Factor IX variants improve gene therapy efficacy for hemophilia B

Intramuscular injection of adeno-associated viral (AAV) vector to skeletal muscle of humans with hemophilia B is safe, but higher doses are required to achieve therapeutic factor IX (F.IX) levels. The efficacy of this approach is hampered by the retention of F.IX in muscle extracellular spaces and by the limiting capacity of muscle to synthesize fully active F.IX at high expression rates. To overcome these limitations, we constructed AAV vectors encoding F.IX variants for muscle- or liver-directed expression in hemophilia B mice. Circulating F.IX levels following intramuscular injection of AAV-F.IX-K5A/V10K, a variant with low-affinity to extracellular matrix, were 2-5 fold higher compared with wild-type (WT) F.IX, while the protein-specific activities remained similar. Expression of F.IX-R338A generated a protein with 2- or 6-fold higher specific activity than F.IX-WT following vector delivery to skeletal muscle or liver, respectively. F.IX-WT and variant forms provide effective hemostasis in vivo upon challenge by tail-clipping assay. Importantly, intramuscular injection of AAV-F.IX variants did not trigger antibody formation to F.IX in mice tolerant to F.IX-WT. These studies demonstrate that F.IX variants provide a promising strategy to improve the efficacy for a variety of gene-based therapies for hemophilia B.     

High rates of depressive symptoms among patients with systemic sclerosis are not explained by differential reporting of somatic symptoms

OBJECTIVE: Between 36% and 65% of patients with systemic sclerosis (SSc) report symptoms of depression above cutoff thresholds on self-report questionnaires. The objective of this study was to assess whether these high rates result from differential reporting of somatic symptoms related to the high physical burden of SSc. METHODS: Symptom profiles reported on the Center for Epidemiologic Studies Depression Scale (CES-D) were compared between a multicenter sample of 403 patients with SSc and a sample of respondents to an Internet depression survey, matched on total CES-D score, age, race/ethnicity, and sex. An exact nonparametric generalized Mantel-Haenszel procedure was used to identify differential item functioning between groups. RESULTS: Patients with SSc reported significantly higher frequencies (moderate to large effect size; P < 0.01) on 4 CES-D somatic symptom items: bothered, appetite, effort, and sleep. Internet respondents had higher item scores on 2 items that assessed interpersonal difficulties (unfriendly, large effect size; P < 0.01; disliked, large effect size; P < 0.01) and on 2 items that assessed lack of positive effect (happy, moderate effect size; P = 0.01; enjoy, large effect size; P < 0.01). Adjustment of standard CES-D cutoff criteria for potential bias due to somatic symptom reporting resulted in a reduction of only 3.6% in the number of SSc patients with significant symptoms of depression. CONCLUSION: High rates of depressive symptoms in SSc are not due to bias related to the report of somatic symptoms. The pattern of differential item functioning between the SSc and Internet groups, however, suggests some qualitative differences in depressive symptom presentation.     

C-C chemokine receptor 2 and sarcoidosis: association with Lofgren's syndrome

Sarcoidosis is thought to result from the interaction between an unknown environmental antigenic trigger and the host's genetic susceptibility. We hypothesized that sarcoidosis, or one of the disease subsets, could be associated with single nucleotide polymorphisms of C-C chemokine receptor 2 (CCR2) gene. Eight single-nucleotide polymorphisms in CCR2 were studied in a total of 304 Dutch individuals (90 non-L?fgren sarcoidosis, 47 L?fgren's syndrome, 167 control subjects). From the investigated CCR2 polymorphisms, nine haplotypes were deduced (haplotypes 1-9). In patients with L?fgren's syndrome, a strongly significant increase in the frequency of CCR2-haplotype 2, which includes four unique alleles (A at nucleotide position -6752, A at 3,000, T at 3,547, and T at 4,385), was observed compared with control subjects (74% vs. 38% respectively, p < 0.0001), whereas no difference was found between non-L?fgren sarcoidosis and control subjects (both 38%). The association between CCR2-haplotype 2 carriage frequency and L?fgren's syndrome (odds ratio, 4.4; p < 0.0001) remained significant after adjustment for human leukocyte antigen haplotype DRB1*0301-DQB1*0201 (odds ratio, 11.5; p < 0.0001) and female sex (odds ratio, 3.2; p = 0.003), two known risk factors for L?fgren's syndrome. In conclusion, this report describes a strong association between CCR2-haplotype 2 and L?fgren's syndrome. Further studies are needed to understand the molecular mechanisms underlying this association.