Plasma cells require autophagy for sustainable immunoglobulin production.

The role of autophagy in plasma cells is unknown. Here we found notable autophagic activity in both differentiating and long-lived plasma cells and investigated its function through the use of mice with conditional deficiency in the essential autophagic molecule Atg5 in B cells. Atg5(-/-) differentiating plasma cells had a larger endoplasmic reticulum (ER) and more ER stress signaling than did their wild-type counterparts, which led to higher expression of the transcriptional repressor Blimp-1 and immunoglobulins and more antibody secretion. The enhanced immunoglobulin synthesis was associated with less intracellular ATP and more death of mutant plasma cells, which identified an unsuspected autophagy-dependent cytoprotective trade-off between immunoglobulin synthesis and viability. In vivo, mice with conditional deficiency in Atg5 in B cells had defective antibody responses, complete selection in the bone marrow for plasma cells that escaped Atg5 deletion and fewer antigen-specific long-lived bone marrow plasma cells than did wild-type mice, despite having normal germinal center responses. Thus, autophagy is specifically required for plasma cell homeostasis and long-lived humoral immunity.

Extreme hydrothermal conditions at an active plate-bounding fault.

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Compliance and satisfaction with intensive physiotherapy treatment during chemotherapy in patients with bone tumours and evaluation of related prognostic factors: An observational study.

The purpose of this study was to evaluate compliance and satisfaction of adult patients to intensive rehabilitation treatment during chemotherapy cycles after surgery for bone-musculoskeletal tumours, as well as to identify possible predictive factors. An observational, prognostic, prospective study was conducted. The study enrolled 27 patients who previously had undergone modular knee prosthesis surgery in the period between October 2014 and October 2015. The outcome was compliance to intensive rehabilitation treatment during hospitalisations in the chemotherapy unit and patient satisfaction 6 months' post-surgery. The variables taken into account were linked to the patient's characteristics, to the oncological pathology and to the chemotherapy treatment administered. Patients' compliance was 100% (range, 61-100). The presence of surgery complications (29.6%) produced 5% loss in compliance to treatment; likewise, chemotherapy treatment with prevalent use of ifosfamide reduced compliance to rehabilitation by 6%. The mean patient satisfaction score was 7.9 in the Likert scale from 0 to 10. Intensive physiotherapy starting during chemotherapy administration is a feasible treatment for bone tumour patients that have shown to be able to positively adhere to it. Rehabilitation treatments, within chemotherapy wards, should therefore be promoted according to satisfaction level as reported by patient.

The Videoinsight® Method: improving early results following total knee arthroplasty.

PURPOSE: The purpose of this randomized double-blind study was to investigate the effectiveness of the Videoinsight® psychological enhancing method in promoting early recovery during rehabilitation following total knee arthroplasty. METHODS: One-hundred and ten patients treated with cemented total knee arthroplasty were randomly assigned to Group A or Group B, and both groups underwent the same rehabilitation programme. Group A (55 patients) received one art video selected according to Videoinsight® concept. This art video promoting self-confidence and psychological support to the patient has been shown in the physical therapy department before any rehabilitation session, in the first 15 days after surgery and then three times a week for the next 4 weeks. Group B (55 patients) underwent the same rehabilitation protocol in the same setting, after TKA surgery, without the video support. Patients were evaluated pre-operatively and 3 months after surgery with Physical and Mental SF-36, State-Trait Anxiety Inventory (STAI), Beck Depression Inventory (BDI), Tampa Scale of Kinesiophobia (TSK), Knee Society Score (KSS), VAS, and WOMAC scores. RESULTS: Eight patients were lost to follow-up, and 102 patients (Group A: 52 patients; Group B: 50 patients) were available at mean 3.0 ± 0.2 months follow-up. Age at surgery was 69.1 ± 13.0 years. The two groups were homogeneous regarding pre-operative demographic data and clinical outcomes. Significant improvements were observed in both groups compared to baseline and in Group A compared to Group B at final follow-up for functional and psychological scores except for SF-36. Respectively, Group A and Group B showed WOMAC 79.9 ± 13.0 and 69.7 ± 9.5 (p < 0.005), VAS 2.8 ± 1.6 and 4.0 ± 1.5, (p < 0.005), KSS 87.8 ± 9.6 and 78.3 ± 8.2 (p < 0.005), BDI 5.1 ± 4.8 and 9.4 ± 3.9 (p < 0.005), STAI 30.8 ± 7.9 and 34.8 ± 7.8 (p < 0.005), and TSK 24.4 ± 5.5 and 29.3 ± 4.8 (p < 0.005). CONCLUSION: The Videoinsight(®) psychological enhancing method, by the view of video art images, combined to an adequate rehabilitation protocol can be a means for further improving short-term clinical and functional outcomes by giving a psychological support to patients who underwent total knee arthroplasty. LEVEL OF EVIDENCE: I.

How Much Clinical and Functional Impairment do Children Treated With Knee Rotationplasty Experience in Adulthood?

BACKGROUND: Rotationplasty may be indicated for some children with osteosarcoma in the distal femur or proximal tibia; in properly selected patients, it may offer functional advantages over transfemoral amputation and more durable results than a prosthesis. The clinical and functional outcomes reported for this procedure generally have been limited to studies with a mean followup of approximately 8 years in terms of Musculoskeletal Tumor Society Score (MSTS), physical examination, and gait analysis. However, the effects of residual thigh-shank length on gait have not been explored to our knowledge. QUESTIONS/PURPOSES: We asked: (1) Do differences in the length of the surgically treated residual thigh-shank relative to the contralateral thigh result in altered gait patterns? (2) What were the clinical and functional impairments and radiographic findings of patients who underwent rotationplasty and who survived to adulthood? (3) Do gait analysis findings in adults differ from previously reported findings in children in terms of relevant gait parameters such as maximal ground reaction forces and sagittal knee angles? METHODS: From January 1986 to December 2009, 254 children (age range, 3-14 years) affected by high-grade bone sarcomas located in the distal half of the femur were surgically treated at our institute. Forty-two of these patients (16.5%) underwent rotationplasty. During this period, three adolescents older than 15 years were treated by rotationplasty owing to the tumor volume and extracompartmental involvement. In total, 45 patients underwent rotationplasty. From January 1986 to December 2000, rotationplasty generally was the preferred treatment for patients younger than 9 years with a high-grade bone sarcoma calling for an intra- or extraarticular resection of the distal femur, as long as the sciatic nerve could be spared. From January 2001, the procedure was not used as often. Of the 45 patients who underwent a rotationplasty, 14 died of disease at a mean of 37 months (31%); 31 patients (69%) were survivors at the time the study was done, 29 of whom were continuously disease free (64%) and two had no evidence of disease after a pulmonary metastasectomy (5%). These 31 patients were invited to participate in the study, and 25 of the 31 agreed to participate. There were 15 males and 10 females with a mean age of 23.8 years (SD, 7.5 years) and mean followup of 15 years (SD, 5.8 years). Clinical assessment included the MSTS score (total score ranges between 0 and 30 with 0 indicating poor results and 30 indicating good results), obtained by clinical assessment and patient interview, measurements of the residual thigh-shank length and of the contralateral thigh, of the lengths of the surgically treated and contralateral feet, and of active ROM of the rotated and contralateral ankles. Of the 25 patients, 22 (88%) agreed to have lower limb radiographs and 16 (64%) agreed to perform gait analysis. RESULTS: The residual thigh-shank was, on average, 5.8% longer than the contralateral thigh. Differences in the length of the residual thigh-shank relative to the contralateral thigh resulted in altered gait patterns. Patients with longer residual thigh-shank length had greater pseudoknee flexion during stance and swing. Patients with shorter residual thigh-shank length walked with a gait similar to that of controls. The mean MSTS score was 25 (SD, 2). With respect to the contralateral foot, the surgically treated foot was 10% shorter, the talus 11% shorter in the long axis and 7.6% in the short axis and the calcaneus was 2.7% shorter in the long axis and 8.6% in the short axis. Radiologic arthritis was present in most patients at the tibiotalar, subtalar, and talonavicular joints. As adults, our patients showed improved gait parameters compared with previously reported findings for children undergoing rotationplasty. Vertical ground reaction force during midstance was reduced by 6% and knee ROM during the gait cycle was increased by 24.6°. CONCLUSIONS: The residual thigh-shank length influences the gait performance, such that patients with smaller discrepancies between the surgically treated and contralateral sides had the best walking performance. The MSTS score at a mean of 15 years after knee rotationplasty confirmed the results reported in the shorter-term for function and pain. The foot on the surgically treated side was smaller than the contralateral foot, and degenerative changes were present, which could contribute to impaired function. Gait performance, in terms of ground reaction forces and knee ROM, was improved in our adult patients although a difference in loading was still present between the surgically treated and contralateral limbs. Based on these findings, surgeons should endeavor to have the center axis of rotation of the contralateral knee and pseudoknee at skeletal maturity. An excessive residual thigh-shank length in adult patients could require contralateral lengthening to improve functional results. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Assessing Heterogeneity of Osteolytic Lesions in Multiple Myeloma by ¹H HR-MAS NMR Metabolomics.

Multiple myeloma (MM) is a malignancy of plasma cells characterized by multifocal osteolytic bone lesions. Macroscopic and genetic heterogeneity has been documented within MM lesions. Understanding the bases of such heterogeneity may unveil relevant features of MM pathobiology. To this aim, we deployed unbiased ¹H high-resolution magic-angle spinning (HR-MAS) nuclear magnetic resonance (NMR) metabolomics to analyze multiple biopsy specimens of osteolytic lesions from one case of pathological fracture caused by MM. Multivariate analyses on normalized metabolite peak integrals allowed clusterization of samples in accordance with a posteriori histological findings. We investigated the relationship between morphological and NMR features by merging morphological data and metabolite profiling into a single correlation matrix. Data-merging addressed tissue heterogeneity, and greatly facilitated the mapping of lesions and nearby healthy tissues. Our proof-of-principle study reveals integrated metabolomics and histomorphology as a promising approach for the targeted study of osteolytic lesions.

Gene therapy augments the efficacy of hematopoietic cell transplantation and fully corrects mucopolysaccharidosis type I phenotype in the mouse model.

Type I mucopolysaccharidosis (MPS I) is a lysosomal storage disorder caused by the deficiency of α-L-iduronidase, which results in glycosaminoglycan accumulation in tissues. Clinical manifestations include skeletal dysplasia, joint stiffness, visual and auditory defects, cardiac insufficiency, hepatosplenomegaly, and mental retardation (the last being present exclusively in the severe Hurler variant). The available treatments, enzyme-replacement therapy and hematopoietic stem cell (HSC) transplantation, can ameliorate most disease manifestations, but their outcome on skeletal and brain disease could be further improved. We demonstrate here that HSC gene therapy, based on lentiviral vectors, completely corrects disease manifestations in the mouse model. Of note, the therapeutic benefit provided by gene therapy on critical MPS I manifestations, such as neurologic and skeletal disease, greatly exceeds that exerted by HSC transplantation, the standard of care treatment for Hurler patients. Interestingly, therapeutic efficacy of HSC gene therapy is strictly dependent on the achievement of supranormal enzyme activity in the hematopoietic system of transplanted mice, which allows enzyme delivery to the brain and skeleton for disease correction. Overall, our data provide evidence of an efficacious treatment for MPS I Hurler patients, warranting future development toward clinical testing.

Do chronic pain syndromes in lower limb amputees have an effect on the use of prostheses?

BACKGROUND: The use of a prosthesis is critical to regain the ability to walk in lower limb amputees but the relationship between the use of a prosthesis and chronic pain syndromes (PLS, PLP, RLP), common in amputees patients, is still poorly understood. OBJECTIVE: This long-term follow-up study investigates the possible correlation between prosthesis use and the presence of PLP, PLS and RLP in lower limb amputees. METHODS: Patients undergoing transtibial, transfemoral or hemipelvectomy amputation of any aetiology at the Rizzoli Orthopaedic Institute from 2008 to 2018 were included. The Houghton scale was used to assess functional use of the prosthesis. The PEQ was used for pain assessment. RESULTS: The results show that, in lower limb amputees, prosthesis use is greater in individuals with below-the-knee amputation and in those who were younger at the time of amputation. No significant correlation between the presence of pain syndromes (PLS, PLP, RLP) and the various items on the Houghton scale was found. CONCLUSIONS: The study found no significant correlation indicating that phantom limb pain syndromes affect amputee use of a prosthesis in the long term follow up.

Band Structure Engineering of Bi4O4SeCl2 for Thermoelectric Applications.

The mixed anion material Bi4O4SeCl2 has an ultralow thermal conductivity of 0.1 W m-1 K-1 along its stacking axis (c axis) at room temperature, which makes it an ideal candidate for electronic band structure optimization via doping to improve its thermoelectric performance. Here, we design and realize an optimal doping strategy for Bi4O4SeCl2 from first principles and predict an enhancement in the density of states at the Fermi level of the material upon Sn and Ge doping. Experimental work realizes the as-predicted behavior in Bi4-x Sn x O4SeCl2 (x = 0.01) through the precise control of composition. Careful consideration of multiple accessible dopant sites and charge states allows for the effective computational screening of dopants for thermoelectric properties in Bi4O4SeCl2 and may be a suitable route for assessing other candidate materials.

Abductor muscle strengthening in THA patients operated with minimally-invasive anterolateral approach for developmental hip dysplasia.

OBJECTIVE: In developmental hip dysplasia (DDH) patients, the chronic dislocation of the femoral head with respect to the true acetabulum determines muscle contracture and atrophy, particularly of the abductor muscles, and leads to secondary osteoarthritis (OA) with severe motor dysfunction, pain and disability. The correct positioning when a total hip replacement (THR) is performed is fundamental to the recovery of gait function. Also, inadequate rehabilitation of the abductor muscles for pelvic stabilisation can be responsible for residual dysfunction. Consensus on a programme for abductor muscle strengthening in these patients is not currently available. The aim of this study was to evaluate the effectiveness of a specific program of exercises for strengthening the abductor muscles in these patients. METHODS: A multicentre, prospective, randomised clinical trial was carried out in an outpatient rehabilitation setting on 103 patients given THR for DDH through a minimally-invasive anterolateral approach. Patients were randomly divided into a Study Group, including 46 patients, and a Control Group, including 57 patients. All patients underwent standard early postoperative rehabilitation. In addition, the Study Group were given an extra 2-week rehabilitation once full weight-bearing on the operated limb was allowed, aimed at strengthening the abductor muscles. All patients were evaluated preoperatively, and at about 3 and 6 months postoperatively. Clinical measures (lower limb-length differences, hip range of motion, abductor muscle strength), and functional measures (WOMAC, HHS, 10mt WT, SF-12) were taken. RESULTS: Hip range of motion and functional outcome measures showed a progressive improvement at follow ups in both groups, significantly higher in the Study Group. In particular, abductor strength at 6 months post-op improved by 92.5% with respect to 35.7% in the Control Group. CONCLUSION: In addition to standard rehabilitation, a rehabilitation programme for strengthening the gluteal muscles in DDH patients who underwent THR determined an increase in muscle strength that improved functional performance and patient satisfaction.

Cross-Cultural Validation of the Italian Version of the Bt-DUX: A Subjective Measure of Health-Related Quality of Life in Patients Who Underwent Surgery for Lower Extremity Malignant Bone Tumour.

The purpose of this study was to translate the English bone tumour DUX (Bt-DUX-Eng) questionnaire for lower extremity bone tumour patients, a disease-specific quality of life (QoL) instrument, into Italian and then examine the validity of the Italian version of Bt-DUX (Bt-DUX-It). The adaptation and translation process included forward translation, back-translation, and a review of the back-translation by an expert committee. The Bt-DUX-It was validated in a sample of adolescents treated for lower extremity osteosarcoma in Italy. Assessments included the Bt-DUX, the Toronto Extremity Salvage Score (TESS), and the European Organization for Research and Treatment Core Quality of Life Questionnaire of Cancer Patients (EORTC QLQ-C30). Fifty-one patients with a median age of 20 years (range: 15-25) completed the questionnaires. The mean Bt-DUX score was 70 (range: 16.30-100). The internal consistency of the overall score and that of the Bt-DUX-It was good: Cronbach's α was 0.95. Spearman's correlation coefficient between the Bt-DUX (total and domain scores) and EORTC QLQ C30 and TESS were overall moderate to good, reaching a p-value <0.01 in all cases. The Bt-DUX-It version is a useful tool for measuring QoL in patients with bone tumour and has similar internal consistency, construct validity, and discrimination as those of the Dutch and English versions.

Magnesium-enriched hydroxyapatite versus autologous bone in maxillary sinus grafting: combining histomorphometry with osteoblast gene expression profiles ex vivo.

BACKGROUND: Many biomaterials are proposed for sinus floor lifting and grafting in the posterior maxilla for insufficient bone volume (BV). The aim of this study was to compare the use of magnesium-enriched hydroxyapatite (mHA) versus autogenous bone graft (AB) for maxillary sinus lift procedures by histomorphometric and ex vivo gene expression profiling. METHODS: Fifteen patients requiring bilateral maxillary sinus augmentation received autologous bone particles (group A) and mHA (group B) (split-mouth design). Five months later, implants were placed, and biopsies were obtained. Bone specimens were analyzed by histomorphometry, BV and vital bone (VB) percentages were calculated, and ex vivo osteoblast expansion followed by highly sensitive osteoblast specific gene expression profiling for cbfa1, osteocalcin, osteopontin, collagen type I, receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoprotegerin (OPG) by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) were performed. Comparisons were made using the Student t test. RESULTS: After healing with no complications, BV was comparable in the two groups (80.79% +/- 14.27% for autologous versus 76.72% +/- 11.47% for mHA; P = not statistically significant), but VB was lower in the mHA group (29.65% +/- 9.81% versus 78.40% +/- 16.72%; P <0.05). Real-time RT-PCR analyses showed significantly higher expression of the osteoblast differentiation factor Cbfa1 and the matrix formation marker osteocalcin in the mHA group compared to the AB group, whereas type I collagen was comparable, and osteopontin was decreased. Attesting to a lower osteoclastogenic potential, the RANKL/OPG ratio was diminished. CONCLUSIONS: Autogenous bone samples provided higher vital over comparable total bone levels than mHA-grafted sites. Osteoblast gene expression profiles from mHA grafts revealed higher expression of certain specific markers of osteoblast differentiation and bone formation, associated with a lower osteoclastogenic potential.

Ripplocations provide a new mechanism for the deformation of phyllosilicates in the lithosphere.

Deformation in Earth's lithosphere is localised in narrow, high-strain zones. Phyllosilicates, strongly anisotropic layered minerals, are abundant in these rocks, where they accommodate much of the strain and play a significant role in inhibiting or triggering earthquakes. Until now it was understood that phyllosilicates could deform only by dislocation glide along layers and could not accommodate large strains without cracking and dilation. Here we show that a new class of atomic-scale defects, known as ripplocations, explain the development of layer-normal strain without brittle damage. We use high-resolution transmission electron microscopy (TEM) to resolve nano-scale bending characteristic of ripplocations in the phyllosilicate mineral biotite. We demonstrate that conjugate delamination arrays are the result of elastic strain energy release due to the accumulation of layer-normal strain in ripplocations. This work provides the missing mechanism necessary to understand phyllosilicate deformation, with important rheological implications for phyllosilicate bearing seismogenic faults and subduction zones.

Which factors are associated with the functional recovery in patients undergoing endoprosthetic knee reconstruction following bone tumour resection? - A observational study.

BACKGROUND: The aim of the present study was to explore whether control of balance and other factors were associated with functional recovery and walking performance in the short term in a group of patients receiving modular knee endoprosthetic reconstruction following bone tumour resection in order to provide effective suggestions for a new rehabilitation protocol. METHODS: A cross-sectional study was carried out in the chemotherapy ward of an Italian hospital specialized in bone cancer. All patients consecutively treated using a modular knee endoprosthetic between January 2013 and February 2014 were included in the study. One year after surgery, various measuring instruments were used to assess the functional outcome achieved: Musculoskeletal Tumor Society rating scale, Toronto Extremity Salvage Score and specific motor tests of gait, such as gait speed and resistance. Data concerning the variables involved are as follows: bone resection, knee joint range of motion, quadriceps muscle strength and posture control. Statistical tests included correlation analysis (Pearson and Spearman correlation). RESULTS: Balance control was significantly correlated to all the gait tests performed. Age, duration of chemotherapy and strength of the knee extensor muscles also showed a correlation. Conversely, joint range of motion and resection percentage did not show a significant correlation. CONCLUSIONS: Rehabilitation in patients undergoing knee joint reconstruction due to cancer should include balance control exercises, which involve not only the treated limb but address the entire sensory and motor system. This extends beyond the concept of treatment aimed at improving individual functions such as joint range of motion and muscular strength.

Localized muscle vibration reverses quadriceps muscle hypotrophy and improves physical function: a clinical and electrophysiological study.

Quadriceps weakness has been associated with knee osteoarthritis (OA). High-frequency localized muscle vibration (LMV) has been proposed recently for quadriceps strengthening in patients with knee OA. The purpose of this study was (a) to investigate the clinical effectiveness of high-frequency LMV on quadriceps muscle in patients with knee OA and (b) to disentangle, by means of surface electromyography (sEMG), the underlying mechanism. Thirty patients, aged between 40 and 65 years, and clinically diagnosed with knee OA were included in this randomized, controlled, single-blinded pilot study. Participants were randomly assigned to two groups: a study group treated with LMV, specifically set for muscle strengthening (150 Hz), by means of a commercial device VIBRA, and a control group treated with neuromuscular electrical stimulation. Clinical outcome was measured using the Western Ontario and McMaster Universities Osteoarthritis Index, Visual Analogue Scale, knee range of motion, Timed Up and Go test, and Stair climbing test. To assess changes in muscle activation and fatigue a subgroup of 20 patients was studied with the use of sEMG during a sustained isometric contraction. The LMV group showed a significant change in Western Ontario and McMaster Universities Osteoarthritis Index score, Visual Analogue Scale score, Timed Up and Go test, Stair Climbing Test, and knee flexion. These improvements were not significant in patients treated with neuromuscular electrical stimulation. sEMG analysis suggested an increased involvement of type II muscle fibers in the group treated with LMV. In conclusion, the present study supports the effectiveness of local vibration in muscle function and clinical improvement of patients with knee OA.

Muscle inflammation and MHC class I up-regulation in muscular dystrophy with lack of dysferlin: an immunopathological study.

Muscle inflammation is characteristic of inflammatory myopathies but also occurs in muscular dystrophy with lack of the sarcolemmal protein dysferlin. We quantified inflammatory cells and major histocompatibility complex (MHC) expression in muscle from 10 patients with dysferlinopathy. Infiltrating cells were always present although numbers varied considerably; macrophages were more common than T cells, T cytotoxicity was absent, and MHC class I was overexpressed on muscle fibers. These findings differ from polymyositis (PM) but are closely similar to those in SJL/J mice (which lack dysferlin) and emphasize the relationship between absence of dysferlin and immune system abnormalities in muscle.

MHC class II transactivator is an in vivo regulator of osteoclast differentiation and bone homeostasis co-opted from adaptive immunity.

The molecular networks controlling bone homeostasis are not fully understood. The common evolution of bone and adaptive immunity encourages the investigation of shared regulatory circuits. MHC Class II Transactivator (CIITA) is a master transcriptional co-activator believed to be exclusively dedicated for antigen presentation. CIITA is expressed in osteoclast precursors, and its expression is accentuated in osteoporotic mice. We thus asked whether CIITA plays a role in bone biology. To this aim, we fully characterized the bone phenotype of two mouse models of CIITA overexpression, respectively systemic and restricted to the monocyte-osteoclast lineage. Both CIITA-overexpressing mouse models revealed severe spontaneous osteoporosis, as assessed by micro-computed tomography and histomorphometry, associated with increased osteoclast numbers and enhanced in vivo bone resorption, whereas osteoblast numbers and in vivo bone-forming activity were unaffected. To understand the underlying cellular and molecular bases, we investigated ex vivo the differentiation of mutant bone marrow monocytes into osteoclasts and immune effectors, as well as osteoclastogenic signaling pathways. CIITA-overexpressing monocytes differentiated normally into effector macrophages or dendritic cells but showed enhanced osteoclastogenesis, whereas CIITA ablation suppressed osteoclast differentiation. Increased c-fms and receptor activator of NF-κB (RANK) signaling underlay enhanced osteoclast differentiation from CIITA-overexpressing precursors. Moreover, by extending selected phenotypic and cellular analyses to additional genetic mouse models, namely MHC Class II deficient mice and a transgenic mouse line lacking a specific CIITA promoter and re-expressing CIITA in the thymus, we excluded MHC Class II expression and T cells from contributing to the observed skeletal phenotype. Altogether, our study provides compelling genetic evidence that CIITA, the molecular switch of antigen presentation, plays a novel, unexpected function in skeletal homeostasis, independent of MHC Class II expression and T cells, by exerting a selective and intrinsic control of osteoclast differentiation and bone resorption in vivo.

Corticocancellous porcine bone in the healing of human extraction sockets: combining histomorphometry with osteoblast gene expression profiles in vivo.

PURPOSE: Different graft materials have been proposed to minimize the collapse of alveolar bone after tooth extraction. The aim of this study was to examine the use of porcine bone graft in fresh sockets via histomorphometric and in vivo gene expression profiling. MATERIALS AND METHODS: Thirty fresh extraction sockets with three bone walls in 15 patients were selected. A split-mouth design was employed. On one side of the arch, 15 sockets received corticocancellous porcine bone as a graft, and on the other side, 15 sockets were left unfilled and considered as controls. Four months after surgery, four biopsy specimens were taken from each patient (two from the grafted site and two from the control site). The specimens were analyzed by histomorphometry and ex vivo osteoblast expansion, followed by highly sensitive osteoblast-specific gene expression profiling for Runx2, osteopontin, osteoprotegerin, type I collagen, and alkaline phosphatase by quantitative real-time reverse-transcriptase polymerase chain reaction. Comparisons were made using the Student t test. RESULTS: After healing without complications, the grafted sites showed statistically significantly higher mean vital bone and lower mean connective tissue values than the control sites. Statistically significant higher expression of alkaline phosphatase and the matrix formation markers type I collagen and osteopontin were observed in the grafted group compared to the control group, whereas Runx2 and osteoprotegerin expression was comparable. CONCLUSIONS: Within the limits of this study, histologic examination and biomolecular evaluation confirmed good biocompatibility and high osteoconductivity of xenogeneic porcine bone in alveolar bone grafting.

Dampening Ab responses using proteasome inhibitors following in vivo B cell activation.

Upon encounter with Ag, B lymphocytes undergo terminal differentiation into plasma cells, highly specialized Ab secretors that mediate humoral immune responses. Profound changes adapt cellular morphology and proteome to the new secretory functions. Although a massive secretory activity is expected to require an efficient ubiquitin-proteasome degradation system, recent in vitro studies have surprisingly revealed that the proteasome function sharply decreases during plasma cell development, thereby limiting the proteolytic capacity. We challenged this paradigm in mouse models of B cell activation, and observed that following polyclonal activation, proteasome activity decreases more than previously reported in vitro. This decrease is linked to enhanced apoptosis after treatment with the potent anti-myeloma proteasome inhibitor PS-341. Accordingly, in vivo treatment with PS-341 decreases Ab titres in T-dependent and -independent mouse immunization models. This study provides the rationale for limiting the activity of Ab-secreting cells in vivo by impacting proteasome function.