Modulation of regulatory T-cell activity in combination with interleukin-12 increases hepatic tolerogenicity in woodchucks with chronic hepatitis B

Regulatory T cells (Treg) play a critical role in the modulation of immune responses to viral antigens in chronic viral hepatitis. Woodchucks (Marmota monax) infected with the woodchuck hepatitis virus (WHV) represent the best animal model for chronic hepatitis B virus (HBV) infection. Examination of intrahepatic and peripheral Treg in uninfected and WHV chronically infected woodchucks showed a significant increase of intrahepatic Treg numbers in chronically infected animals, whereas no differences were found in peripheral blood. In agreement with these data, higher expression levels of Forkhead box P3 (Foxp3), interleukin (IL)-10, transforming growth factor beta (TGF-β) were detected in the liver of chronic WHV carriers in comparison to uninfected animals. Furthermore, treatment of WHV-infected animals with an adenovirus encoding IL-12 failed to reduce viral load, a finding that was associated with lymphocyte unresponsiveness to IL-12 stimulation in vitro. We observed that TGF-β and Treg play a major role in the lack of lymphocyte response to IL-12 stimulation, as TGF-β inhibition and Treg depletion allowed recovery of T-cell responsiveness to this cytokine. Based on these results, woodchucks were treated with IL-12 in combination with a TGF-β inhibitory peptide or Treg depletion. However, no antiviral effect was achieved and, instead, an enhancement of the intrahepatic tolerogenic environment was observed. CONCLUSION: Our data show that TGF-β inhibition or Treg depletion had no added benefit over IL-12 therapy in chronic WHV infection. IL-12 immunostimulation induces a strong immunosuppressive reaction in the liver of chronic WHV carriers that counteracts the antiviral effect of the treatment.     

Genetic variability at the TREX1 locus is not associated with natural resistance to HIV-1 infection

Three prime repair exonuclease 1 (TREX1) degrades excess HIV-1 DNA, thereby preventing recognition by innate immunity receptors and type I interferon responses. Analyses performed in two HIV-exposed seronegative (HESN) cohorts did not show any differences in TREX1 sequence, single nucleotide polymorphisms frequency, or expression in HESN compared to controls, suggesting that, despite its central role in the HIV-1 infection process, genetic diversity at TREX1 is not a major determinant of susceptibility to infection in humans.     

Constitutively released adenosine diphosphate regulates proplatelet formation by human megakaryocytes

Background

The interaction of adenosine diphosphate with its P2Y₁ and P2Y₁₂ receptors on platelets is important for platelet function. However, nothing is known about adenosine diphosphate and its function in human megakaryocytes.

Design and Methods

We studied the role of adenosine diphosphate and P2Y receptors on proplatelet formation by human megakaryocytes in culture.

Results

Megakaryocytes expressed all the known eight subtypes of P2Y receptors, and constitutively released adenosine diphosphate. Proplatelet formation was inhibited by the adenosine diphosphate scavengers apyrase and CP/CPK by 60-70% and by the P2Y₁₂ inhibitors cangrelor and 2-MeSAMP by 50-60%, but was not inhibited by the P2Y₁ inhibitor MRS 2179. However, the active metabolites of the anti-P2Y₁₂ drugs, clopidogrel and prasugrel, did not inhibit proplatelet formation. Since cangrelor and 2-MeSAMP also interact with P2Y₁₃, we hypothesized that P2Y₁₃, rather than P2Y₁₂ is involved in adenosine diphosphate-regulated proplatelet formation. The specific P2Y₁₃ inhibitor MRS 2211 inhibited proplatelet formation in a concentration-dependent manner. Megakaryocytes from a patient with severe congenital P2Y₁₂ deficiency showed normal proplatelet formation, which was inhibited by apyrase, cangrelor or MRS 2211 by 50-60%. The platelet count of patients with congenital delta-storage pool deficiency, who lack secretable adenosine diphosphate, was significantly lower than that of patients with other platelet function disorders, confirming the important role of secretable adenosine diphosphate in platelet formation.

Conclusions

This is the first demonstration that adenosine diphosphate released by megakaryocytes regulates their function by interacting with P2Y₁₃. The clinical relevance of this not previously described physiological role of adenosine diphosphate and P2Y₁₃ requires further exploration.Key words: ADP, proplatelet formation, P2Y13 receptor     

Neural intersections of the phonological,visual magnocellular and motor/cerebellar systems in normal readers: Implications for imaging studies on dyslexia

We used fMRI to explore the extent of the anatomical overlap of three neural systems that the literature on developmental dyslexia associates with reading: the auditory phonological, the visual magnocellular, and the motor/cerebellar systems. Twenty‐eight normal subjects performed four tasks during fMRI scans: word and pseudoword reading, auditory rhyming for letter names, visual motion perception, and a motor sequence learning task. We found that the left occipitotemporal cortex (OTC), which previous studies reported to be dysfunctional in dyslexia, can be fractionated into different functional areas: an anterior and lateral area that was activated by both reading and auditory rhyming tasks; a posterior area that was commonly activated by both the reading and the motion perception task and a medial/intermediate area, including the so‐called Visual Word Form Area, which was specifically activated by the reading task. These results show that the left OTC is an area of segregated convergence of different functional systems. We compared our results with the hypoactivation pattern reported for reading in a previous cross‐cultural PET study on 36 dyslexic subjects from three countries. The region of decreased activation in dyslexia overlapped with regions that are specific for reading and those activated during both the auditory rhyming task and the single word and pseudoword reading task described in the present fMRI study. No overlap was found with the activation patterns for the visual motion perception task or for the motor sequence learning task. These observations challenge current theories of dyslexia. Hum Brain Mapp 34:2669–2687, 2013. © 2012 Wiley Periodicals, Inc.     

Modulating Human Procedural Learning by Cerebellar Transcranial Direct Current Stimulation

Neuroimaging studies suggest that the cerebellum contributes to human cognitive processing, particularly procedural learning. This type of learning is often described as implicit learning and involves automatic, associative, and unintentional learning processes. Our aim was to investigate whether cerebellar transcranial direct current stimulation (tDCS) influences procedural learning as measured by the serial reaction time task (SRTT), in which subjects make speeded key press responses to visual cues. A preliminary modeling study demonstrated that our electrode montage (active electrode over the cerebellum with an extra-cephalic reference) generated the maximum electric field amplitude in the cerebellum. We enrolled 21 healthy subjects (aged 20–49 years). Participants did the SRTT, a visual analogue scale and a visual attention task, before and 35 min after receiving 20-min anodal and sham cerebellar tDCS in a randomized order. To avoid carry-over effects, experimental sessions were held at least 1 week apart. For our primary outcome measure (difference in RTs for random and repeated blocks) anodal versus sham tDCS, RTs were significantly slower for sham tDCS than for anodal cerebellar tDCS (p?=?0.04), demonstrating that anodal tDCS influenced implicit learning processes. When we assessed RTs for procedural learning across the one to eight blocks, we found that RTs changed significantly after anodal stimulation (interaction “time”?×?“blocks 1/8”: anodal, p?=?0.006), but after sham tDCS, they remained unchanged (p?=?0.094). No significant changes were found in the other variables assessed. Our finding that anodal cerebellar tDCS improves an implicit learning type essential to the development of several motor skills or cognitive activity suggests that the cerebellum has a critical role in procedural learning. tDCS could be a new tool for improving procedural learning in daily life in healthy subjects and for correcting abnormal learning in neuropsychiatric disorders.     

PP2A Ligand ITH12246 Protects against Memory Impairment and Focal Cerebral Ischemia in Mice

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Oral mucosa produces cytokines and factors influencing osteoclast activity and endothelial cell proliferation, in patients with osteonecrosis of jaw after treatment with zoledronic acid

Objectives

The intravenous injection of bisphosphonates, currently used as treatment for osteoporosis, bone Paget’s disease, multiple myeloma, or bone metastases, can cause jaw bone necrosis especially in consequence of trauma. The present research aimed to clarify the mechanisms underlying bone necrosis, exploring involvement of the oral mucosa “in vivo.”

Patients and methods

Specimens of oral mucosa were removed from bisphosphonate-treated patients with or without jaw bone necrosis. In mucosa specimens, expression was evaluated of: cytokines involved in the inflammatory process, factors involved in osteoclast activity, i.e., receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin, a factor involved in cell proliferation, namely hydroxymethylglutaryl coenzyme A reductase, and a factor involved in angiogenesis, namely vascular endothelial growth factor (VEGF).

Results

Interleukin (IL)-6 and the RANK/osteoprotegerin ratio were significantly elevated in mucosa from patients with versus without jaw necrosis, whereas hydroxymethylglutaryl coenzyme A reductase and VEGF were significantly decreased.

Conclusions

Our results suggest that mucosa, stimulated by bisphosphonate released from the bone, can contribute to the development of jaw necrosis, reducing VEGF, and producing IL-6 in consequence of hydroxymethylglutaryl coenzyme A reductase reduction. In turn, IL-6 stimulates osteoclast activity, as shown by the increased RANKL/osteoprotegerin ratio.

Clinical relevance

The results of this study suggest the importance of evaluating during bisphosphonate treatment the production of IL-6, RANKL, osteoprotegerin, and VEGF, in order to monitor the jaw osteonecrosis onset. To avoid repeated mucosa excisions, the determination of these factors could be carried out in crevicular fluid.     

Coronary artery anomalies

Coronary artery anomalies (CAAs) are a rare entity but their true incidence in the general population has yet to be determined. Most CAAs are asymptomatic, but they are nevertheless the second leading cause of sudden death in apparently healthy young athletes. The new imaging methods available to cardiologists, including CT angiography and MRI, now enable noninvasive diagnosis and characterization of these anomalies. The authors review the literature and present a retrospective study of 360 consecutive patients who underwent cardiac CT angiography. Demographic, clinical and angiographic characteristics were studied. The incidence of CAAs in this population was 2.69%. In order to better characterize this disorder, including diagnostic strategy, screening, treatment and prognosis, the authors suggest the establishment of a national registry of cardiac CT angiography. Such a registry would fill the existing gap in information on exams performed in the country, enriching current knowledge about this disease and noninvasive cardiac imaging in Portugal.     

Exaggerated blood pressure response during exercise treadmill testing: functional and hemodynamic features, and risk factors

The factors which contribute to an exaggerated blood pressure response (EBPR) during the exercise treadmill test (ETT) are not wholly understood. The association between the insertion/deletion polymorphisms of the angiotensin-converting enzyme (ACE) and M235T of the angiotensinogen with EBPR during ETT still remains unstudied. To identify and compare the risk factors for hypertension between normotensive subjects with EBPR and those who exhibit a normal curve of blood pressure (BP) during ETT. In a series of EBPR cases from a historical cohort of normotensive individuals, a univariate analysis was performed to estimate the association of the studied factors with BP behavior during ETT. Additionally, logistic multivariate regression was conducted to analyze the joint effects of the variables. P-values above 0.05 were considered statistically significant. From a total of 10,027 analyzed examinations, only 219 met the criteria employed to define EBPR, which resulted in a prevalence of 12.6%. For the systolic component of the BP, hyperreactive subjects displayed a mean age and body mass index (BMI) significantly higher than the others (P=0.002 and <0.001, respectively). No association was observed between the polymorphisms cited above and EBPR. An analysis of the joint effect of variables has indicated that only age (P< 0.001) and BMI (P=0.001) were specifically associated with systolic BP during exercise. Age and BMI were the only factors that independently influenced EBPR during ETT.