Antibody and memory B cell responses to the dengue virus NS1 antigen in individuals with varying severity of past infection

To further understand the role of NS1-specific antibodies (Abs) in disease pathogenesis, we compared neutralizing antibody levels (Nabs), NS1-Ab levels, IgG antibody subclass profiles and NS1-specific memory B-cell responses (Bmems) in individuals, with varying severity of past dengue. Nabs (Neut50 titres) were assessed using the Foci Reduction Neutralization Test (FRNT) and in-house ELISAs were used to assess NS1-Abs and NS1-Ab subclasses for all four DENV serotypes in individuals with past DF (n = 22), those with past DHF (n = 14) and seronegative (SN) individuals (n = 7). B-cell ELISpot assays were used to assess NS1-specific Bmem responses. 15/22 (68.18%) individuals with past DF and 9/14 (64.29%) individuals with past DHF had heterotypic infections. Neut50 titres were found to be significantly higher for DENV1 than DENV2 (p = 0.0006) and DENV4 (p = 0.0127), in those with past DHF, whereas there was no significant difference seen in titres for different DENV serotypes in those with past DF. Overall NS1-Ab to all serotypes and NS1-specific IgG1 responses for DENV1, 2 and 4 serotypes were significantly higher in those with past DHF than individuals with past DF. Those with past DHF also had higher IgG1 than IgG3 for DENV1 and DENV3, whereas no differences were seen in those with past DF. Over 50% of those with past DF or DHF had NS1-specific Bmem responses to >2 DENV serotypes. There was no difference in the frequency of Bmem responses to any of the DENV serotypes between individuals with past DF and DHF. Although the frequency of Bmem responses to DENV1 correlated with DENV1-specific NS1-Abs levels (Spearman r = 0.35, p = 0.02), there was no correlation with other DENV serotypes. We found that those with past DF had broadly cross-reactive Nabs, while those with past DHF had higher NS1-Ab responses possibly with a different functionality profile than those with past DF. Therefore, it would be important to further evaluate the functionality of NS1-specific antibody and Bmem responses to find out the type of antibody repertoire that is associated with protection against severe disease.     

High Levels of Zinc‐Protoporphyrin Identify Iron Metabolic Abnormalities in Pulmonary Arterial Hypertension

Iron homeostasis influences the development of pulmonary arterial hypertension (PAH) associated with hypoxia or hematologic disorders. To investigate whether severity of idiopathic PAH (IPAH) is impacted by alterations in iron metabolism, we assessed iron metabolic markers, including levels of zinc‐protoporphyrin (Zn‐pp), transferrin receptor, and red blood cell numbers and morphology in IPAH, associated PAH and sleep apnea‐induced pulmonary hypertension patients in comparison to healthy controls and asthmatics. Despite similarly normal measures of iron metabolism, Zn‐pp levels in IPAH and sleep apnea patients were elevated approximately twofold, indicating deficient iron incorporation to form heme and levels were closely related to measures of disease severity. Consistent with high Zn‐pp, PAH patients had increased red cell distribution width (RDW). In an expanded cohort including patients with IPAH and familial disease, the RDW was validated and related to clinical parameters of severity; including pulmonary artery pressures and 6‐minute walk distances. These results reveal an increased prevalence of subclinical functional iron deficiency in primary forms of PAH that is quantitatively related to disease severity. This suggests that altered iron homeostasis influences disease progression and demonstrates the importance of closely monitoring iron status in PAH patients. Clin Trans Sci 2011; Volume 4: 253–258     

Two novel factor V null mutations associated with activated protein C resistance phenotype/genotype discrepancy

Activated protein C (APC) resistance phenotype/genotype discrepancy is a very rare event. The objective of this study was to characterize the molecular mechanisms in two cases of APC phenotype/genotype discrepancy. An approach using direct sequencing of each exon and splicing junctions of the factor V gene showed that two novel factor V null mutations combined with heterozygous factor V Leiden mutation were responsible for this discrepancy. Our results suggest the necessity to use both phenotypic and genotypic analyses in some cases to determine an accurate diagnosis.     

Intraplaque hemorrhage: Its significance in cerebrovascular disease

Recently, carotid plaque factors, specifically intraplaque hemorrhage, have been studied with respect to the production of cerebrovascular symptoms. Ninety-five carotid endarterectomies were performed and the plaques that were removed were examined for intraplaque hemorrhage. Patients were separated into three groups: those with specific neurologic symptoms, those with nonlateralizing symptoms, and those who were asymptomatic. In the group of patients who presented with specific neurologic symptoms, correlation was made between the age of the intraplaque hemorrhage and the timing of symptoms.The vast majority of patients with specific neurologic symptoms exhibited carotid plaque hemorrhage, but patients with nonlateralizing symptoms and those who were asymptomatic also demonstrated an unexpectedly high percentage of intraplaque hemorrhage. Moreover, our results show a poor relationship between the timing of symptoms and the age of the intraplaque hemorrhage. These data do not refute the concept that intraplaque hemorrhage may play a role in the production of cerebrovascular symptoms, but they do refute the notion that the mere presence of hemorrhage causes specific neurologic symptoms and they also refute the previous report that demonstrates a good correlation between the timing of symptoms and the age of the intraplaque hemorrhage.     

Esophageal complications from combined chemoradiotherapy (cyclophosphamide + Adriamycin + cisplatin + XRT) in the treatment of non-small cell lung cancer

Esophageal complications from combined chemoradiotherapy (CCRT) were analyzed in 55 patients with limited non-small cell lung cancer. CCRT consisted of chemotherapy (cyclophosphamide, doxorubicin (Adriamycin), and cisplatin: CAP) and chest irradiation (5000 rad in 25 fractions/5 weeks). Forty-five patients received two courses of CAP, followed by five weekly courses of low dose CAP and irradiation followed by maintenance courses of CAP (Group 1). Ten patients received concomitant CCRT from the onset of treatment (Group 2). Esophagitis occurred in 80% of all patients. Severe esophagitis occurred in 27% of patients of Group 1 and 40% of patients of Group 2. Esophageal stricture or fistula developed in 1 of 45 (2%) patients in Group 1, and 3 of 10 (30%) patients in Group 2 (p less than 0.025). Weekly low-dose chemotherapy administered concomitantly with chest irradiation (R) at the onset of treatment significantly increases esophageal complications. A review of the literature suggests that CCRT may be used safely with split courses of R. The duration between onset of chemotherapy either before or after R should be greater than one week.     

Transcriptional repressor BCL-6 immortalizes germinal center-like B cells in the absence of p53 function

Chromosomal rearrangements in non-Hodgkin's B-cell lymphoma implicate BCL-6 as an oncogene, yet direct evidence for BCL-6 acting as an oncogene in B cells has been lacking. Here, we show that BCL-6 can immortalize primary B cells, but only in the absence of p53 tumor suppressor function. The expression of BCL-6 led to greatly increased B-cell proliferation, particularly in response to CD40 stimulation. Furthermore, BCL-6-infected p53-deficient B cells gave rise to immortalized cell lines that could be maintained by CD40 stimulation. We found that in primary mouse B cells, BCL-6 repressed expression of the Blimp-1, p27kip1, and cyclin D2 target genes. BCL-6 did not markedly repress the PDCD2 and BCL-XL target genes. The BCL-6 immortalized cell lines had a phenotype consistent with germinal center B cells, they expressed the germinal center-specific M17 gene, and a significant fraction of the cells stained positive with PNA. Our data indicate that BCL-6 may act to maintain B cells in a germinal center-like state, and repression of Blimp-1 by BCL-6 may be particularly crucial for stabilization of the germinal center phenotype. Our data also suggest that disruption of the p53 pathway may be crucial for the development of BCL-6-expressing B-cell lymphomas.