorie diet-induced obesity. We found weekly subcutaneous administration of the SMAs in combination (1 μg of each), starting one week before continuous exposure to high calorie diet (HCD), decreased fasting glucose levels and reversed the impaired glucose clearance observed in male mice, when measured at approximately 7 and 13 weeks after exposure to HCD. Fasting glucose levels were also-reduced in male mice fed a HCD for some 38 weeks when given SMA-treatment 13 weeks after the start of HCD, indicating an SMA-therapeutic potential. For the most part, protective effects were not observed in female mice. SMA treatment also conferred protection against each of reduced ileum villus length and liver fibrosis, but more prominently in female mice. Previous studies in mice indicate that protection against metabolic dysfunction is usually associated with polarisation of the immune system towards a type-2/anti-inflammatory direction but our attempts to correlate improved metabolic parameters with such changes were unsuccessful. Further analysis will therefore be required to define mechanism of action. Nevertheless, overall our data clearly show the potential of the drug-like SMAs as a preventative or treatment for metabolic dysregulation associated with obesity.

Genomic analysis of bacteria in the Acute Oak Decline pathobiome

The UK’s native oak is under serious threat from Acute Oak Decline (AOD). Stem tissue necrosis is a primary symptom of AOD and several bacteria are associated with necrotic lesions. Two members of the lesion pathobiome, Brenneria goodwinii and Gibbsiella quercinecans, have been identified as causative agents of tissue necrosis. However, additional bacteria including Lonsdalea britannica and Rahnella species have been detected in the lesion microbiome, but their role in tissue degradation is unclear. Consequently, information on potential genome-encoded mechanisms for tissue necrosis is critical to understand the role and mechanisms used by bacterial members of the lesion pathobiome in the aetiology of AOD. Here, the whole genomes of bacteria isolated from AOD-affected trees were sequenced, annotated and compared against canonical bacterial phytopathogens and non-pathogenic symbionts. Using orthologous gene inference methods, shared virulence genes that retain the same function were identified. Furthermore, functional annotation of phytopathogenic virulence genes demonstrated that all studied members of the AOD lesion microbiota possessed genes associated with phytopathogens. However, the genome of B. goodwinii was the most characteristic of a necrogenic phytopathogen, corroborating previous pathological and metatranscriptomic studies that implicate it as the key causal agent of AOD lesions. Furthermore, we investigated the genome sequences of other AOD lesion microbiota to understand the potential ability of microbes to cause disease or contribute to pathogenic potential of organisms isolated from this complex pathobiome. The role of these members remains uncertain but some such as G. quercinecans may contribute to tissue necrosis through the release of necrotizing enzymes and may help more dangerous pathogens activate and realize their pathogenic potential or they may contribute as secondary/opportunistic pathogens with the potential to act as accessory species for B. goodwinii. We demonstrate that in combination with ecological data, whole genome sequencing provides key insights into the pathogenic potential of bacterial species whether they be phytopathogens, part-contributors or stimulators of the pathobiome.

The parasitic worm product ES-62 normalises the gut microbiota bone marrow axis in inflammatory arthritis

The human immune system has evolved in the context of our colonisation by bacteria, viruses, fungi and parasitic helminths. Reflecting this, the rapid eradication of pathogens appears to have resulted in reduced microbiome diversity and generation of chronically activated immune systems, presaging the recent rise of allergic, autoimmune and metabolic disorders. Certainly, gastrointestinal helminths can protect against gut and lung mucosa inflammatory conditions by modulating the microbiome and suppressing the chronic inflammation associated with dysbiosis. Here, we employ ES-62, an immunomodulator secreted by tissue-dwelling Acanthocheilonema viteae to show that helminth-modulation of the gut microbiome does not require live infection with gastrointestinal-based worms nor is protection restricted to mucosal diseases. Specifically, subcutaneous administration of this defined immunomodulator affords protection against joint disease in collagen-induced arthritis, a mouse model of rheumatoid arthritis, which is associated with normalisation of gut microbiota and prevention of loss of intestinal barrier integrity.

Failure of the Anti-Inflammatory Parasitic Worm Product ES-62 to Provide Protection in Mouse Models of Type I Diabetes, Multiple Sclerosis, and Inflammatory Bowel Disease

Parasitic helminths and their isolated secreted products show promise as novel treatments for allergic and autoimmune conditions in humans. Foremost amongst the secreted products is ES-62, a glycoprotein derived from Acanthocheilonema viteae, a filarial nematode parasite of gerbils, which is anti-inflammatory by virtue of covalently-attached phosphorylcholine (PC) moieties. ES-62 has been found to protect against disease in mouse models of rheumatoid arthritis, systemic lupus erythematosus, and airway hyper-responsiveness. Furthermore, novel PC-based synthetic small molecule analogues (SMAs) of ES-62 have recently been demonstrated to show similar anti-inflammatory properties to the parent molecule. In spite of these successes, we now show that ES-62 and its SMAs are unable to provide protection in mouse models of certain autoimmune conditions where other helminth species or their secreted products can prevent disease development, namely type I diabetes, multiple sclerosis and inflammatory bowel disease. We speculate on the reasons underlying ES-62's failures in these conditions and how the negative data generated may help us to further understand ES-62's mechanism of action.

Protection Against Arthritis by the Parasitic Worm Product ES-62, and Its Drug-Like Small Molecule Analogues, Is Associated With Inhibition of Osteoclastogenesis

The immunomodulatory actions of parasitic helminth excretory-secretory (ES) products that serendipitously protect against development of chronic inflammatory disorders are well established: however, knowledge of the interaction between ES products and the host musculoskeletal system in such diseases is limited. In this study, we have focused on ES-62, a glycoprotein secreted by the rodent filarial nematode Acanthocheilonema viteae that is immunomodulatory by virtue of covalently attached phosphorylcholine (PC) moieties, and also two synthetic drug-like PC-based small molecule analogues (SMAs) that mimic ES-62's immunomodulatory activity. We have previously shown that each of these molecules prevents development of pathology in collagen-induced arthritis (CIA), a model of the musculoskeletal disease rheumatoid arthritis (RA) and reflecting this, we now report that ES-62 and its SMAs, modify bone remodeling by altering bone marrow progenitors and thus impacting on osteoclastogenesis. Consistent with this, we find that these molecules inhibit functional osteoclast differentiation in vitro. Furthermore, this appears to be achieved by induction of anti-oxidant response gene expression, thereby resulting in reduction of the reactive oxygen species production that is necessary for the increased osteoclastogenesis witnessed in musculoskeletal diseases like RA.

Integrated multi-omic analysis of host-microbiota interactions in acute oak decline

BACKGROUND

Britain's native oak species are currently under threat from acute oak decline (AOD), a decline-disease where stem bleeds overlying necrotic lesions in the inner bark and larval galleries of the bark-boring beetle, Agrilus biguttatus, represent the primary symptoms. It is known that complex interactions between the plant host and its microbiome, i.e. the holobiont, significantly influence the health status of the plant. In AOD, necrotic lesions are caused by a microbiome shift to a pathobiome consisting predominantly of Brenneria goodwinii, Gibbsiella quercinecans, Rahnella victoriana and potentially other bacteria. However, the specific mechanistic processes of the microbiota causing tissue necrosis, and the host response, have not been established and represent a barrier to understanding and managing this decline.

RESULTS

We profiled the metagenome, metatranscriptome and metaproteome of inner bark tissue from AOD symptomatic and non-symptomatic trees to characterise microbiota-host interactions. Active bacterial virulence factors such as plant cell wall-degrading enzymes, reactive oxygen species defence and flagella in AOD lesions, along with host defence responses including reactive oxygen species, cell wall modification and defence regulators were identified. B. goodwinii dominated the lesion microbiome, with significant expression of virulence factors such as the phytopathogen effector avrE. A smaller proportion of microbiome activity was attributed to G. quercinecans and R. victoriana. In addition, we describe for the first time the potential role of two previously uncharacterised Gram-positive bacteria predicted from metagenomic binning and identified as active in the AOD lesion metatranscriptome and metaproteome, implicating them in lesion formation.

CONCLUSIONS

This multi-omic study provides novel functional insights into microbiota-host interactions in AOD, a complex arboreal decline disease where polymicrobial-host interactions result in lesion formation on tree stems. We present the first descriptions of holobiont function in oak health and disease, specifically, the relative lesion activity of B. goodwinii, G. quercinecans, Rahnella victoriana and other bacteria. Thus, the research presented here provides evidence of some of the mechanisms used by members of the lesion microbiome and a template for future multi-omic research into holobiont characterisation, plant polymicrobial diseases and pathogen defence in trees.

Dendritic cells provide a therapeutic target for synthetic small molecule analogues of the parasitic worm product, ES-62

ES-62, a glycoprotein secreted by the parasitic filarial nematode Acanthocheilonema viteae, subverts host immune responses towards anti-inflammatory phenotypes by virtue of covalently attached phosphorylcholine (PC). The PC dictates that ES-62 exhibits protection in murine models of inflammatory disease and hence a library of drug-like PC-based small molecule analogues (SMAs) was synthesised. Four sulfone-containing SMAs termed 11a, 11e, 11i and 12b were found to reduce mouse bone marrow-derived dendritic cell (DC) pathogen-associated molecular pattern (PAMP)-induced pro-inflammatory cytokine production, inhibit NF-κB p65 activation, and suppress LPS-induced up-regulation of CD40 and CD86. Active SMAs also resulted in a DC phenotype that exhibited reduced capacity to prime antigen (Ag)-specific IFN-γ production during co-culture with naïve transgenic TCR DO.11.10 T cells in vitro and reduced their ability, following adoptive transfer, to prime the expansion of Ag-specific T lymphocytes, specifically TH17 cells, in vivo. Consistent with this, mice receiving DCs treated with SMAs exhibited significantly reduced severity of collagen-induced arthritis and this was accompanied by a significant reduction in IL-17+ cells in the draining lymph nodes. Collectively, these studies indicate that drug-like compounds that target DCs can be designed from parasitic worm products and demonstrate the potential for ES-62 SMA-based DC therapy in inflammatory disease.

Testing small molecule analogues of the Acanthocheilonema viteae immunomodulator ES-62 against clinically relevant allergens

ES-62 is a glycoprotein secreted by the filarial nematode Acanthocheilonema viteae that protects against ovalbumin (OVA)-induced airway hyper-responsiveness in mice by virtue of covalently attached anti-inflammatory phosphorylcholine (PC) residues. We have recently generated a library of small molecule analogues (SMAs) of ES-62 based around its active PC moiety as a starting point in novel drug development for asthma and identified two compounds - termed 11a and 12b - that mirror ES-62's protective effects. In this study, we have moved away from OVA, a model allergen, to test the SMAs against two clinically relevant allergens - house dust mite (HDM) and cockroach allergen (CR) extract. We show that both SMAs offer some protection against development of lung allergic responses to CR, in particular reducing eosinophil infiltration, whereas only SMA 12b is effective in protecting against eosinophil-dependent HDM-induced allergy. These data therefore suggest that helminth molecule-induced protection against model allergens may not necessarily translate to clinically relevant allergens. Nevertheless, in this study, we have managed to demonstrate that it is possible to produce synthetic drug-like molecules based on a parasitic worm product that show therapeutic potential with respect to asthma resulting from known triggers in humans.

The intergenic transcribed spacer region 1 as a molecular marker for identification and discrimination of Enterobacteriaceae associated with acute oak decline

AIMS

We assessed the veracity of intergenic spacer region 1 (ITS1) ribotyping for the rapid, inexpensive and accurate identification of Brenneria goodwinii and Gibbsiella quercinecans that are associated with acute oak decline (AOD) in the UK.

METHODS AND RESULTS

Agarose gel electrophoresis and polyacrylamide gel electrophoresis (PAGE) were applied for the typing of ITS1 PCR amplicons from strains of B. goodwinii, G. quercinecans and related species (n = 34). The number and length of ITS1 amplicons varied significantly between strains. ITS1 profiles generated via PAGE were used to differentiate species using a neighbour-joining phylogram. The ITS1 phylogram was compared against DNA gyrase B (gyrB) gene sequences from the same strains, demonstrating that ITS1 ribotyping is as effective as gyrB at resolving G. quercinecans and B. goodwinii to the species level.

CONCLUSIONS

The ITS1 gene has been successfully employed as a novel marker to resolve newly described AOD-associated Enterobacteriaceae, B. goodwinii and G. quercinecans, to species level.

SIGNIFICANCE AND IMPACT OF THE STUDY

ITS1 ribotyping of B. goodwinii and G. quercinecans provides equivalent sensitivity to the current standard method for strain identification (sequence analysis of the gyrB gene), but with reduced processing time and cost. Furthermore, the ITS1 gene is widely applicable as a rapid and inexpensive typing system for Enterobacteriaceae.

P34(cdc2) kinase is associated with cortical microtubules from higher plant protoplasts

The cell cycle regulatory enzyme p34(cdc2) kinase is known to be localized to the preprophase band, the spindle and the phragmoplast, but not to interphase cortical microtubules. This was investigated further by mechanically cleaving substrate-attached protoplasts to leave plasma membrane disks bearing microtubules freed of nuclear and cytosolic signal. Antibodies to PSTAIRE and to specific C-terminal peptides of cdc2a, were used in immunofluorescence, protein blotting and immunogold electron microscopy to demonstrate that antigen is located on the cortical microtubules of carrot, tobacco BY-2 and Arabidopsis cells.

Characterization of the ethanol-inducible alc gene-expression system in Arabidopsis thaliana

Controlled expression of transgenes in plants is key to the characterization of gene function and the regulated manipulation of growth and development. The alc gene-expression system, derived from the filamentous fungus Aspergillus nidulans, has previously been used successfully in both tobacco and potato, and has potential for use in agriculture. Its value to fundamental research is largely dependent on its utility in Arabidopsis thaliana. We have undertaken a detailed function analysis of the alc regulon in A. thaliana. By linking the alcA promoter to beta-glucuronidase (GUS), luciferase (LUC) and green fluorescent protein (GFP) genes, we demonstrate that alcR-mediated expression occurs throughout the plant in a highly responsive manner. Induction occurs within one hour and is dose-dependent, with negligible activity in the absence of the exogenous inducer for soil-grown plants. Direct application of ethanol or exposure of whole plants to ethanol vapour are equally effective means of induction. Maximal expression using soil-grown plants occurred after 5 days of induction. In the majority of transgenics, expression is tightly regulated and reversible. We describe optimal strategies for utilizing the alc system in A. thaliana.

Dynamic recruitment of Cdc2 to specific microtubule structures during mitosis

A-type cyclin-dependent kinases (CDKs), also known as cdc2, are central to the orderly progression of the cell cycle. We made a functional Green Fluorescent Protein (GFP) fusion with CDK-A (Cdc2-GFP) and followed its subcellular localization during the cell cycle in tobacco cells. During interphase, the Cdc2-GFP fusion protein was found in both the cytoplasm and the nucleus, where it was highly resistant to extraction. In premitotic cells, a bright and narrow equatorial band appeared on the cell surface, resembling the late preprophase band, which disintegrated within 10 min as followed by time-lapse images. Cdc2-GFP was not found on prophase spindles but left the chromatin soon after this stage and associated progressively with the metaphase spindle in a microtubule-dependent manner. Arresting cells in mitosis through the stabilization of microtubules by taxol further enhanced the spindle-localized pool of Cdc2-GFP. Toward the end of mitosis, Cdc2-GFP was found at the midzone of the anaphase spindle and phragmoplast; eventually, it became focused at the midline of these microtubule structures. In detergent-extracted cells, the Cdc2-GFP remained associated with mitotic structures. Retention on spindles was prevented by pretreatment with the CDK-specific inhibitor roscovitine and was enhanced by the protein phosphatase inhibitor okadaic acid. Furthermore, we demonstrate that both the endogenous CDK-A and Cdc2-GFP were cosedimented with taxol-stabilized plant microtubules from cell extracts and that Cdc2 activity was detected together with a fraction of polymerized tubulin. These data provide evidence that the A-type CDKs associate physically with mitotic structures in a microtubule-dependent manner and may be involved in regulating the behavior of specific microtubule arrays throughout mitosis.

Dynamic recruitment of Cdc2 to specific microtubule structures during mitosis

A-type cyclin-dependent kinases (CDKs), also known as cdc2, are central to the orderly progression of the cell cycle. We made a functional Green Fluorescent Protein (GFP) fusion with CDK-A (Cdc2-GFP) and followed its subcellular localization during the cell cycle in tobacco cells. During interphase, the Cdc2-GFP fusion protein was found in both the cytoplasm and the nucleus, where it was highly resistant to extraction. In premitotic cells, a bright and narrow equatorial band appeared on the cell surface, resembling the late preprophase band, which disintegrated within 10 min as followed by time-lapse images. Cdc2-GFP was not found on prophase spindles but left the chromatin soon after this stage and associated progressively with the metaphase spindle in a microtubule-dependent manner. Arresting cells in mitosis through the stabilization of microtubules by taxol further enhanced the spindle-localized pool of Cdc2-GFP. Toward the end of mitosis, Cdc2-GFP was found at the midzone of the anaphase spindle and phragmoplast; eventually, it became focused at the midline of these microtubule structures. In detergent-extracted cells, the Cdc2-GFP remained associated with mitotic structures. Retention on spindles was prevented by pretreatment with the CDK-specific inhibitor roscovitine and was enhanced by the protein phosphatase inhibitor okadaic acid. Furthermore, we demonstrate that both the endogenous CDK-A and Cdc2-GFP were cosedimented with taxol-stabilized plant microtubules from cell extracts and that Cdc2 activity was detected together with a fraction of polymerized tubulin. These data provide evidence that the A-type CDKs associate physically with mitotic structures in a microtubule-dependent manner and may be involved in regulating the behavior of specific microtubule arrays throughout mitosis.

Two kinesin-related proteins associated with the cold-stable cytoskeleton of carrot cells: characterization of a novel kinesin, DcKRP120-2

We have previously described the biochemical isolation of 65 kDa and 120 kDa microtubule-associated proteins from carrot cytoskeletons. The 65 kDa MAPs have subsequently been shown to be structural MAPs that reconstitute 30 nm cross-bridges of the kind that maintain cortical microtubules in parallel groups. By exploiting its avid binding to microtubules, we have now devised a method for isolating MAP120 from protoplast extracts, and shown that it has properties of a kinesin-related protein. MAP120 segregates with the cold stable pool of microtubules in carrot cytoskeletons, whilst the 65 kDa MAPs are also associated with the cold-sensitive microtubules. On gradient gels, MAP120 resolves as two kinesin-like bands. We report the isolation of a carrot cDNA, DcKRP120-2, corresponding to a novel kinesin of the BimC class known to move to the plus ends of microtubules. Antibodies raised against specific expressed sequences recognize the upper band, while the lower band is recognized by antibodies to the tobacco kinesin-related protein, TKRP125. We have also isolated a partial genomic carrot DNA, DcKRP120-1, homologous to the motor region of tobacco TKRP125. Immunofluorescence of the two proteins produces different staining patterns. Anti-TKRP125 labels the cortical microtubules and the pre-prophase band, but anti-DcKRP120-2 does so only weakly. Both clearly stain the spindle and the phragmoplast, but in a proportion of cells anti-DcKRP120-2 strongly decorates the phragmoplast mid-line where the plus ends of the microtubules overlap. We discuss the potential roles of these proteins during the microtubule cycle.

Social controls on cell proliferation in plants

Plant cell division occurs mainly in developing tissues and appears to be highly regulated in both space and time. Recently, genetic and molecular analyses have been able to dissect the function of cell proliferation in the processes of growth and development. Mutant studies have shown that plants have a compensatory mechanism whereby increased cell expansion can partially cover for defects in proliferation. Ectopic expression of developmental and cell-cycle regulators has indicated how growth rate is controlled at the molecular level in meristems and lateral organs.

Acute neurologic deterioration following lumbar puncture in an epidural abscess occurring 14 months after epidural catheter placement

We report the case of a 19-year-old girl admitted to the hospital with a 2-month history of back pain and a 1-week history of severe weakness, who underwent a diagnostic lumbar puncture which was swiftly followed by acute neurologic deterioration requiring ventilation. She was subsequently shown to have an epidural abscess extending from the second cervical to the fifth lumbar vertebrae. She had received uneventful epidural analgesia for childbirth 14 months previously. The case is unusual in both the acute deterioration following lumbar puncture, and also in the length of time from epidural siting to abscess formation, if this were indeed the source of the infection.

Conserved and novel regulators of the plant cell cycle

Cell division is highly regulated, both spatially and temporally, during plant development. Recent evidence implicates cyclin-dependent kinases (cdks) and their associated proteins as the principal temporal regulators of cell division. It is now known that plants contain an extended family of cdks, some of which appear to be unique to this group. Positive rate-limiting regulators of cell proliferation and growth include mitotic or B-type cyclins whose transcription is restricted to the G2 and M phases. Current research suggests that MYB-related transcription factors may be responsible for this restriction. Cdk-interacting proteins, such as cdk inhibitors and suc1 homologues, have been isolated using yeast two-hybrid approaches.

Plant growth: roots in the cell cycle

Overexpression in transgenic plants of a B-type cyclin--thought to regulate cell-cycle progression to mitosis--causes structures such as roots to grow faster than normal, indicating that the rate of cell division may be a constraint on plant growth.

Cloning and characterization of a dihydrolipoamide acetyltransferase (E2) subunit of the pyruvate dehydrogenase complex from Arabidopsis thaliana

A cDNA encoding a dihydrolipoamide acetyltransferase (E2) subunit of the pyruvate dehydrogenase complex has been isolated from Arabidopsis thaliana. A cell culture cDNA expression library was screened with a monoclonal antibody (JIM 63) raised against nuclear matrix proteins, and four clones were isolated. One of these was 2175 base pairs in length, and it contained an open reading frame with an amino acid sequence and domain structure with strong similarity to the E2s of other eukaryotic and prokaryotic organisms. The organization and number of functional domains within the Arabidopsis protein are identical to those of the human E2, although the amino acid sequences within these domains are equally similar to those of the yeast and human proteins. The predicted amino acid sequence reveals the presence of a putative amino-terminal leader sequence with characteristics similar to those of other proteins, which are targeted to the plant mitochondrial matrix. The cross-reactivities of plant mitochondrial matrix proteins with JIM 63 and antibodies raised against the E2 and protein X components of eukaryotic pyruvate dehydrogenase complexes are consistent with the clone encoding a mitochondrial form of E2 and not the smaller protein X. The E2 mRNA of 2.2 kilobases was expressed in a range of Arabidopsis and Brassica napus tissues.

Cell division in plants

The past couple of years have seen the isolation and characterization of many of the regulatory genes from plants that are thought to be intimately involved in regulation of the cell division cycle. In addition, characterization of plant-specific aspects of the cell division cycle has provided insight into how spatial and temporal controls may be linked. The comparative lack of cell mobility means that plant organs are historic records of the cell cycles that occurred during their evolution. Differentiated cells retain a capacity for re-entry into the cell cycle, which is probably an adaptation to compensate for the damage that they must tolerate because of a sedentary lifestyle. Understanding how plants cope with such damage and manage to generate such an array of diverse multicellular structures will require a basic comprehension of cell division.