Receptor activator of nuclear factor-κB ligand and osteoprotegerin: maintaining the balance to prevent bone loss

Bone remodeling requires a precise balance between resorption and formation. It is a complex process that involves numerous factors: hormones, growth factors, vitamins, and cytokines, and notably osteoprotegerin (OPG) and receptor activator for nuclear factor-κB (RANK) ligand. The signaling pathway OPG/RANK/RANKL is key to regulation for maintaining the balance between the activity of osteoblasts and osteoclasts in order to prevent bone loss and ensure a normal bone turnover. In this review, the RANK/RANKL/OPG pathway is described. The multiple interactions of various factors (hormones, cytokines, growth factors, and vitamins) with the OPG/RANK/RANKL pathway are also commented on. Finally, the effects of denosumab, a human monoclonal antibody that binds to RANKL and thereby inhibits the activation of osteoclasts, and of strontium ranelate are also described. Indeed, these two new drugs afford appreciable assistance in daily care practice, helping to prevent bone loss in patients with osteoporosis

Both cladribine and alemtuzumab may effect MS via B-cell depletion.

OBJECTIVE: To understand the efficacy of cladribine (CLAD) treatment in MS through analysis of lymphocyte subsets collected, but not reported, in the pivotal phase III trials of cladribine and alemtuzumab induction therapies. METHODS: The regulatory submissions of the CLAD Tablets Treating Multiple Sclerosis Orally (CLARITY) (NCT00213135) cladribine and Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis, study one (CARE-MS I) (NCT00530348) alemtuzumab trials were obtained from the European Medicine Agency through Freedom of Information requests. Data were extracted and statistically analyzed. RESULTS: Either dose of cladribine (3.5 mg/kg; 5.25 mg/kg) tested in CLARITY reduced the annualized relapse rate to 0.16-0.18 over 96 weeks, and both doses were similarly effective in reducing the risk of MRI lesions and disability. Surprisingly, however, T-cell depletion was rather modest. Cladribine 3.5 mg/kg depleted CD4+ cells by 40%-45% and CD8+ cells by 15%-30%, whereas alemtuzumab suppressed CD4+ cells by 70%-95% and CD8+ cells by 47%-55%. However, either dose of cladribine induced 70%-90% CD19+ B-cell depletion, similar to alemtuzumab (90%). CD19+ cells slowly repopulated to 15%-25% of baseline before cladribine redosing. However, alemtuzumab induced hyperrepopulation of CD19+ B cells 6-12 months after infusion, which probably forms the substrate for B-cell autoimmunities associated with alemtuzumab. CONCLUSIONS: Cladribine induced only modest depletion of T cells, which may not be consistent with a marked influence on MS, based on previous CD4+ T-cell depletion studies. The therapeutic drug-response relationship with cladribine is more consistent with lasting B-cell depletion and, coupled with the success seen with monoclonal CD20+ depletion, suggests that B-cell suppression could be the major direct mechanism of action

Guidelines for translational research in heart failure

Heart failure (HF) remains a major cause of death and hospitalization worldwide. Despite medical advances, the prognosis of HF remains poor and new therapeutic approaches are urgently needed. The development of new therapies for HF is hindered by inappropriate or incomplete preclinical studies. In these guidelines, we present a number of recommendations to enhance similarity between HF animal models and the human condition in order to reduce the chances of failure in subsequent clinical trials. We propose different approaches to address safety as well as efficacy of new therapeutic products. We also propose that good practice rules are followed from the outset so that the chances of eventual approval by regulatory agencies increase. We hope that these guidelines will help improve the translation of results from animal models to humans and thereby contribute to more successful clinical trials and development of new therapies for HF.European Union [CardioNeT-ITN-289600, CardioNext-ITN-608027, FP7-IMI-JU-SAFET-115003]; Spanish Ministry of Economy [SAF2012-31451]; Regional Government of Madrid [2010-BMD-2321]; Spanish Ministry of Economy; Pro-CNIC Foundation; NIH [HL-120732, HL100401]; AHA [14SFRN20740000]; CPRIT [RP110486P3]; Leducq Foundation [11CVD04]; MINECO-SAF [2013-42962R]; Instituto Carlos III [TERCEL-RD-12/00190026, RIC12/00420024]S

The functional maturation of M cells is dramatically reduced in the Peyer's patches of aged mice

The transcytosis of antigens across the follicle-associated epithelium (FAE) of Peyer's patches by microfold cells (M cells) is important for the induction of efficient immune responses to mucosal antigens. The mucosal immune response is compromised by ageing, but effects on M cells were unknown. We show that M-cell density in the FAE of aged mice was dramatically reduced. As a consequence, aged Peyer's patches were significantly deficient in their ability to transcytose particulate lumenal antigen across the FAE. Ageing specifically impaired the expression of Spi-B and the downstream functional maturation of M cells. Ageing also dramatically impaired C-C motif chemokine ligand 20 expression by the FAE. As a consequence, fewer B cells were attracted towards the FAE, potentially reducing their ability to promote M-cell maturation. Our study demonstrates that ageing dramatically impedes the functional maturation of M cells, revealing an important ageing-related defect in the mucosal immune system's ability to sample lumenal antigens

Bone Biomarkers Help Grading Severity of Coronary Calcifications in Non Dialysis Chronic Kidney Disease Patients

BACKGROUND: Osteoprotegerin (OPG) and fibroblast growth factor-23 (FGF23) are recognized as strong risk factors of vascular calcifications in non dialysis chronic kidney disease (ND-CKD) patients. The aim of this study was to investigate the relationships between FGF23, OPG, and coronary artery calcifications (CAC) in this population and to attempt identification of the most powerful biomarker of CAC: FGF23? OPG? METHODOLOGY/PRINCIPAL FINDINGS: 195 ND-CKD patients (112 males/83 females, 70.8 [27.4-94.6] years) were enrolled in this cross-sectional study. All underwent chest multidetector computed tomography for CAC scoring. Vascular risk markers including FGF23 and OPG were measured. Logistic regression analyses were used to study the potential relationships between CAC and these markers. The fully adjusted-univariate analysis clearly showed high OPG (≥10.71 pmol/L) as the only variable significantly associated with moderate CAC ([100-400[) (OR = 2.73 [1.03;7.26]; p = 0.04). Such association failed to persist for CAC scoring higher than 400. Indeed, severe CAC was only associated with high phosphate fractional excretion (FEPO(4)) (≥38.71%) (OR = 5.47 [1.76;17.0]; p = 0.003) and high FGF23 (≥173.30 RU/mL) (OR = 5.40 [1.91;15.3]; p = 0.002). In addition, the risk to present severe CAC when FGF23 level was high was not significantly different when OPG was normal or high. Conversely, the risk to present moderate CAC when OPG level was high was not significantly different when FGF23 was normal or high. CONCLUSIONS: Our results strongly suggest that OPG is associated to moderate CAC while FGF23 rather represents a biomarker of severe CAC in ND-CKD patients

Comparison of Bone and Renal Effects In HIV-infected Adults Switching to Abacavir or Tenofovir Based Therapy in a Randomized Trial

Our objective was to compare the bone and renal effects among HIV-infected patients randomized to abacavir or tenofovir-based combination anti-retroviral therapy.In an open-label randomized trial, HIV-infected patients were randomized to switch from zidovudine/lamivudine (AZT/3TC) to abacavir/lamivudine (ABC/3TC) or tenofovir/emtricitabine (TDF/FTC). We measured bone mass density (BMD) and bone turnover biomarkers (osteocalcin, osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), alkaline phosphatase, type I collagen cross-linked C-telopeptide (CTx), and osteoprotegerin). We assessed renal function by estimated creatinine clearance, plasma cystatin C, and urinary levels of creatinine, albumin, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL). The changes from baseline in BMD and renal and bone biomarkers were compared across study arms.Of 40 included patients, 35 completed 48 weeks of randomized therapy and follow up. BMD was measured in 33, 26, and 27 patients at baseline, week 24, and week 48, respectively. In TDF/FTC-treated patients we observed significant reductions from baseline in hip and lumbar spine BMD at week 24 (-1.8% and -2.5%) and week 48 (-2.1% and -2.1%), whereas BMD was stable in patients in the ABC/3TC arm. The changes from baseline in BMD were significantly different between study arms. All bone turnover biomarkers except osteoprotegerin increased in the TDF/FTC arm compared with the ABC/3TC arm, but early changes did not predict subsequent loss of BMD. Renal function parameters were similar between study arms although a small increase in NGAL was detected among TDF-treated patients.Switching to TDF/FTC-based therapy led to decreases in BMD and increases in bone turnover markers compared with ABC/3TC-based treatment. No major difference in renal function was observed.Clinicaltrials.gov NCT00647244

Chronic Citalopram Administration Causes a Sustained Suppression of Serotonin Synthesis in the Mouse Forebrain

BACKGROUND:Serotonin (5-HT) is a neurotransmitter with important roles in the regulation of neurobehavioral processes, particularly those regulating affect in humans. Drugs that potentiate serotonergic neurotransmission by selectively inhibiting the reuptake of serotonin (SSRIs) are widely used for the treatment of psychiatric disorders. Although the regulation of serotonin synthesis may be an factor in SSRI efficacy, the effect of chronic SSRI administration on 5-HT synthesis is not well understood. Here, we describe effects of chronic administration of the SSRI citalopram (CIT) on 5-HT synthesis and content in the mouse forebrain. METHODOLOGY/PRINCIPAL FINDINGS:Citalopram was administered continuously to adult male C57BL/6J mice via osmotic minipump for 2 days, 14 days or 28 days. Plasma citalopram levels were found to be within the clinical range. 5-HT synthesis was assessed using the decarboxylase inhibition method. Citalopram administration caused a suppression of 5-HT synthesis at all time points. CIT treatment also caused a reduction in forebrain 5-HIAA content. Following chronic CIT treatment, forebrain 5-HT stores were more sensitive to the depleting effects of acute decarboxylase inhibition. CONCLUSIONS/SIGNIFICANCE:Taken together, these results demonstrate that chronic citalopram administration causes a sustained suppression of serotonin synthesis in the mouse forebrain. Furthermore, our results indicate that chronic 5-HT reuptake inhibition renders 5-HT brain stores more sensitive to alterations in serotonin synthesis. These results suggest that the regulation of 5-HT synthesis warrants consideration in efforts to develop novel antidepressant strategies

Microfold (M) cells: important immunosurveillance posts in the intestinal epithelium

The transcytosis of antigens across the gut epithelium by microfold cells (M cells) is important for the induction of efficient immune responses to some mucosal antigens in Peyer’s patches. Recently, substantial progress has been made in our understanding of the factors that influence the development and function of M cells. This review highlights these important advances, with particular emphasis on: the host genes which control the functional maturation of M cells; how this knowledge has led to the rapid advance in our understanding of M-cell biology in the steady-state and during aging; molecules expressed on M cells which appear to be used as “immunosurveillance” receptors to sample pathogenic microorganisms in the gut; how certain pathogens appear to exploit M cells to infect the host; and finally how this knowledge has been used to specifically target antigens to M cells to attempt to improve the efficacy of mucosal vaccines

Right drug, right patient, right time: aspiration or future promise for biologics in rheumatoid arthritis?

Individualising biologic disease-modifying anti-rheumatic drugs (bDMARDs) to maximise outcomes and deliver safe and cost-effective care is a key goal in the management of rheumatoid arthritis (RA). Investigation to identify predictive tools of bDMARD response is a highly active and prolific area of research. In addition to clinical phenotyping, cellular and molecular characterisation of synovial tissue and blood in patients with RA, using different technologies, can facilitate predictive testing. This narrative review will summarise the literature for the available bDMARD classes and focus on where progress has been made. We will also look ahead and consider the increasing use of ‘omics’ technologies, the potential they hold as well as the challenges, and what is needed in the future to fully realise our ambition of personalised bDMARD treatment