A role for TASK2 channels in the human immunological synapse

The immunological synapse is a transient junction that occurs when the plasma membrane of a T cell comes in close contact with an APC after recognizing a peptide from the antigen-MHC. The interaction starts when CRAC channels embedded in the T cell membrane open, flowing calcium ions into the cell. To counterbalance the ion influx and subsequent depolarization, K_v1.3 and KCa3.1 channels are recruited to the immunological synapse, increasing the extracellular K⁺ concentration. These processes are crucial as they initiate gene expression that drives T cell activation and proliferation. The T cell-specific function of the K_2P channel family member TASK2 channels and their role in autoimmune processes remains unclear. Using mass spectrometry analysis together with epifluorescence and super-resolution single-molecule localization microscopy, we identified TASK2 channels as novel players recruited to the immunological synapse upon stimulation. TASK2 localizes at the immunological synapse, upon stimulation with CD3 antibodies, likely interacting with these molecules. Our findings suggest that, together with K_v1.3 and KCa3.1 channels, TASK2 channels contribute to the proper functioning of the immunological synapse, and represent an interesting treatment target for T cell-mediated autoimmune disorders.     

Clopidogrel Resistance in Neurovascular Stenting: Correlations between Light Transmission Aggregometry,VerifyNow, and the Multiplate

BACKGROUND AND PURPOSE:Clopidogrel resistance is blamed for thromboembolic complications in neurovascular stent placement. Platelet-function assays are weakly standardized. The aim of this study was to correlate the results of 3 different platelet-inhibition measurements (from light transmission aggregometry, the VerifyNow P2Y12 test, and the Multiplate analyzer) and their relation to periprocedural thromboembolic complications in elective neurovascular stent placement.MATERIALS AND METHODS:Clopidogrel resistance was determined on the day of the intervention according to predefined platelet reactivity cutoff values. All 3 tests were performed in 103 consecutive neurovascular stent-placement procedures in 97 patients (extracranial, n = 77; intracranial, n = 26).RESULTS:The clopidogrel resistance rates were 47.6% (light transmission aggregometry), 50.5% (VerifyNow), and 35.9% (Multiplate). In 67% of the patients, clopidogrel resistance was present according to at least one method. The correlations of qualitative results that classified a patient as responsive or resistant to clopidogrel were 67.9% for light transmission aggregometry with VerifyNow, 77.7% for light transmission aggregometry with the Multiplate, and 66% for VerifyNow with the Multiplate. Periprocedural thromboembolic complications (n = 9) occurred more frequently in patients who were determined by all 3 methods to be clopidogrel resistant. The difference was most pronounced with light transmission aggregometry (complication rates, 14.4% [clopidogrel-resistant patients] vs 3.7% [clopidogrel-responsive patients]). Sensitivity and specificity rates of clopidogrel resistance in relation to embolic complications were, respectively, 78% and 55% for light transmission aggregometry, 67% and 51% for VerifyNow, and 44% and 67% for the Multiplate.CONCLUSIONS:Clopidogrel resistance is a frequent finding in patients who undergo neurovascular stent placement. The correlations among the different testing methods are only modest and differ considerably. Light transmission aggregometry results seem to correlate with thromboembolic complications more accurately than with VerifyNow and Multiplate point-of-care methods.

In neurovascular procedures, especially the placement of a stent into an extracranial or intracranial artery, clopidogrel resistance is associated with an increased risk of thromboembolic complications.^1–5 In elective neurovascular stent placement, preprocedural testing of platelet inhibition is increasingly performed to identify patients with clopidogrel resistance. However, test result standards for clopidogrel resistance have not been established, and strong clinical evidence that supports the idea that the results of such tests definitively alter clinical outcomes is still lacking. Light transmission aggregometry (LTA) is considered the criterion-standard test method, but standard values have not yet been established. LTA requires a preparation time of 2 hours, whereas point-of-care methods such as the VerifyNow P2Y12 assay (Accumetrics, San Diego, California) and impedance aggregometry using a Multiplate analyzer (Dynabyte, Munich, Germany) offer periprocedural test results within minutes in the operating suite.⁶A study comparing LTA with point-of-care measurements in percutaneous coronary intervention has shown only modest agreement among the different tests.⁷ In neurovascular procedures, clopidogrel resistance has been investigated with various methods. However, a comparison of different test methods to determine the correlation of their results with the occurrence of embolic complications has not yet been performed in the clinical context of neurovascular stent placement.The purpose of this study was to determine the correlation of platelet inhibition with clopidogrel according to 3 different testing methods and the association of clopidogrel resistance with thromboembolic complications in elective neurovascular stent placement.     

Clinical features and outcome of T-cell acute lymphoblastic leukemia in childhood with respect to alterations at the TAL1 locus: a Pediatric Oncology Group study

Alteration of the TAL1 locus is the most common nonrandom genetic defect in childhood T-cell acute lymphoblastic leukemia (T-ALL). To determine if rearrangements of the TAL1 proto-oncogene confer a distinct leukemic phenotype, we studied leukemic peripheral blood or bone marrow samples from 182 children with newly diagnosed T-ALL enrolled on Pediatric Oncology Group treatment protocols. Forty-eight (26%) of the samples had a local rearrangement of the TAL1 locus. Demographic and clinical features were compared for patient subgroups with and without TAL1 rearrangements. The only clinical correlates that were significantly associated with TAL1 gene rearrangements were higher white blood cell count (P = .017) and higher hemoglobin (P = .007) at diagnosis. Immunophenotypically, samples with altered TAL1 were more likely to be CD2+ (P = .001) and lack CD10 (cALLa) expression (P = .007) than those without the rearrangement. There was a trend toward improved event-free survival (EFS) in patients with TAL1 rearrangements (4-year EFS was 44% +/- 7% for patients without the rearrangements v 59% +/- 11% for those with rearrangements), but the difference was not significant (P = .34). The role of TAL1 in leukemogenesis has yet to be clearly defined, and the prognostic significance of TAL1 gene rearrangements in T-ALL deserves further study.     

IgMs produced by two acquired immune deficiency syndrome lymphoma cell lines: Ig binding specificity and VH-gene putative somatic mutation analysis [published erratum appears in Blood 1994 Aug 1;84(3):995]

Two B-cell lines, 2F7 and 10C9, were established by single cell cloning from biopsies obtained from two acquired immune deficiency syndrome patients with Burkitt's lymphoma. Representation of the original tumors was verified by demonstration of (1) identical biallelic rearrangement of Ig genes for 2F7 and (2) shared idiotype for 10C9. Both cell lines displayed cell-surface Ig and secreted Ig (IgM lambda for 2F7, IgM kappa for 10C9). IgMs from both cell lines immunoprecipitated actin; in addition, 2F7 IgM lambda immunoprecipitated recombinant human immunodeficiency virus type 1 (HIV-1) gp 160. 2F7 IgM lambda did not react with other autoantigens (double-stranded and single-stranded DNA, actin, bovine serum albumin, IgG), whereas 10C9 IgM kappa reacted with human IgG. The 2F7 IgM heavy-chain variable region (VH) showed a 95% nucleotide homology with a previously sequenced VHIII germline gene, hv3019b9, whereas the 10C9 IgM VH showed a 95% homology with a previously sequenced VHIV germline gene, VH4.21. Use of minimally modified VH genes and demonstration of reactivity with chronically present antigens (ie, actin, HIV-1 gp 160, or human IgG) suggests that B cells in HIV-1-infected individuals proliferating in response to chronic antigenic stimulation may be at increased risk for lymphomagenesis.     

Response to desmopressin is influenced by the genotype and phenotype in type 1 von Willebrand disease (VWD): results from the European Study MCMDM-1VWD

We have prospectively evaluated the biologic response to desmopressin in 77 patients with type 1 von Willebrand disease (VWD) enrolled within the Molecular and Clinical Markers for the Diagnosis and Management of type 1 VWD project. Complete response to desmopressin was defined as an increase of both ristocetin cofactor activity (VWF:RCo) and factor VIII coagulant activity (FVIII:C) to 50 IU/dL or higher and partial response as VWF:RCo or FVIII:C lower than 50 IU/dL after infusion, but at least 3-fold the basal level. Complete response was observed in 83% of patients; partial in 13%; and no response in 4%. Patients with some abnormality of VWF multimeric pattern had significantly lower basal FVIII:C and VWF, lower VWF:RCo/Ag ratio, and less complete responses to desmopressin than patients with a normal multimeric pattern (P=.002). Patients with mutations at codons 1130 and 1205 in the D'-D3 domain had the greatest relative increase, but shortest FVIII and VWF half-lives after infusion. Most partial and nonresponsive patients had mutations in the A1-A3 domains. Response to desmopressin in these VWD patients seemed to be associated with the location of the causative mutation. The presence of subtle multimeric abnormalities did not hamper potential clinically useful responses, as in typical type 1 VWD.     

ATG16L1 and NOD2 polymorphisms enhance phagocytosis in monocytes of Crohn’s disease patients

AIM:To investigate if the presence of relevant genetic polymorphisms has effect on the effectual clearance of bacteria by monocytes and granulocytes in patients with Crohn’s disease(CD).METHODS:In this study,we assessed the differential responses in phagocytosis by measuring the phagocytic activity and the percentage of active phagocytic monocytes and granulocytes in inflammatory bowel disease patients as well as healthy controls.As both autophagy related like 1(ATG16L1)and immunityrelated guanosine triphosphatase gene are autophagy genes associated with CD and more recently nucleo-tide-binding ligomerization domain-containing protein2(NOD2)has been identified as a potent inducer of autophagy we genotyped the patients for these variants and correlated this to the phagocytic reaction.The genotyping was done with restriction fragment length polymorphisms analysis and the phagocytosis was determined with the pHrodo?Escherichia coli Bioparticles Phagocytosis kit for flowcytometry.RESULTS:In this study,we demonstrate that analysis of the monocyte and granulocyte populations of patients with CD and ulcerative colitis showed a comparable phagocytic activity(ratio of mean fluorescence intensity)between the patient groups and the healthy controls.CD patients show a significantly higher phagocytic capacity(ratio mean percentage of phagocytic cells)compared to healthy controls(51.91%±2.85%vs 37.67%±7.06%,P=0.05).The extend of disease was not of influence.However,variants of ATG16L1(WT:2.03±0.19 vs homozygoot variant:4.38±0.37,P<0.009)as well as NOD2(C-ins)(heterozygous variant:42.08±2.94 vs homozygous variant:75.58±4.34(P=0.05)are associated with the phagocytic activity in patients with CD.CONCLUSION:Monocytes of CD patients show enhanced phagocytosis associated with the presence of ATG16L1 and NOD2 variants.This could be part of the pathophysiological mechanism resulting in the disease.     

An unusual case of vaccine-associated paralytic poliomyelitis

The present article reports a case involving an immunocompetent, previously well child who, despite two previous doses of inactivated poliovirus vaccine, developed severe flaccid paralysis consistent with polio after receiving oral polio vaccine.     

Evidence for a role of anti-ADAMTS13 autoantibodies despite normal ADAMTS13 activity in recurrent thrombotic thrombocytopenic purpura

Background

Severe ADAMTS13 deficiency is a critical component of the pathogenesis of idiopathic thrombotic thrombocytopenic purpura but is found only in about 60% of patients clinically diagnosed with this disease.

Design and Methods

Over a period of 8 years and six episodes of thrombotic thrombocytopenic purpura we studied the evolution of the anti-ADAMTS13 antibody response in a patient using different ADAMTS13 assays and epitope mapping.

Results

Anti-ADAMTS13 autoantibodies were found in all episodes but were inhibitory only in the last two episodes. In a flow-based assay, normal ADAMTS13 activity was found only during the first disease episode, while ADAMTS13 activity was normal using a static assay in episodes 1 and 3, and severely deficient in the last two episodes. Fluorescence evolution in a modified fluorescence resonance energy transfer assay using a von Willebrand factor A2 domain peptide substrate was linear in episodes 1, 5 and 6, but increased exponentially in episodes 3 and 4. Despite the variable functional characteristics of the anti-ADAMTS13 autoantibodies, their principal epitope was the ADAMTS13 spacer domain in all episodes.

Conclusions

The patient is unique as he displayed features of maturation or shaping of the anti-ADAMTS13 autoantibody response during the course of multiple episodes of thrombotic thrombocytopenic purpura. Anti-ADAMTS13 autoantibodies may be important in vivo despite normal ADAMTS13 activity in routine assays. Consequently, treatment decisions should not be based solely on activity assay results.     

The impact of periodontitis on oral health‐related quality of life: a review of the evidence from observational studies

Modern population based oral health management requires a complete understanding of the impact of disease in order to provide efficient and effective oral health care and guidance. Periodontitis is an important cause of tooth loss and has been shown to be associated with a number of systemic conditions. The impact of oral conditions and disorders on quality of life has been extensively studied. However, the impact of periodontitis on quality of life has received less attention. This review summarizes the literature on the impact of periodontitis on oral health‐related quality of life (OHRQoL). Relevant publications were identified after searching the MEDLINE and EMBASE electronic databases. Screening of titles and abstracts and data extraction was conducted. Only observational studies were included in this review. Most of the reviewed studies reported a negative impact of periodontitis on OHRQoL. However, the reporting standards varied across studies. Moreover, most of the studies were conducted in developed countries.