Generation of mature T cells from human hematopoietic stem and progenitor cells in artificial thymic organoids

Studies of human T cell development require robust model systems that recapitulate the full span of thymopoiesis, from hematopoietic stem and progenitor cells (HSPCs) through to mature T cells. Existing in vitro models induce T cell commitment from human HSPCs; however, differentiation into mature CD3+TCRab+ single positive (SP) CD8+ or CD4+ cells is limited. We describe here a serum-free, artificial thymic organoid (ATO) system that supports highly efficient and reproducible in vitro differentiation and positive selection of conventional human T cells from all sources of HSPCs. ATO-derived T cells exhibited mature naïve phenotypes, a diverse TCR repertoire, and TCR-dependent function. ATOs initiated with TCR-engineered HSPCs produced T cells with antigen specific cytotoxicity and near complete lack of endogenous TCR Vβ expression, consistent with allelic exclusion of Vβ loci. ATOs provide a robust tool for studying human T cell development and stem cell based approaches to engineered T cell therapies.

Comparative efficacy, persistent effect, and treatment intervals of anthelmintic pastes in naturally infected horses

Eighty horses were involved in a comparative, controlled, and randomised field study conducted in Australia and Brazil. This study was undertaken to address the duration of efficacy (by faecal egg count reduction) of four anthelmintic pastes and to measure the time required between treatments on horses naturally infected by gastrointestinal nematodes. The treatment interval was based on the egg reappearance period (ERP), defined as "the period after treatment when horses have reached a positive egg count equal or superior to 200 eggs per gram (epg) of faeces". Horses were ranked according to pre-treatment faecal egg counts and randomly allocated on Day 0 to one of the four treatment groups (n=16). Group A received a combination of ivermectin at 200 microg/kg and praziquantel at 1.5mg/kg, Group B received an ivermectin paste at 200 microg/kg, Group C received a reference product containing ivermectin at 200 microg/kg, Group D received a moxidectin paste at 400 microg/kg, and Group E received a placebo. Horses were individually faecal sampled at weekly interval from Days 0 to 70 after treatment and coprocultures were made on pooled samples at the pre-treatment time on D-7 in Brazil and D-6 in Australia. The nematode population was mainly composed of small strongyles (Cyathostominae, Gyalocephalus spp., Triodontophorus spp.). All products were efficient (>90% efficacy) until Day 42 with no statistical difference between groups. From Day 49 onwards, Group C reached the threshold, while Group B exceeded this threshold on Day 56. Groups A and D remained below 200 epg for the entire study period (70 days). The interval between two anthelmintic treatments can vary according to the threshold. The ERP was defined as the period after treatment while the output of eggs is negligible or considered as acceptable. The mean number of days calculated to recurrence of 200 epg and more was, respectively, 60 days for product A, 56 days for products B and C, and 64 days for product D. If treatments are combined with other methods of limiting exposure to infective larvae on pasture, the number of treatments required will be reduced even further.

In Vitro Recapitulation of Murine Thymopoiesis from Single Hematopoietic Stem Cells

We report a serum-free, 3D murine artificial thymic organoid (M-ATO) system that mimics normal murine thymopoiesis with the production of all T cell stages, from early thymic progenitors to functional single-positive (CD8SP and CD4SP) TCRαβ and TCRγδ cells. RNA sequencing aligns M-ATO-derived populations with phenotypically identical primary thymocytes. M-ATOs initiated with Rag1-/- marrow produce the same differentiation block as seen in the endogenous thymus, and Notch signaling patterns in M-ATOs mirror primary thymopoiesis. M-ATOs initiated with defined hematopoietic stem cells (HSCs) and lymphoid progenitors from marrow and thymus generate each of the downstream differentiation stages, allowing the kinetics of T cell differentiation to be tracked. Remarkably, single HSCs deposited into each M-ATO generate the complete trajectory of T cell differentiation, producing diverse TCR repertoires across clones that largely match endogenous thymus. M-ATOs represent a highly reproducible and efficient experimental platform for the interrogation of clonal thymopoiesis from HSCs.

The efficacy of injectable and pour-on formulations of moxidectin against lice on cattle

The efficacy of one administration of moxidectin against natural infestations of the 3 common species of cattle lice in Australia: Linognathus vituli, Damalinia bovis and Haematopinus eurysternus, was determined. A high degree of control of L vituli (the long-nosed sucking louse) was achieved with both the cattle injection (96.7% and 100%) at 0.2 mg/kg and the cattle pour-on formulation (94.6% and 100%) at 0.5 mg/kg on the 2 farms where this louse occurred. An injection of moxidectin at 0.2 mg/kg did not eliminate D bovis. In these trials efficacy ranged from nil to 85.2%. In contrast the pour-on formulation at 0.5 mg/kg provided consistently high efficacy (83.6 to 100%) against D bovis on 3 farms. Infestations of H eurysternus (the short-nosed sucking louse) were low and no significant difference was recorded between treatment groups in a single trial, however, lice persisted on 3 to 7 cattle in the untreated group at each inspection, whereas none were found on any animals in the 2 groups treated with moxidectin on inspection after treatment.

Antitrust aspects of exclusive contracts in medical imaging

Exclusive contracts between radiologists and hospitals may be more frequently scrutinized for antitrust violations because of the Hyde v Jefferson Parish Hospital District No. 2 case. In the Hyde case, the lower court decided antitrust law had been violated, and it was the first antitrust case about exclusive medical contracts to be reviewed by the U.S. Supreme Court. The case is a precedent for considering similar circumstances according to traditional business antitrust analyses such as per se violations, tying arrangements, group boycott, and market foreclosure. Areas that may be scrutinized for anticompetitiveness include hospital privileges when radiologists have exclusive contracts with the community's only hospital or provide services unique within an area, and physicians' access to scarce resources (e.g., computed tomography [CT], magnetic resonance [MR] imaging). Radiologists must understand antitrust implications of their hospital contracts; examine the terms of staff appointment, bylaws, and rights; and be able to guide their attorneys through contract negotiations.

Pleiotropic Roles of VEGF in the Microenvironment of the Developing Thymus

Neonatal life marks the apogee of murine thymic growth. Over the first few days after birth, growth slows and the murine thymus switches from fetal to adult morphology and function; little is known about the cues driving this dramatic transition. In this study, we show for the first time (to our knowledge) the critical role of vascular endothelial growth factor (VEGF) on thymic morphogenesis beyond its well-known role in angiogenesis. During a brief window a few days after birth, VEGF inhibition induced rapid and profound remodeling of the endothelial, mesenchymal and epithelial thymic stromal compartments, mimicking changes seen during early adult maturation. Rapid transcriptional changes were seen in each compartment after VEGF inhibition, including genes involved in migration, chemotaxis, and cell adhesion as well as induction of a proinflammatory and proadipogenic signature in endothelium, pericytes, and mesenchyme. Thymocyte numbers fell subsequent to the stromal changes. Expression patterns and functional blockade of the receptors VEGFR2 and NRP1 demonstrated that VEGF mediates its pleiotropic effects through distinct receptors on each microenvironmental compartment of the developing mouse thymus.

Synovial immunoglobulin and antibody in vaccinated and nonvaccinated calves challenged with Mycoplasma bovis

Intravenous injection of Mycoplasma bovis produced in calves arthritis with synovial infiltration of lymphocytes, macrophages and neutrophils. Necrosis was observed focally around blood vessels. Joint spaces contained fibrinopurulent exudate. Parenterally vaccinated calves had a markedly reduced frequency of arthritic joints. Immunoglobulin classes and specific antibody in joint fluids were quantitatively less than in sera but significantly greater in arthritic than in normal joints. The possible mechanisms of induction of joint fluid antibody are discussed.

Multi-Omics Atlas-Assisted Discovery of Transcription Factors for Selective T Cell State Programming

Transcription factors (TFs) regulate the differentiation of T cells into diverse states with distinct functionalities. To precisely program desired T cell states in viral infections and cancers, we generated a comprehensive transcriptional and epigenetic atlas of nine CD8 + T cell differentiation states for TF activity prediction. Our analysis catalogued TF activity fingerprints of each state, uncovering new regulatory mechanisms that govern selective cell state differentiation. Leveraging this platform, we focused on two critical T cell states in tumor and virus control: terminally exhausted T cells (TEX term ), which are dysfunctional, and tissue-resident memory T cells (T RM ), which are protective. Despite their functional differences, these states share significant transcriptional and anatomical similarities, making it both challenging and essential to engineer T cells that avoid TEX term differentiation while preserving beneficial T RM characteristics. Through in vivo CRISPR screening combined with single-cell RNA sequencing (Perturb-seq), we validated the specific TFs driving the TEX term state and confirmed the accuracy of TF specificity predictions. Importantly, we discovered novel TEX term -specific TFs such as ZSCAN20, JDP2, and ZFP324. The deletion of these TEX term -specific TFs in T cells enhanced tumor control and synergized with immune checkpoint blockade. Additionally, this study identified multi-state TFs like HIC1 and GFI1, which are vital for both TEX term and T RM states. Furthermore, our global TF community analysis and Perturb-seq experiments revealed how TFs differentially regulate key processes in T RM and TEX term cells, uncovering new biological pathways like protein catabolism that are specifically linked to TEX term differentiation. In summary, our platform systematically identifies TF programs across diverse T cell states, facilitating the engineering of specific T cell states to improve tumor control and providing insights into the cellular mechanisms underlying their functional disparities.