Using Optical Coherence Tomography and Optokinetic Response As Structural and Functional Visual System Readouts in Mice and Rats

Optical coherence tomography (OCT) is a fast, non-invasive, interferometric technique allowing high-resolution retinal imaging. It is an ideal tool for the investigation of processes of neurodegeneration, neuroprotection and neuro-repair involving the visual system, as these often correlate well with retinal changes. As a functional readout, visually evoked compensatory eye and head movements are commonly used in experimental models involving the visual function. Combining both techniques allows a quantitative in vivo investigation of structure and function, which can be used to investigate the pathological conditions or to evaluate the potential of novel therapeutics. A great benefit of the presented techniques is the possibility to perform longitudinal analyses allowing the investigation of dynamic processes, reducing variability and cuts down the number of animals needed for the experiments. The protocol described aims to provide a manual for acquisition and analysis of high quality retinal scans of mice and rats using a low cost customized holder with an option to deliver inhalational anesthesia. Additionally, the proposed guide is intended as an instructional manual for researchers using optokinetic response (OKR) analysis in rodents, which can be adapted to their specific needs and interests.

Mid-term follow-up after surgical treatment of fragility fractures of the pelvis

INTRODUCTION

Early operative treatment of fragility fractures of the pelvis (FFP) has been suggested to reduce pain and allow for earlier mobilization. The aim of this study was to determine mortality and functional outcome after operative treatment.

PATIENTS AND METHODS

Patients aged ≥60 years (n = 60; mean age 79 years, 53 female) who had operative treatment of a FFP and a follow-up of at least 2 years were identified and mortality was assessed using a national social insurance database. Those who had survived were contacted by phone and a modified Majeed Score was obtained.

RESULTS

At final follow up (62 months, range, 29-117), 32 patients (53.3%) had deceased. One-year-mortality rate was 28.3% and 2-year mortality was 36.7%. Mortality was not linked to fracture type (p > .05). Complications during hospitalization occurred in 26/60 patients (43.3%). Patients with a bilateral FFP had a longer hospitalization (18 vs. 11 days; p = .021). The mean modified Majeed score of surviving patients was 65 points (85.5% of achievable maximum).

CONCLUSION

Mortality and in-hospital complications remain high among patients with FFP even when treated operatively. A longer hospitalization can be expected in patients with posterior bilateral fractures.

Nur77 serves as a molecular brake of the metabolic switch during T cell activation to restrict autoimmunity

T cells critically depend on reprogramming of metabolic signatures to meet the bioenergetic demands during activation and clonal expansion. Here we identify the transcription factor Nur77 as a cell-intrinsic modulator of T cell activation. Nur77-deficient T cells are highly proliferative, and lack of Nur77 is associated with enhanced T cell activation and increased susceptibility for T cell-mediated inflammatory diseases, such as CNS autoimmunity, allergic contact dermatitis and collagen-induced arthritis. Importantly, Nur77 serves as key regulator of energy metabolism in T cells, restricting mitochondrial respiration and glycolysis and controlling switching between different energy pathways. Transcriptional network analysis revealed that Nur77 modulates the expression of metabolic genes, most likely in close interaction with other transcription factors, especially estrogen-related receptor α. In summary, we identify Nur77 as a transcriptional regulator of T cell metabolism, which elevates the threshold for T cell activation and confers protection in different T cell-mediated inflammatory diseases.

Cement augmentation of the Proximal Femoral Nail Antirotation (PFNA) - A multicentre randomized controlled trial

INTRODUCTION

New implant designs like the Proximal Femoral Nail Antirotation (PFNA) were developed to reduce failure rates in unstable pertrochanteric fractures in the elderly. Standardized implant augmentation with up to 6 mL of polymethylmethacrylate (PMMA) cement has been introduced to enhance implant anchorage by increasing the implant-bone interface in osteoporotic bone conditions. Biomechanically, loads to failure were significantly higher with augmentation. The primary objective of this study was to compare the mobility of patients with closed unstable trochanteric fractures treated by PFNA either with or without cement augmentation.

PATIENTS AND METHODS

A prospective multicentre, randomized, patient-blinded trial was conducted with ambulatory patients aged 75 or older who sustained a closed, unstable trochanteric fracture. Surgical fixation had to be performed within 72 h after admission. Outcomes were evaluated at baseline, during surgery, 3 to 14 days after surgery, 3 months, 6 months, and 12 months after surgery. To evaluate the primary objective, patients' walking speed was assessed by the Timed Up and Go (TUG) test. Secondary objectives included the analysis of implant migration assessed on radiographs, quality of life measured by the Barthel Index, mobility measured by the Parker Mobility Score, and complications.

RESULTS

Of 253 randomized patients, 223 patients were eligible: 105 patients were allocated to the PFNA Augmentation group and 118 to PFNA group. At 3 to 14 days after surgery, there was no statistical significant difference in mean walking speed between the treatment groups. For the secondary objectives, also no statistical significant differences were found. However, no patient in the PFNA Augmentation group had a reoperation due to mechanical failure or symptomatic implant migration compared to 6 patients in the PFNA group.

CONCLUSIONS

Augmentation of the PFNA blade did not improve patients' walking ability compared to the use of a non-augmented PFNA but might have the potential to prevent reoperations by strengthening the osteosynthesis construct.

Elevated Thrombomodulin Plasma Levels as a Result of Endothelial Involvement in Plasmodium falciparum Malaria

We used thrombomodulin (TM) to assess the participation of the vascular endothelium in human Plasmodium falciparum (P. F.) malaria. Before therapy TM plasma levels were elevated in P. F. malaria and fell to normal values during therapy. Parasitemia, TNFα, elastase and TAT levels correlated directly with TM. Elevated TM levels can not be explained by increased synthesis, since incubating HUVEC with pretherapy serum of patients with P. F. malaria, but not reconvalescence serum, suppressed TM transcription. This was partially prevented by adding a TNFα neutralizing antibody to patient serum before incubation with HUVEC. However, TNFα does not release TM from cultured HUVEC in vitro. Coincubation of HUVEC with pretherapy serum together with neutrophils resulted in endothelial cell destruction, which could be partly prevented by a TNFα neutralizing antibody. Hence the increase of TM during P. F. malaria might reflect the concerted action of cytokines and neutrophils on HUVEC.

Blood Coagulation and Thrombosis in Patients with Ovarian Malignancy

Ovarian cancer cells appear to be capable of both thrombin formation and induction of fibrin degradation which may be essential prerequisites for the development of deep vein thrombosis (DVT) as well as the spread of malignancy. To study further this coagulation – cancer interaction in 60 patients with untreated ovarian cancer of FIGO stage I-IV the incidence of DVT was recorded pre-operatively, postoperatively on day 1, 3, 5, 7, 10, before each of six cycles of Cisplati- num/Epirubicin/Cyclophosphamide chemotherapy, during follow-up and in the post-operative period of second look surgery. In addition, blood coagulation tests results were determined prospectively. Two patients were excluded from these calculations due to previous DVT 5 to 6 weeks before the diagnosis of ovarian cancer but all patients were eligible for surgery and randomized to receive either daily low molecular weight heparin (LMWH) (n = 28) or unfractionated heparin (UFH) (n = 32) for perioperative thrombosis prophylaxis until the 7th postoperative day. According to the FIGO stage, patients were equally distributed in the 2 heparin treatment groups. The predictive value of pre-operative coagulation test results, clinical parameters, and type of heparin used were tested in univariate and multivariate analysis for development of post-operative DVT and overall patients survival. Impedance plethysmography for DVT screening was used. The presence of DVT was then confirmed by phlebography. Only D-dimer and fibrinogen levels were correlated significantly with the FIGO stage while antithrombin, protein C, and plasminogen activator inhibitor activity were not. The incidence of DVT was 6.7% (4/60) up to the 7th and 8.3% (5/60) between the 8th and 29th post-operative day. DVT occurred in 10.6 % (5/47) during chemotherapy. Pre-operative coagulation test results, the type of heparin used, and clinical parameters were not significant risk factors for post-operative DVT development in univariate analysis. The D-dimer and fibrinogen levels were significant risk factors for reduced overall survival in univariate analysis but only the FIGO stage was an independent predictor (in multivariate analysis). After a median follow up of 26.5 months (min. 8 months, max. 41 months), 21.4% of LMWH treated and 37.5% of UFH-treated patients died of cancer (p = 0.26). Pre-operative test results were neither predictive for DVT nor the outcome of cancer but patients showed an improved though not statistically significant overall survival after LMWH treatment.

Antiparasitic Treatment of Patients with P. falciparum Malaria Reduces the Ability of Patient Serum to Induce Tissue Factor by Decreasing NF-κB Activation

Serum from patients with P. falciparum malaria at day 1 (pretherapy) induces tissue factor (TF) in cultured endothelial cells. TF induction depends on de novo transcription as shown in Nuclear Run On assays. Electrophoretic mobility shift assays demonstrated binding of AP-1 and NF- κB/Rel proteins to their recognition sites in the TF promotor. After therapy (day 28), stimulation of TF antigen by patient serum is reduced by 70%. When serum obtained before and after therapy was compared, a decrease of NF-κB activation was evident. Activation of NF-κB-like proteins was in part dependent on TNFα in patient serum, since a TNFα neutralizing antibody reduced induction of TF transcription and translation and induction of NF-κB-like proteins. Induction of TF activity was suppressed by pDTC, an inhibitor of NF-κB activation. When different promotor constructs of the TF gene were tested, induction was dependent upon the presence of the intact NF-κB-like binding site in the TF promotor. A mutant with deleted NF-κB, but intact AP-1 sites was not inducible. Mutation of the AP-1 sites did not prevent induction, but reduced inducibility by pretherapy serum. Therefore, NF-κB/Rel proteins are responsible for induction of TF transcription by pretherapy serum, but AP-1 is needed for highest inducibility. The effect of antiparasitic therapy on the induction of TF by serum from patients with complicated P. falciparum malaria is dependent on a therapy-mediated loss of activation of NF-κB-like proteins in post-treatment patient serum.

Tetracycline alters gene expression in Salmonella strains that harbor the Tn10 transposon

In this report, we show that bacterial plasmids that harbor the Tn10 transposon (i.e., the IncHI1 plasmid R27) modify expression of different Salmonella regulons responding to the presence of tetracycline (Tc) in the medium. By using as a model the Tc-dependent upregulation of the ibpAB operon (which belongs to the heat shock regulon), we have identified Tn10-tetA (coding for a Tc efflux pump) and adjacent tetC sequences as required for ibpAB upregulation. Characterization of transcripts in the tetAC region showed that tetA transcription can continue into tetC sequences, generating a long 3'UTR sequence, which can protect transcripts from RNA processing, thus increasing the expression of TetA protein. In the presence of Tc, the DnaK and IbpA chaperones are overexpressed and translocated to the periplasm and to the membrane fraction respectively. DnaK targeting unfolded proteins is known to induce heat shock by avoiding RpoH proteolysis. We correlate expression levels of Tn10-encoded TetA protein with heat shock induction in Salmonella, likely because TetA activity compromises protein secretion.

Cementless Stem for Femoral Neck Fractures in a Patient’s 10th Decade of Life: High Rate of Periprosthetic Fractures

Background:

Subsidence of cementless femoral stems in hemiarthroplasty (HA) and increased fracture rates are ongoing concerns of orthopedic surgeons when treating fractures in very old patients. Additionally, bone cement implantation syndrome may result in perioperative cardiac or pulmonary complications, especially in older patients, leading to morbidity and mortality. This study was performed to analyze possible subsidence and intraoperative fractures in a cohort of very old patients treated with cementless stems.

Methods:

We retrospectively analyzed a consecutive cohort of patients aged ≥90 years with femoral neck fractures treated by uncemented HA and an anterior minimally invasive approach. Immediate full-weight bearing was allowed postoperatively. Pelvic radiographs were examined for subsidence immediately postoperatively and 6 weeks later.

Results:

We treated 109 patients (74% women; mean age, 93 years; range, 90-102 years) by HA from January 2010 to March 2016. The 30-day mortality rate was 16%, and the morbidity rate was 47%. There were 11 (12%) intraoperative fractures: 8 (Vancouver B₂) had to be addressed immediately during the primary operation, while 3 (1 Vancouver B₁ and 2 Vancouver A_G) were treated conservatively. One periprosthetic femoral fracture (Vancouver B₁) was documented during follow-up. In 17 patients, subsidence of >2.0 mm (median, 3.9 mm; range, 2.5-9.0 mm) was documented.

Conclusion:

Early subsidence was low in this very old cohort treated with an uncemented stem and not showing a periprosthetic fracture. The risk of intraoperative periprosthetic fractures was high. The use of uncemented implants in osteoporotic bone continues to be an intervention with high risk and should only be performed by experienced surgeons.

Level of Evidence:

Level III, Therapeutic study.

Early alpha-lipoic acid therapy protects from degeneration of the inner retinal layers and vision loss in an experimental autoimmune encephalomyelitis-optic neuritis model

Background

In multiple sclerosis (MS), neurodegeneration is the main reason for chronic disability. Alpha-lipoic acid (LA) is a naturally occurring antioxidant which has recently been demonstrated to reduce the rate of brain atrophy in progressive MS. However, it remains uncertain if it is also beneficial in the early, more inflammatory-driven phases. As clinical studies are costly and time consuming, optic neuritis (ON) is often used for investigating neuroprotective or regenerative therapeutics. We aimed to investigate the prospect for success of a clinical ON trial using an experimental autoimmune encephalomyelitis-optic neuritis (EAE-ON) model with visual system readouts adaptable to a clinical ON trial.

Methods

Using an in vitro cell culture model for endogenous oxidative stress, we compared the neuroprotective capacity of racemic LA with the R/S-enantiomers and its reduced form. In vivo, we analyzed retinal neurodegeneration using optical coherence tomography (OCT) and the visual function by optokinetic response (OKR) in MOG_35–55-induced EAE-ON in C57BL/6J mice. Ganglion cell counts, inflammation, and demyelination were assessed by immunohistological staining of retinae and optic nerves.

Results

All forms of LA provided equal neuroprotective capacities in vitro. In EAE-ON, prophylactic LA therapy attenuated the clinical EAE score and prevented the thinning of the inner retinal layer while therapeutic treatment was not protective on visual outcomes.

Conclusions

A prophylactic LA treatment is necessary to protect from visual loss and retinal thinning in EAE-ON, suggesting that a clinical ON trial starting therapy after the onset of symptoms may not be successful.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1111-y) contains supplementary material, which is available to authorized users.

Nimodipine confers clinical improvement in two models of experimental autoimmune encephalomyelitis

Multiple sclerosis is characterised by inflammatory neurodegeneration, with axonal injury and neuronal cell death occurring in parallel to demyelination. Regarding the molecular mechanisms responsible for demyelination and axonopathy, energy failure, aberrant expression of ion channels and excitotoxicity have been suggested to lead to Ca2+ overload and subsequent activation of calcium-dependent damage pathways. Thus, the inhibition of Ca2+ influx by pharmacological modulation of Ca2+ channels may represent a novel neuroprotective strategy in the treatment of secondary axonopathy. We therefore investigated the effects of the L-type voltage-gated calcium channel blocker nimodipine in two different models of mouse experimental autoimmune encephalomyelitis (EAE), an established experimental paradigm for multiple sclerosis. We show that preventive application of nimodipine (10 mg/kg per day) starting on the day of induction had ameliorating effects on EAE in SJL/J mice immunised with encephalitic myelin peptide PLP139-151 , specifically in late-stage disease. Furthermore, supporting these data, administration of nimodipine to MOG35-55 -immunised C57BL/6 mice starting at the peak of pre-established disease, also led to a significant decrease in disease score, indicating a protective effect on secondary CNS damage. Histological analysis confirmed that nimodipine attenuated demyelination, axonal loss and pathological axonal β-amyloid precursor protein accumulation in the cerebellum and spinal cord in the chronic phase of disease. Of note, we observed no effects of nimodipine on the peripheral immune response in EAE mice with regard to distribution, antigen-specific proliferation or activation patterns of lymphocytes. Taken together, our data suggest a CNS-specific effect of L-type voltage-gated calcium channel blockade to inflammation-induced neurodegeneration.

Perioperative Fractures in Cementless Total Hip Arthroplasty Using the Direct Anterior Minimally Invasive Approach: Reduced Risk With Short Stems

BACKGROUND

The direct minimally invasive anterior approach (DMIAA) and the use of uncemented stems demonstrated an increase in intraoperative fractures in recent literature. Whether the different design of the stems additionally influences the incidence of perioperative local complications, was the goal of this study.

METHODS

From January 2008 until June 2010, all patients undergoing primary cementless total hip arthroplasty, using a DMIAA, were consecutively included. The choice of the implant was defined by the day of operation. Age, gender, body mass index, type of prosthesis, and the practical experience of the performing surgeon were retrospectively analyzed. Of main interest were intraoperative fractures, postoperative hematoma, and wound healing.

RESULTS

Six hundred forty consecutive patients (64 years [18-94], 339 female, 53%, body mass index 26) have been included. A Quadra-H stem (Medacta) was used in 457 patients (71%). In 183 (29%) patients, a short stem designed for the DMIAA (130 Fitmore, Zimmer and 53 AMIStem, Medacta) was used. We counted 34 (5.3%) intraoperative fractures (16 at the greater trochanter, 18 proximal shaft fractures), 20 (4%) hematomas, and 8 (2%) wound healing problems. The standard length stem showed more local complications (11.8% vs 4.4%) (P = .014, odds ratio 1.63, confidence interval 1.1-2.4) and significantly more (6.8% vs 1.6%) intraoperative fractures (P = .027, odds ratio 1.98, confidence interval 1.1-3.6).

CONCLUSION

The standard length stem showed more perioperative complications, especially periprosthetic fractures. It seems that these implants not only put more stress to proximal osseous structures, but there might also be more traction and irritation to the soft tissue while preparing, resulting in more hematomas and wound healing problems.

Systematically assessed symptoms as outcome predictors in emergency patients

INTRODUCTION

It is known that symptoms are predictive of mortality in "nonsurgical" emergency patients. It is unknown whether a prospective, systematic, and "unscreened" assessment of all symptoms is of any prognostic value. Therefore, we aimed to examine the association between symptoms and outcomes in an all-comer population.

METHODS

Data were acquired during 6weeks at the ED of the University Hospital Basel, a tertiary hospital. Consecutive patients presenting to the ED were included. Symptoms at presentation were systematically assessed using a comprehensive questionnaire.

RESULTS

A consecutive sample of 3960 emergency patients with a median age of 51years (51.7% male) was studied. The median number of symptoms was two. In the group of patients with the most prevalent symptoms, the median number of symptoms ranged between two and five. Overall, hospitalisation rate was 31.2%, referral to intensive care was 5.5%, in-hospital-mortality was 1.4%, and one-year mortality was 5.8%. In-hospital mortality ranged from 0% to 4.3%, and one-year mortality from 0% to 14.4% depending on the presenting symptoms. Dyspnoea and weakness were significant predictors of one-year mortality (14.4% and 9.2%, respectively).

DISCUSSION

Most emergency patients indicated two or more symptoms. Systematically assessed symptoms at presentation can be used for prediction of outcomes. While dyspnoea is a known predictor, weakness has not been identified as predictor of mortality before. This knowledge could be used to improve risk stratification- thereby reducing the risk of adverse outcomes.

Reverse shoulder arthroplasty for complex fractures of the proximal humerus in elderly patients: impact on the level of independency, early function, and pain medication

BACKGROUND

This study investigated early functional outcome, quality of life, and the level of independency in elderly patients after primary reverse shoulder arthroplasty (RSA) for complex fractures of the proximal humerus.

METHODS

This was a prospective case series that included 33 patients, aged ≥70 years, with a high level of independency who received RSA for complex fractures of the humerus (Orthopaedic Trauma Association B2/C) from January 2012 to April 2014.

RESULTS

Level of independency, quality of life (Short Form 36 Health Survey score), early functional outcome (Constant-Murley score, Disabilities of the Arm, Shoulder and Hand Outcome Measure), and pain medication (World Health Organization grading) were obtained at the 6-month follow-up and 1 year after surgery. The Constant-Murley score was 64 ± 14 after 6 months and 71 ± 12 at 1 year (P < .001), reaching 87% compared with the contralateral shoulder. The Disabilities of the Arm, Shoulder and Hand score reached 29 ± 20 at 6 months and 30 ± 21 at 1 year. The Short Form 36 score was comparable to normative data. After 6 months, 84% of our study group were back at their previous level of independency. Within 1 year, this rate increased to 91%. At the 1-year follow-up, analgesia intake was back at the level before the injury in 97% of the patients.

CONCLUSIONS

Primary RSA provides good early functional results, reliable pain control, and excellent restoration of an independent life style in elderly patients. Thus, RSA may be considered for active patients with a high demand on shoulder function.

Abstract OT3-07-01: A randomized trial evaluating bioimpedance spectroscopy vs. tape measurement in the prevention of lymphedema following breast cancer treatment

Background: Breast cancer related lymphedema (BCRL) represents a common treatment associated complication following surgery, radiation and/or chemotherapy. Increasing data has demonstrated the ability of new diagnostic modalities to detect BCRL in the subclinical phase of the process allowing for early intervention.

Trial Design: This 2-group stratified randomized clinical trial evaluates the effectiveness of bioimpedance spectroscopy (BIS) for early detection and prevention of BCRL compared to tape measurement (TM). Baseline assessments are made pre-operatively. Two-months post-op, patients are censored out if they have developed any of the exclusion conditions, did not have a mastectomy, axillary dissection, &gt;6 sentinel nodes removed, radiation therapy, or taxane. Remaining patients are randomized within site to either BIS or TM; monitored at 3 to 6-month intervals up to 36-months post-op for a change over baseline specified to trigger a compression sleeve & gauntlet intervention. Cohort trigger thresholds are change of ≥10 L-Dex units or 5 to &lt;10% volume. If the intervention is triggered, measurements by the other method are taken before initiating the 4-week intervention. Post intervention, patients are monitored only with TM. Volume change of ≥10% results in study removal and physician referral. At the 2 study endpoints (36 month visit or volume change of ≥10%) measurements are taken with each method.

Eligibility Criteria: Inclusion criteria: ≥ 18 with histologically confirmed stage I-III breast cancer (BC) or DCIS with planned surgery. Exclusion criteria include history of BC therapy or lymphedema.

Specific Aims: The primary hypothesis is that subclinical detection of BCRL with BIS and early intervention will reduce the rate of lymphedema progression (as measured by referral to complex decongestive physiotherapy) compared to TM. Secondary outcomes include BCRL risk factors, quality of life, and time to treatment.

Statistical Methods: Sample size and powering were based on the hypothesis that BIS would reduce progression rate by 20%. A rate of 50% progression in the TM group was used as the standard. 1100 patients will be enrolled to result in randomized groups of 100 (Total N=200) Statistics include relative risks with respective bootstrapped 95% C.I. and Cochran-Mantel-Haenszel tests.

Present Accrual and Target Accrual: Overall, the study target or expected enrollment as of the end of March 31, 2016 was 690 participants, 534 were actually enrolled (actual accrual 77% of target). Accrual at the study sites ranged from 15 to 104% of target.

Contact Information: Sheila Ridner: 615-322-0831, Sheila.ridner@vanderbilt.edu

Support: ImpediMed Limited, ImpediMed, Inc. and medi USA.

Citation Format: Ridner S, Shah C, Dietrich M, Vicini F. A randomized trial evaluating bioimpedance spectroscopy vs. tape measurement in the prevention of lymphedema following breast cancer treatment [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-07-01.

Absence of system xc- on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

BACKGROUND

Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x_c^- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration.

METHODS

Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x_c^-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT^-/-) mice and irradiated mice reconstituted in xCT^-/- bone marrow (BM), to their proper wild type (xCT^+/+) controls.

RESULTS

xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT^+/+ mice, xCT^-/- mice were equally susceptible to EAE, whereas mice transplanted with xCT^-/- BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected.

CONCLUSIONS

Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x_c^- on immune cells invading the CNS participates to EAE. Since a total loss of system x_c^- had no net beneficial effects, these results have important implications for targeting system x_c^- for treatment of MS.