Elevation of neutrophil-derived factors in patients after multiple trauma.

Trauma represents one of the leading causes of death worldwide. Traumatic injuries elicit a dynamic inflammatory response with systemic release of inflammatory cytokines. Disbalance of this response can lead to systemic inflammatory response syndrome or compensatory anti-inflammatory response syndrome. As neutrophils play a major role in innate immune defence and are crucial in the injury-induced immunological response, we aimed to investigate systemic neutrophil-derived immunomodulators in trauma patients. Therefore, serum levels of neutrophil elastase (NE), myeloperoxidase (MPO) and citrullinated histone H3 (CitH3) were quantified in patients with injury severity scores above 15. Additionally, leukocyte, platelet, fibrinogen and CRP levels were assessed. Lastly, we analysed the association of neutrophil-derived factors with clinical severity scoring systems. Although the release of MPO, NE and CitH3 was not predictive of mortality, we found a remarkable increase in MPO and NE in trauma patients as compared with healthy controls. We also found significantly increased levels of MPO and NE on Days 1 and 5 after initial trauma in critically injured patients. Taken together, our data suggest a role for neutrophil activation in trauma. Targeting exacerbated neutrophil activation might represent a new therapeutic option for critically injured patients.

Spinal cord from body donors is suitable for multicolor immunofluorescence.

Immunohistochemistry is a powerful tool for studying neuronal tissue from humans at the molecular level. Obtaining fresh neuronal tissue from human organ donors is difficult and sometimes impossible. In anatomical body donations, neuronal tissue is dedicated to research purposes and because of its easier availability, it may be an alternative source for research. In this study, we harvested spinal cord from a single organ donor 2 h (h) postmortem and spinal cord from body donors 24, 48, and 72 h postmortem and tested how long after death, valid multi-color immunofluorescence or horseradish peroxidase (HRP) immunohistochemistry is possible. We used general and specific neuronal markers and glial markers for immunolabeling experiments. Here we showed that it is possible to visualize molecularly different neuronal elements with high precision in the body donor spinal cord 24 h postmortem and the quality of the image data was comparable to those from the fresh organ donor spinal cord. High-contrast multicolor images of the 24-h spinal cords allowed accurate automated quantification of different neuronal elements in the same sample. Although there was antibody-specific signal reduction over postmortem intervals, the signal quality for most antibodies was acceptable at 48 h but no longer at 72 h postmortem. In conclusion, our study has defined a postmortem time window of more than 24 h during which valid immunohistochemical information can be obtained from the body donor spinal cord. Due to the easier availability, neuronal tissue from body donors is an alternative source for basic and clinical research.

Early radiographic osseointegration of a novel highly porous 3D-printed titanium collar for megaprostheses compared to a previous generation smooth HA-coated collar.

PURPOSE: Extracortical osseointegration at the collar-bone interface of megaprostheses is associated with improved implant stability, lower rates of stem fracture and loosening. The use of hydroxy-apatite (HA-) coated collars showed mixed results in previously published reports. A novel collar system has recently become available utilizing additive manufacturing technology to create a highly porous titanium collar with a calcium-phosphate coated surface. The aim of this study was to evaluate our early experience with this novel collar and compare it to the previously used HA-coated model. METHODS: Twenty patients who underwent megaprostheses implantation utilizing the novel collar system were case matched to 20 patients who had previously undergone a HA-coated collar. A minimum radiological follow-up of three months was available in all included patients. Osseointegration was evaluated using postoperative plain radiographs in two planes based on a previously published semi-quantitative score. RESULTS: Compared to the HA-coated collar the use of the novel highly porous collar was associated with a higher proportion of cases demonstrating osseointegration at the bone-collar interface (80% vs. 65%). Application of the highly porous collar led to a significantly shortened time to reach the final ongrowth score (173 ± 89 days vs. 299 ± 165 days, p < 0.05). At one year follow-up, 90% of the novel collars had reached their final osseoingration grade compared to 50% in the HA-coated collar group (p < 0.001). Radiological osseointegration was seen in 71% for highly porous collars where the indication was revision arthroplasty, compared to 27% in reported in the literature. CONCLUSION: These results indicate more reliable and accelerated osseointegration at the bone-collar interface of a novel highly porous collar system compared to a previously used HA-coated collar. Further studies are warranted to confirm these findings.

Does the pronator-sparing approach improve functional outcome, compared to a standard volar approach, in volar plating of distal radius fractures? A prospective, randomized controlled trial.

BACKGROUND: This study aimed to compare functional outcomes of a volar plate osteosynthesis for distal radius fractures (DRF) performed with either a standard volar approach (SVA), which required detachment of the pronator quadratus muscle, or a pronator-sparing approach (PqSA). MATERIALS AND METHODS: This prospective randomized controlled study included 106 patients scheduled for volar plate osteosyntheses. Patients were allocated to either the SVA group (n = 53) or the PqSA group (n = 53). Patients were blinded to treatment until completion of the study. The primary outcome measure was the Patient-Rated Wrist Evaluation (PRWE). Secondary outcome parameters were the Disabilities of the Arm, Shoulder, and Hand (DASH) score and the Modified Mayo Wrist Score (MMWS). Follow-up examinations were performed at 8 weeks and 3, 6, and 12 months postoperatively. RESULTS: Overall, 91 patients were included in the final analysis: 48 in the SVA group and 43 in the PqSA group. The two cohorts were not significantly different in demographic characteristics, including age, sex, injuries on the dominant side, type of injury, and fracture classification. We found significant differences between groups at 6 months in the mean PRWE (SVA: 12.3 ± 10.4, PqSA: 18.9 ± 14.11 points) and in the mean DASH score (SVA: 12.3 ± 11.9, PqSA: 19.3 ± 16.7 points), which favoured the SVA. We found no significant differences between groups in the MMWS or in the PRWE and DASH scores at any other time points. CONCLUSIONS: This randomized comparative clinical trial failed to demonstrate that a volar plate osteosynthesis performed with a PqSA could improve the outcome, compared to the SVA, in patients with DRF. LEVEL OF EVIDENCE: II Trial registration Comparison of Two Volar Plating Systems for Distal Radius Fractures, ClinicalTrials.gov (NCT03474445), registered 22 March 2018, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03474445?cond=radius&cntry=AT&draw=2&rank=1.

Standard radiographic assessments of distal radius fractures miss involvement of the distal radioulnar joint: a diagnostic study.

INTRODUCTION: Distal radius fractures account for one-fifth of all fractures in the emergency department. Their classification based on standard radiographs is common practice although low inter-observer reliabilities and superiority of computer tomography (CT) scanning in evaluation of joint congruency have been reported. MATERIALS AND METHODS: We retrospectively analyzed 96 displaced distal radius fractures scheduled for open reduction and internal fixation using standard radiographic assessment. The radiographs were classified with the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA), Fernandez and Frykman classifications by three observers and inter-rater reliabilities were calculated. Additional CT scanning was performed in all cases and the following parameters were assessed: radiocarpal joint involvement, fracture extent into the radial sigmoid notch, i.e. the distal radio-ulnar joint, comminution of the metaphysis, and concomitant ulnar styloid fracture. The CT scans were used as a reference standard to determine sensitivity and accuracy of standard radiographic assessment in evaluation of distal radius fractures. RESULTS: The inter-rater agreement for the AO classification was 35.4%, 68.8% for the Fernandez and 38.5% for the Frykman classification. Fracture extension into the radiocarpal joint was present in 81 cases (84.4%). Sigmoid notch involvement was found in 81 fractures (84.4%). Involvement of both joints was present in 72 cases (75%). The sensitivity of standard radiographs regarding radiocarpal joint involvement was 93.8%. Considering involvement of the distal radio-ulnar joint the false-negative rate using standard radiographs was 61.7% and the test's accuracy for sigmoid notch involvement was 45.8%. CONCLUSION: This study demonstrates that involvement of the sigmoid notch is frequently missed in standard radiographs. The presented data support the frequent use of CT imaging to allow the holistic illustration of a fracture's complexion and to ensure optimal pre-operative planning.

Does patient positioning influence blood loss and transfusion rate in hip replacement for femoral neck fractures? A single-centre, retrospective chart review.

BACKGROUND: We compared blood loss and transfusion frequency between the lateral decubitus and the supine position in patients undergoing hip replacement surgery due to femoral neck fractures. METHODS: We retrospectively included femoral neck fracture patients treated with either hemi (HA) or total hip arthroplasty (THA). We included a total of 626 patients, of which 313 patients underwent surgery in the lateral decubitus position and 313 patients in the supine position. Preoperative and day 1 postoperative blood measures including hemoglobin (Hb), hematocrit (Hct), and red blood cell count (RBC) were evaluated, as well as transfusion records analyzed. RESULTS: The following decrease of laboratory parameters between pre- and 1st day postoperative measures was noted: RBC: -0.77 G/L (± 0.5 G/L, median = -0.80 G/L; range: -0.50 - -1.10 G/L); Hct: -7.08 % (± 4.7 %, range: -4.70 - -9.90 G/L); Hb: -2.36 g/dL (± 1.6 g/dL, range: -1.50. - -3.40 g/dL). We did not observe significant differences in transfusion frequency between the two study cohorts (p = 0.735 for THA, p = 0.273 for HA). No influence of patient positioning on Hb-decrease, Hct-decrease, or RBC-decrease was noted in our two-way ANOVA models with consideration of implant type and fixation technique (F(3,618) = 1.838, p = 0.139; F(3,618) = 2.606, p = 0.051; F(3,618) = 1.407, p = 0.240). CONCLUSIONS: We did not observe  significant differences in perioperative blood values and transfusion rates in association with patient positioning in patients undergoing hip replacement surgery for femoral neck fractures. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Mid- and Long-Term Outcome After Arthroscopically Assisted Transosseous Triangular Fibrocartilage Complex Refixation-Good to Excellent Results in Spite of Some Loss of Stability of the Distal Radioulnar Joint.

PURPOSE: To evaluate mid- and long-term outcomes after arthroscopically-assisted transosseous reattachment of the triangular fibrocartilage complex (TFCC) and to analyze the association of distal radioulnar joint (DRUJ) stability with the clinical outcome. METHODS: Patients treated with an arthroscopically-assisted transosseous reattachment of the deep layer of the TFCC between 2000 and 2009 and a minimum follow-up of 12 months at mid-term and 4 years at long-term follow-up were retrospectively reviewed. Mayo Modified Wrist Score (MMWS); Disabilities of the Arm, Shoulder and Hand (DASH) score; pain visual analogue scale (VAS); grip strength and stability of the DRUJ were assessed at 2 follow-up clinical examinations. At the last follow-up, the Patient-Rated Wrist Evaluation score was additionally recorded. RESULTS: Thirty patients with a mean age of 29 (±13) years were included. Most of the patients were female (70%, n = 21). The mid-term evaluation took place at a median of 30 months (range, 12-83 months). The assessed scores showed statistically significant clinical improvement (MMWS, P < .001; DASH score P < .001; VAS P < .001). Stability assessment showed a stable DRUJ in 23 (76.7%) patients. At a median of 106 months (range 52-215 months), the long-term clinical assessment was performed. The evaluated scores demonstrated persisting significant improvement (MMWS P < .001; DASH score P < .001; VAS P < .001). Stability assessment showed a stable DRUJ in 19 patients (63.3%). DRUJ instability did not correlate with clinical outcome. No permanent surgery-related complications occurred. CONCLUSION: Arthroscopically-assisted transosseous reattachment of the deep fibers of radioulnar ligaments leads to excellent and good clinical results in mid- and long-term follow-up. In 95.5% of the analyzed patients, the measured improvement in the DASH score exceeded the in literature reported minimal clinically important difference of 13.5. Loss of DRUJ stability during follow-up was not associated with deterioration of clinical parameters and patient satisfaction. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Effects of hemodialysis on blood volume, macro- and microvascular function.

BACKGROUND: Vascular dysfunction is considered to spur the progression of cardiovascular disease in hemodialysis (HD) patients. Whether the HD procedure itself contributes to vascular dysfunction remains incompletely investigated. The present study sought to comprehensively assess the effects of HD on arterial and venous function along with concomitant changes in blood volume (BV). METHODS AND RESULTS: We determined BV with high-precision, automated carbon monoxide-rebreathing, arterial stiffness using applanation tonometry and intrinsic microvascular function via retinal vessel analysis prior to and after conventional 4-hour HD in fasting-controlled conditions in 10 patients. All HD patients were non-smokers and non-obese (body mass index = 22.8 ±â€¯2.8 m·kg-2). Hypertension (70%), coronary artery disease (40%) and diabetes mellitus (20%) were the most prevalent comorbidities. Prior to HD, all patients presented with hypervolemia (+2208 ±â€¯1213 ml). HD decreased body weight (-1.72 ±â€¯1.25 kg, P = 0.002) and plasma volume (-689 ±â€¯566 ml, P = 0.004), while hematocrit (Hct) was concomitantly increased (+4.8 ±â€¯4.5%, P = 0.009). HD did not affect large elastic artery stiffness, as determined by carotid-femoral pulse wave velocity (P = 0.448) and carotid distensibility (P = 0.562). In contrast, flicker light-induced retinal venular dilation was reduced by three-fourths after HD (-2.4 ±â€¯1.7%, P = 0.039), in parallel to increased retinal venular diameter (+11.2 ±â€¯4.9 µm, P = 0.002). In regression analyses, a negative association was observed between HD-induced changes in Hct and retinal venular dilation (r ≥ -0.89, P ≤ 0.045). CONCLUSION: Conventional HD resulting in substantial plasma volume removal do not alter large artery elastic properties, whereas intrinsic microvascular venular dilator function is markedly impaired, an effect directly associated with the increase in hemoconcentration.

Brachial plexus block with ultrasound guidance for upper-limb trauma surgery in children: a retrospective cohort study of 565 cases.

BACKGROUND: Upper-limb trauma is a common indication for surgery in children, and general anaesthesia remains the method of choice for these procedures, even though suitable techniques of brachial plexus block are available and fast provision of regional anaesthesia offers a number of distinct advantages. METHODS: A retrospective analysis was performed of the data of a large cohort of children undergoing ultrasound-guided brachial plexus blocks during a 4-yr period at a major trauma centre with a catchment area of 3.5 million. A total of 565 cases were sourced from two independently operating patient documentation systems. Patient data were stratified into age groups with block success as the primary outcome parameter. The influence of age on the incidence of block failure was assessed with logistic regression. RESULTS: The block failure rate was 5.1%, starting at 1.2% in the youngest (0-3 yr), then continuously increasing up to 12.5% in the oldest (15-18 yr) but also smallest group. Age emerged as an independent predictor of block failure with an odds ratio of 1.115 and a 95% confidence interval of 1.014-1.226 (P=0.025). No complications were observed. CONCLUSIONS: In a cohort of children receiving real-world care, with regional blocks performed by a range of anaesthetists with different skill levels, a success rate of 94.9% for upper-limb blocks in children under various levels of sedation was observed. Upper-limb blocks can be performed with high probability of success and an excellent margin of safety; this particularly applies to small children. CLINICAL TRIAL REGISTRATION: NCT03842423.

Oral activity of a nature-derived cyclic peptide for the treatment of multiple sclerosis.

Multiple sclerosis (MS) is the most common autoimmune disease affecting the central nervous system. It is characterized by auto-reactive T cells that induce demyelination and neuronal degradation. Treatment options are still limited and several MS medications need to be administered by parenteral application but are modestly effective. Oral active drugs such as fingolimod have been weighed down by safety concerns. Consequently, there is a demand for novel, especially orally active therapeutics. Nature offers an abundance of compounds for drug discovery. Recently, the circular plant peptide kalata B1 was shown to silence T-cell proliferation in vitro in an IL-2-dependent mechanism. Owing to this promising effect, we aimed to determine in vivo activity of the cyclotide [T20K]kalata B1 using the MS mouse model experimental autoimmune encephalomyelitis (EAE). Treatment of mice with the cyclotide resulted in a significant delay and diminished symptoms of EAE by oral administration. Cyclotide application substantially impeded disease progression and did not exhibit adverse effects. Inhibition of lymphocyte proliferation and the reduction of proinflammatory cytokines, in particular IL-2, distinguish the cyclotide from other marketed drugs. Considering their stable structural topology and oral activity, cyclotides are candidates as peptide therapeutics for pharmaceutical drug development for treatment of T-cell-mediated disorders.

Erythropoietin stimulates fibroblast growth factor 23 (FGF23) in mice and men.

Fibroblast growth factor 23 (FGF23) is a major endocrine regulator of phosphate and 1,25 (OH)2 vitamin D3 metabolism and is mainly produced by osteocytes. Its production is upregulated by a variety of factors including 1,25 (OH)2 vitamin D3, high dietary phosphate intake, and parathyroid hormone (PTH). Recently, iron deficiency and hypoxia have been suggested as additional regulators of FGF23 and a role of erythropoietin (EPO) was shown. However, the regulation of FGF23 by EPO and the impact on phosphate and 1,25(OH)2 vitamin D3 are not completely understood. Here, we demonstrate that acute administration of recombinant human EPO (rhEPO) to healthy humans increases the C-terminal fragment of FGF23 (C-terminal FGF23) but not intact FGF23 (iFGF23). In mice, rhEPO stimulates acutely (24 h) C-terminal FGF23 but iFGF23 only after 4 days without effects on PTH and plasma phosphate. 1,25 (OH)2 D3 levels and αklotho expression in the kidney decrease after 4 days. rhEPO induced FGF23 mRNA in bone marrow but not in bone, with increased staining of FGF23 in CD71+ erythroid precursors in bone marrow. Chronic elevation of EPO in transgenic mice increases iFGF23. Finally, acute injections of recombinant FGF23 reduced renal EPO mRNA expression. Our data demonstrate stimulation of FGF23 levels in mice which impacts mostly on 1,25 (OH)2 vitamin D3 levels and metabolism. In humans, EPO is mostly associated with the C-terminal fragment of FGF23; in mice, EPO has a time-dependent effect on both FGF23 forms. EPO and FGF23 may form a feedback loop controlling and linking erythropoiesis and mineral metabolism.

The influence of brain iron and myelin on magnetic susceptibility and effective transverse relaxation - A biochemical and histological validation study.

Quantitative susceptibility mapping (QSM) and effective transverse relaxation rate (R2*) mapping are both highly sensitive to variations in brain iron content. Clinical Magnetic Resonance Imaging (MRI) studies report changes of susceptibilities and relaxation rates in various neurological diseases which are often equated with changes in regional brain iron content. However, these mentioned metrics lack specificity for iron, since they are also influenced by the presence of myelin. In this study, we assessed the extent to which QSM and R2* reflect iron concentration as well as histological iron and myelin intensities. Six unfixed human post-mortem brains were imaged in situ with a 7 T MRI scanner. After formalin fixation, the brains were sliced axially and punched. 671 tissue punches were subjected to ferrozine iron quantification. Subsequently, brain slices were embedded in paraffin, and histological double-hemispheric axial brain slices were stained for Luxol fast blue (myelin) and diaminobenzidine (DAB)-enhanced Turnbull blue (iron). 3331 regions of interest (ROIs) were drawn on the histological stainings to assess myelin and iron intensities, which were compared with MRI data in corresponding ROIs. QSM more closely reflected quantitative ferrozine iron values (r = 0.755 vs. 0.738), whereas R2* correlated better with iron staining intensities (r = 0.619 vs. 0.445). Myelin intensities correlated negatively with QSM (r = -0.352), indicating a diamagnetic effect of myelin on susceptibility. Myelin intensities were higher in the thalamus than in the basal ganglia. A significant relationship was nonetheless observed between quantitative iron values and QSM, confirming the applicability of the latter in this brain region for iron quantification.

Increased serum concentrations of soluble ST2 are associated with pulmonary complications and mortality in polytraumatized patients.

BACKGROUND: We sought to evaluate the role of soluble ST2 (suppression of tumorigenicity) serum concentrations in polytraumatized patients and its potential role as biomarker for pulmonary complications. METHODS: We included severely injured patients (injury severity score≥16) admitted to our level I trauma center and analyzed serum samples obtained on the day of admission and on day 2. Furthermore, patients with isolated thoracic injury and healthy probands were included and served as control groups. Serum samples were analyzed for soluble ST2 concentrations with a commercially available ELISA kit. RESULTS: A total of 130 patients were included in the present study. Five patients with isolated thoracic injury and eight healthy probands were further included. Serum analyses revealed significantly elevated concentrations of soluble ST2 in polytraumatized patients compared to patients suffering from isolated thoracic trauma and healthy probands. In polytraumatized patients who developed pulmonary complications (acute respiratory distress syndrome and pneumonia) and in patients who died, significantly higher serum concentrations of soluble ST2 were found on day 2 (p<0.001). Serum concentrations of soluble ST2 on day 2 were of prognostic value to predict pulmonary complications in polytraumatized patients (area under the curve=0.720, 95% confidence interval=0.623-0.816). Concomitant thoracic trauma had no further impact on serum concentrations of soluble ST2. CONCLUSIONS: Serum concentrations of soluble ST2 are upregulated following polytrauma. Increased concentrations were associated with worse outcome.

Increased serum concentrations of soluble ST2 predict mortality after burn injury.

BACKGROUND: Large burn injuries induce a systemic response in affected patients. Soluble ST2 (sST2) acts as a decoy receptor for interleukin-33 (IL-33) and has immunosuppressive effects. sST2 has been described previously as a prognostic serum marker. Our aim was to evaluate serum concentrations of sST2 and IL-33 after thermal injury and elucidate whether sST2 is associated with mortality in these patients. METHODS: We included 32 burn patients (total body surface area [TBSA] >10%) admitted to our burn intensive care unit and compared them to eight healthy probands. Serum concentrations of sST2 and IL-33 were measured serially using an enzyme-linked immunosorbent assay (ELISA) technique. RESULTS: The mean TBSA was 32.5%±19.6%. Six patients (18.8%) died during the hospital stay. Serum analyses showed significantly increased concentrations of sST2 and reduced concentrations of IL-33 in burn patients compared to healthy controls. In our study cohort, higher serum concentrations of sST2 were a strong independent predictor of mortality. CONCLUSIONS: Burn injuries cause an increment of sST2 serum concentrations with a concomitant reduction of IL-33. Higher concentrations of sST2 are associated with increased in-hospital mortality in burn patients.

Femoral shortening does not impair functional outcome after internal fixation of femoral neck fractures in non-geriatric patients.

INTRODUCTION: Aim of this study was to investigate the incidence and extent of femoral shortening in non-geriatric patients after internal fixation of femoral neck fractures in relation to the clinical outcome at mid-term follow-up. MATERIALS AND METHODS: Reviewing our admission data, we identified non-geriatric patients (18-65 years) with femoral neck fractures treated with either dynamic hip screw or cancellous screws between 2007 and 2015. Patients were then contacted and invited to a follow-up clinical investigation including whole-leg standing X-rays. RESULTS: A total of 40 patients with a mean age at surgery of 52 ± 9 years returned for the follow-up examination. Overall, 31 patients (77.5%) had undergone a dynamic hip screw fixation, while 9 patients were treated with cancellous screws (22.5%). The median follow-up time was 65.5 months (5.5 years). We observed shortening of the ipsilateral femur neck in the majority of cases (92.5%). Still, functional outcome in the overall study population was excellent with a median Harris Hip Score of 96. CONCLUSIONS: Femoral neck shortening is common in non-geriatric patients after internal fixation of femoral neck fractures. Nonetheless, observed excellent functional outcome at mid-term follow-up supports joint-preserving strategies in non-geriatric femoral neck fractures.

Aquaporin 1 controls the functional phenotype of pulmonary smooth muscle cells in hypoxia-induced pulmonary hypertension.

Vascular remodelling in hypoxia-induced pulmonary hypertension (PH) is driven by excessive proliferation and migration of endothelial and smooth muscle cells. The expression of aquaporin 1 (AQP1), an integral membrane water channel protein involved in the control of these processes, is tightly regulated by oxygen levels. The role of AQP1 in the pathogenesis of PH, however, has not been directly addressed so far. This study was designed to characterize expression and function of AQP1 in pulmonary vascular cells from human arteries and in the mouse model of hypoxia-induced PH. Exposure of human pulmonary vascular cells to hypoxia significantly induced the expression of AQP1. Similarly, levels of AQP1 were found to be upregulated in lungs of mice with hypoxia-induced PH. The functional role of AQP1 was further tested in human pulmonary artery smooth muscle cells demonstrating that depletion of AQP1 reduced proliferation, the migratory potential, and, conversely, increased apoptosis of these cells. This effect was associated with higher expression of the tumour suppressor gene p53. Using the mouse model of hypoxia-induced PH, application of GapmeR inhibitors targeting AQP1 abated the hypoxia-induced upregulation of AQP1 and, of note, reversed PH by decreasing both right ventricular pressure and hypertrophy back to the levels of control mice. Our data suggest an important functional role of AQP1 in the pathobiology of hypoxia-induced PH. These results offer novel insights in our pathogenetic understanding of the disease and propose AQP1 as potential therapeutic in vivo target.

Erythropoiesis with endurance training: dynamics and mechanisms.

The purpose of the present study was to characterize the progression of red blood cell volume (RBCV) expansion and potential volumetric and endocrine regulators of erythropoiesis during endurance training (ET). Nine healthy, untrained volunteers (age = 27 ± 4 yr) underwent supervised ET consisting of 3-4 × 60 min cycle ergometry sessions per week for 8 wk. Plasma volume (PV), RBCV, and overnight fasting hematological markers were determined before and at weeks 2, 4, and 8 of ET. In addition, plasma erythropoietin (EPO), cortisol, copeptin, and proatrial natriuretic peptide concentrations were measured during a 3-h morning period at baseline and postexercise at weeks 1 and 8 PV increased from baseline (2,405 ± 335 ml) at weeks 2, 4, and 8 (+374 ± 194, +505 ± 156, and +341 ± 160 ml, respectively, P < 0.001). Increases in RBCV from baseline (1,737 ± 442 ml) were manifested at week 4 (+109 ± 114 ml, P = 0.030) and week 8 (+205 ± 109 ml, P = 0.001). Overnight fasting plasma EPO concentration increased from baseline (11.3 ± 4.8 mIU/ml) at week 2 (+2.5 ± 2.8 mIU·ml-1, P = 0.027) and returned to baseline concentration at weeks 4 and 8 Higher 3-h-postexercise EPO concentration was observed at week 1 (11.6 mIU/ml) compared with week 8 (8.4 ± 3.9 mIU/ml, P = 0.009) and baseline (9.0 ± 4.2 mIU/ml, P = 0.019). Linear relationships between EPO concentration and hematocrit (ß = -56.2, P < 0.001) and cortisol (ß = 0.037, P < 0.001) were detected throughout the ET intervention. In conclusion, ET leads to mild, transient increases in circulating EPO concentration, concurring with early PV expansion and lowered hematocrit, preceding gradual RBCV enhancement.

Combined effects of physical inactivity and acute hyperglycemia on arterial distensibility.

Arterial distensibility, an independent predictor of cardiovascular events, is transiently increased with acute hyperglycemia (AHG) in healthy individuals. Whether this response interacts with physical inactivity remains unknown. We examined the effects of short-term bed rest (BR) on the response of carotid artery distensibility (CD) to AHG, and the influence of underlying changes in insulin resistance and blood volume. CD was assessed with ultrasonography before as well as 30 and 120 minutes following ingestion of 75 g of glucose prior to and after 3 days of BR in 15 healthy male volunteers. Plasma insulin/glucose concentrations and blood volumes were concomitantly determined. On day 4 of BR, blood volume was re-established to pre-BR levels by albumin infusion and CD and insulin/glucose concentrations were determined as in the previous experimental days. Basal CD was not affected by BR. AHG increased CD before and after BR but reached a higher peak increment after BR (12% vs 60% at 30 min OGTT, p=0.028). BR also increased the plasma insulin concentration during AHG ( p=0.007). In regression analyses, plasma insulin and glucose concentrations were positively correlated to CD, particularly after BR ( r=0.31, p<0.05). Restoration of the BR-induced loss (5%) in blood volume did not affect the response of CD to AHG. In conclusion, short-term physical inactivity strongly accentuates the initial increase in CD in response to AHG in healthy individuals. This effect is associated with concomitant increases in circulating insulin concentration attributable to early insulin resistance.

Loss of Phosphatase and Tensin Homolog in APCs Impedes Th17-Mediated Autoimmune Encephalomyelitis.

The PI3K signaling cascade in APCs has been recognized as an essential pathway to initiate, maintain, and resolve immune responses. In this study, we demonstrate that a cell type-specific loss of the PI3K antagonist phosphatase and tensin homolog (PTEN) in myeloid cells renders APCs toward a regulatory phenotype. APCs deficient for PTEN exhibit reduced activation of p38 MAPK and reduced expression of T cell-polarizing cytokines. Furthermore, PTEN deficiency leads to upregulation of markers for alternative activation, such as Arginase 1, with concomitant downregulation of inducible NO synthase in APCs in vitro and in vivo. As a result, T cell polarization was dysfunctional in PTEN(-/-) APCs, in particular affecting the Th17 cell subset. Intriguingly, mice with cell type-specific deletions of PTEN-targeting APCs were protected from experimental autoimmune encephalomyelitis, which was accompanied by a pronounced reduction of IL-17- and IL-22-producing autoreactive T cells and reduced CNS influx of classically activated monocytes/macrophages. These observations support the notion that activation of the PI3K signaling cascade promotes regulatory APC properties and suppresses pathogenic T cell polarization, thereby reducing the clinical symptoms and pathology of experimental autoimmune encephalomyelitis.

The MAPK-Activated Kinase MK2 Attenuates Dendritic Cell-Mediated Th1 Differentiation and Autoimmune Encephalomyelitis.

Dendritic cell (DC)-mediated inflammation induced via TLRs is promoted by MAPK-activated protein kinase (MK)-2, a substrate of p38 MAPK. In this study we show an opposing role of MK2, by which it consolidates immune regulatory functions in DCs through modulation of p38, ERK1/2-MAPK, and STAT3 signaling. During primary TLR/p38 signaling, MK2 mediates the inhibition of p38 activation and positively cross-regulates ERK1/2 activity, leading to a reduction of IL-12 and IL-1α/ß secretion. Consequently, MK2 impairs secondary autocrine IL-1α signaling in DCs, which further decreases the IL-1α/p38 but increases the anti-inflammatory IL-10/STAT3 signaling route. Therefore, the blockade of MK2 activity enables human and murine DCs to strengthen proinflammatory effector mechanisms by promoting IL-1α-mediated Th1 effector functions in vitro. Furthermore, MK2-deficient DCs trigger Th1 differentiation and Ag-specific cytotoxicity in vivo. Finally, wild-type mice immunized with LPS in the presence of an MK2 inhibitor strongly accumulate Th1 cells in their lymph nodes. These observations correlate with a severe clinical course in DC-specific MK2 knockout mice compared with wild-type littermates upon induction of experimental autoimmune encephalitis. Our data suggest that MK2 exerts a profound anti-inflammatory effect that prevents DCs from prolonging excessive Th1 effector T cell functions and autoimmunity.