High prevalence of familial defective apolipoprotein B-100 in Switzerland

Familial defective apolipoprotein B-100 (FDB) is caused by a single G-to-A substitution at nucleotide 10,708 leading to an arginine to glutamine change at amino acid 3,500 of the apolipoprotein B-100 and thus, a reduced binding of the apolipoprotein B to the low density lipoprotein (LDL) receptor. In the present study, the prevalence of FDB in Switzerland was estimated, on the one hand, from a sample of 728 healthy volunteers whose origin was spread out over the entire German, French, and Romansh speaking parts of the country, and, on the other hand, from 142 unrelated Swiss families with primary hypercholesterolemia comprising 520 individuals. Using polymerase chain reaction (PCR)-based methods, three individuals were identified with the point mutation in the sample of volunteers, equivalent to a prevalence of approximately 1/240 (90% confidence interval: 1.51 x 10(-3)-1.03 x 10(-2)). The frequency of FDB in the sample of hypercholesterolemic subjects was 7/142, yielding a prevalence of approximately 1/190 extrapolated to the general population (90% confidence interval: 2.63 x 10(-3)-9.17 x 10(-2)). The combined prevalence based on both samples was 1/209. Thus, the investigated point mutation was highly prevalent in Switzerland and appeared to be more frequent than in other populations studied hitherto. Furthermore, the presence of the mutation was not necessarily associated with an elevation of serum cholesterol levels, particularly in young individuals. While in the non-affected volunteers cholesterol levels increased between the age of 19 and 23 years by 0.22 mmol/l or by 5.6% (P = 0.001), this phenomenon was even more pronounced in individuals with FDB. The three volunteers with the point mutation demonstrated an increase in total cholesterol concentrations by 1.30 mmol/l or by 25% within 2 years, suggesting that, in the early twenties, cholesterol concentrations increase markedly from normal to elevated levels. Considering the estimated high prevalence the relative ease of PCR-based tests, screening for FDB may become a standard procedure in patients with suggested familial forms of hypercholesterolemia

PID Group INGV: a bridge towards Open Data

Costituzione del PID Group INGV e presentazione degli obiettiviUnpublishedCNR Piazzale Aldo Moro Roma7TM. Sviluppo e Trasferimento Tecnologicoope

PID Group INGV: a bridge towards Open Data

Costituzione del PID Group INGV e presentazione degli obiettiv

Polymorphic haplotypes and recombination rates at the LDL receptor gene locus in subjects with and without familial hypercholesterolemia who are from different populations.

RFLPs at the low-density lipoprotein (LDL) receptor locus for TaqI, StuI, HincII, AvaII, ApaLI (5' and 3'), PvuII, and NcoI were studied in Swiss and German families with familial hypercholesterolemia (FH). A total of 1,104 LDL receptor alleles were analyzed using Southern blotting and new PCR-based techniques for detection of the TaqI, StuI, HincII, AvaII, NcoI RFLPs. Two hundred fifty-six independent haplotypes from 368 individuals of 61 unrelated Swiss families, as well as 114 independent haplotypes from 184 subjects of 25 unrelated German families, were constructed. In 76 families, clinical diagnosis of FH was confirmed by cosegregation analysis. Of the 43 unique haplotypes consisting of seven RFLPs detected in the Swiss and Germans, only 9 were common in both population samples. Analysis of linkage disequilibrium revealed nonrandom associations between several of the investigated RFLPs. ApaLI (5'), NcoI, PvuII, TaqI, and AvaII or HincII were particularly informative (cumulative informativeness .85). Relative frequencies, heterozygosity indexes, and PICs of the RFLPs from the Swiss and Germans were compared with values calculated from reported haplotype data for Italians, Icelanders, North American Caucasians, South African Caucasians, and Japanese. Pairwise comparisons of population samples by common RFLPs demonstrated unexpected differences even between geographically adjacent populations (e.g., the Swiss and Germans). Furthermore, genetic distances from the Germans to the other Caucasians were larger than to the Japanese. An unexpected lack of correlation between linkage disequilibria and physical distances was detected for the German and Japanese data, possibly because of nonuniform recombination with excessively high rates between exon 13 and intron 15. Hence, the present study revealed a striking variety of polymorphic haplotypes and heterogeneity of RFLP frequencies and recombination rates among the seven population samples

Duration of antigen receptor signaling determines T-cell tolerance or activation

The early events that determine the decision between lymphocyte tolerance and activation are not well-understood. Using a model of systemic self-antigen recognition by CD4+ T cells, we show, using single-cell biochemical analyses, that tolerance is characterized by transient signaling events downstream of T-cell receptor engagement in the mammalian target of rapamycin (mTOR) and NF-κB pathways. Parallel studies done by live cell imaging show that the key difference between tolerance and activation is the duration of the T cell–antigen presenting cell (APC) interaction, as revealed by stable T-cell immobilization on antigen encounter. Brief T cell–APC interactions result in tolerance, and prolonged interactions are associated with activation and the development of effector cells. These studies show that the duration of T cell–APC interactions and magnitude of associated TCR-mediated signaling are key determinants of lymphocyte tolerance vs. activation

Abrogating Cbl-b in effector CD8+ T cells improves the efficacy of adoptive therapy of leukemia in mice

The clinical use of adoptive immunotherapy with tumor-reactive T cells to treat established cancers is limited in part by the poor in vivo survival and function of the transferred T cells. Although administration of exogenous cytokines such as IL-2 can promote T cell survival, such strategies have many nonspecific activities and are often associated with toxicity. We show here that abrogating expression of Casitas B-lineage lymphoma b (Cbl-b), a negative regulator of lymphocyte activation, in tumor-reactive CD8+ T cells expanded ex vivo increased the efficacy of adoptive immunotherapy of disseminated leukemia in mice. Mechanistically, Cbl-b abrogation bypassed the requirement for exogenous IL-2 administration for tumor eradication in vivo. In addition, CD8+ T cells lacking Cbl-b demonstrated a lower threshold for activation, better survival following target recognition and stimulation, and enhanced proliferative responses as a result of both IL-2–dependent and –independent pathways. Importantly, siRNA knockdown of Cbl-b in human CD8+CD28– effector T cell clones similarly restored IL-2 production and proliferation following target recognition independent of exogenous IL-2, enhanced IFN-γ production, and increased target avidity. Thus, abrogating Cbl-b expression in effector T cells may improve the efficacy of adoptive therapy of some human malignancies

Role of antigen persistence and dose for CD4+ T-cell exhaustion and recovery

It is currently not understood how some chronic infections exhaust antigen-specific T cells over time and which pathogen components contribute to exhaustion. Here, we dissected the behavior of primed CD4+ T cells exposed to persistent antigen using an inducible transgenic mouse system that allowed us to control antigen presentation as the only experimental variable, independent of the persistent inflammation and disease progression that complicate infectious models. Moreover, this system restricted antigen presentation to dendritic cells (DCs) and avoided confounding B, CD8+ T, or innate cell responses. When antigen presentation was extended beyond the expansion phase, primed CD4+ T cells survived, but exhibited reduced memory functionality in terms of their proliferative capacity and cytokine expression potential. The effect was antigen dose and time dependent, not associated with increased PD-1 expression or reduced calcium influx, but impaired Jun phosphorylation in response to TCR engagement. Upon antigen removal, the cells regained the ability to proliferate, but remained unable to produce high levels of IL-2 and TNF-α. These data show that persistent antigen by itself rapidly induces a dysfunctional state in CD4+ T cells that is only partially reversible upon antigen removal. These findings have implications for vaccine optimization and for the possible reinvigoration of CD4+ T cells during chronic infection