No abstract

Neutron-proton pairing correlations are studied within the context of two solvable models, one based on the algebra SO(5) and the other on the algebra SO(8). Boson-mapping techniques are applied to these models and shown to provide a convenient methodological tool both for solving such problems and for gaining useful insight into general features of pairing. We first focus on the SO(5) model, which involves generalized T = 1 pairing. Neither boson meanfield methods nor fermion-pair approximations are able to describe in detail neutron-proton pairing in this model. The analysis suggests, however, that the boson Hamiltonian obtained from a mapping of the fermion Hamiltonian contains a pairing force between bosons, pointing to the importance of bosonboson (or equivalently four-fermion) correlations with isospin T = 0 and spin S = 0. These correlations are investigated by carrying out a second boson mapping. Closed forms for the fermion wave functions are given in terms of the fermion-pair operators. Similar techniques are applied -albeit in less detail -to the SO(8) model, involving a competition between T = 1 and T = 0 pairing. Conclusions similar to those of the SO(5) analysis are reached regarding the importance of four-particle correlations in systems involving neutron-proton pairing.

The development of thymic regulatory T cells (Treg) is mediated by Aire-regulated selfantigen presentation on medullary thymic epithelial cells (mTECs) and dendritic cells (DCs), but the cooperation between these cells is still poorly understood. Here we show that signaling through Toll-like receptors (TLR) expressed on mTECs regulates the production of specific chemokines and other genes associated with post-Aire mTEC development. Using single-cell RNA-sequencing, we identify a new thymic CD14 + Sirpα + population of monocytederived dendritic cells (CD14 + moDC) that are enriched in the thymic medulla and effectively acquire mTEC-derived antigens in response to the above chemokines. Consistently, the cellularity of CD14 + moDC is diminished in mice with MyD88-deficient TECs, in which the frequency and functionality of thymic CD25 + Foxp3 + Tregs are decreased, leading to aggravated mouse experimental colitis. Thus, our findings describe a TLR-dependent function of mTECs for the recruitment of CD14 + moDC, the generation of Tregs, and thereby the establishment of central tolerance.

No abstract

We propose a relationship between thermodynamic phase transitions and ground-state quantum phase transitions in systems with variable Hamiltonian parameters. It is based on a link between zeros of the canonical partition function at complex temperatures and exceptional points of a quantum Hamiltonian in the complex-extended parameter space. This approach is applied in the interacting boson model, where it is shown to properly distinguish the first- and second-order phase transitions.Comment: 14 pages, 5 figure

The identity of peripheral Aire-expressing cells remains poorly understood. This study shows that Aire-expressing cells in peripheral lymph nodes exhibit typical ILC3 characteristics. These cells display potent APC features, suggesting a function in the control of T cell responses.

No abstract

The activity of the Wnt pathway undergoes complex regulation to ensure proper functioning of this principal signaling mechanism during development of adult tissues. The regulation may occur at several levels and includes both positive and negative feedback loops. In the present study we employed one of such negative feedback regulators, naked cuticle homolog 1 (Nkd1), to follow the Wnt pathway activity in the intestine and liver and in neoplasia originated in these organs. Using lineage tracing in transgenic mice we localized Nkd1 mRNA to the bottom parts of the small intestinal crypts and hepatocytes surrounding the central vein of the hepatic lobule. Furthermore, in two mouse models of intestinal tumorigenesis, Nkd1 expression levels were elevated in tumors when compared to healthy tissue. We utilized a collection of human intestinal polyps and carcinomas to confirm that NKD1 represents a robust marker of neoplastic growth. In addition, expression analysis of NKD1 in liver cancer showed that high expression levels of the gene distinguish a subclass of hepatocellular carcinomas related to aberrant Wnt signaling. Finally, our results were confirmed by bioinformatic analysis of large publicly available datasets that included gene expression profiling and high-throughput sequencing data of human colon and liver cancer specimens.