Temporal dynamics and genomic programming of plasma cell fates

Affinity-matured plasma cells (PCs) of varying lifespans are generated through a germinal center (GC) response. The developmental dynamics and genomic programs of antigen-specific PC precursors remain to be elucidated. Here, using a model antigen in mice, we demonstrate biphasic generation of PC precursors, with those generating long-lived bone marrow PCs preferentially produced in the late phase of GC response. Clonal tracing using single-cell RNA sequencing and B cell antigen receptor sequencing in spleen and bone marrow compartments, coupled with adoptive transfer experiments, reveals a new PC transition state that gives rise to functionally competent PC precursors. The latter undergo clonal expansion, dependent on inducible expression of TIGIT. We propose a model for the proliferation and programming of precursors of long-lived PCs, based on extended antigen encounters in the GC.

An immunophenotype-coupled transcriptomic atlas of human hematopoietic progenitors

Analysis of the human hematopoietic progenitor compartment is being transformed by single-cell multimodal approaches. Cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) enables coupled surface protein and transcriptome profiling, thereby revealing genomic programs underlying progenitor states. To perform CITE-seq systematically on primary human bone marrow cells, we used titrations with 266 CITE-seq antibodies (antibody-derived tags) and machine learning to optimize a panel of 132 antibodies. Multimodal analysis resolved >80 stem, progenitor, immune, stromal and transitional cells defined by distinctive surface markers and transcriptomes. This dataset enables flow cytometry solutions for in silico-predicted cell states and identifies dozens of cell surface markers consistently detected across donors spanning race and sex. Finally, aligning annotations from this atlas, we nominate normal marrow equivalents for acute myeloid leukemia stem cell populations that differ in clinical response. This atlas serves as an advanced digital resource for hematopoietic progenitor analyses in human health and disease.

Slow cycling and durable Flt3+ progenitors contribute to hematopoiesis under native conditions

The dynamics of the hematopoietic flux responsible for blood cell production in native conditions remains a matter of debate. Using CITE-seq analyses, we uncovered a distinct progenitor population that displays a cell cycle gene signature similar to the one found in quiescent hematopoietic stem cells. We further determined that the CD62L marker can be used to phenotypically enrich this population in the Flt3+ multipotent progenitor (MPP4) compartment. Functional in vitro and in vivo analyses validated the heterogeneity of the MPP4 compartment and established the quiescent/slow-cycling properties of the CD62L- MPP4 cells. Furthermore, studies under native conditions revealed a novel hierarchical organization of the MPP compartments in which quiescent/slow-cycling MPP4 cells sustain a prolonged hematopoietic activity at steady-state while giving rise to other lineage-biased MPP populations. Altogether, our data characterize a durable and productive quiescent/slow-cycling hematopoietic intermediary within the MPP4 compartment and highlight early paths of progenitor differentiation during unperturbed hematopoiesis.

Population-level single-cell genomics reveals conserved gene programs in systemic juvenile idiopathic arthritis

Systemic autoimmune and autoinflammatory diseases are characterized by genetic and cellular heterogeneity. While current single-cell genomics methods provide insights into known disease subtypes, these analysis methods do not readily reveal novel cell-type perturbation programs shared among distinct patient subsets. Here, we performed single-cell RNA-Seq of PBMCs of patients with systemic juvenile idiopathic arthritis (SJIA) with diverse clinical manifestations, including macrophage activation syndrome (MAS) and lung disease (LD). We introduced two new computational frameworks called UDON and SATAY-UDON, which define patient subtypes based on their underlying disrupted cellular programs as well as associated biomarkers or clinical features. Among twelve independently identified subtypes, this analysis uncovered what we believe to be a novel complement and interferon activation program identified in SJIA-LD monocytes. Extending these analyses to adult and pediatric lupus patients found new but also shared disease programs with SJIA, including interferon and complement activation. Finally, supervised comparison of these programs in a compiled single-cell pan-immune atlas of over 1,000 healthy donors found a handful of normal healthy donors with evidence of early inflammatory activation in subsets of monocytes and platelets, nominating possible biomarkers for early disease detection. Thus, integrative pan-immune single-cell analysis resolved what we believe to be new conserved gene programs underlying inflammatory disease pathogenesis and associated complications.

Sinus venosus adaptation models prolonged cardiovascular disease and reveals insights into evolutionary transitions of the vertebrate heart

How two-chambered hearts in basal vertebrates have evolved from single-chamber hearts found in ancestral chordates remains unclear. Here, we show that the teleost sinus venosus (SV) is a chamber-like vessel comprised of an outer layer of smooth muscle cells. We find that in adult zebrafish nr2f1a mutants, which lack atria, the SV comes to physically resemble the thicker bulbus arteriosus (BA) at the arterial pole of the heart through an adaptive, hypertensive response involving smooth muscle proliferation due to aberrant hemodynamic flow. Single cell transcriptomics show that smooth muscle and endothelial cell populations within the adapting SV also take on arterial signatures. Bulk transcriptomics of the blood sinuses flanking the tunicate heart reinforce a model of greater equivalency in ancestral chordate BA and SV precursors. Our data simultaneously reveal that secondary complications from congenital heart defects can develop in adult zebrafish similar to those in humans and that the foundation of equivalency between flanking auxiliary vessels may remain latent within basal vertebrate hearts.

Temporal dynamics and genomic programming of plasma cell fates

Affinity-matured plasma cells (PCs) of varying lifespans are generated through a germinal center (GC) response. The developmental dynamics and genomic programs of antigen-specific PC precursors remain to be elucidated. Using a model antigen, we demonstrate biphasic generation of PC precursors, with those generating long-lived bone marrow PCs preferentially produced in the late phase of GC response. Clonal tracing using scRNA-seq+BCR-seq in spleen and bone marrow compartments, coupled with adoptive transfer experiments, reveal a novel PC transition state that gives rise to functionally competent PC precursors. The latter undergo clonal expansion, dependent on inducible expression of TIGIT. We propose a model for the proliferation and programming of precursors of long-lived PCs, based on extended antigen encounters followed by reduced antigen availability.

Developmental dynamics and genomic programming of GC-derived precursors that give rise to long lived plasma cells

Plasma cell (PC) precursors are generated during a germinal center (GC) response and migrate to the bone marrow (BM) where they undergo terminal differentiation into short-lived (SL) or long-lived (LL) antibody secreting cells. The developmental dynamics and genomic states of PC precursors remain to be elucidated1. We utilize a novel experimental system, involving CD138+ splenocytes isolated from NP-KLH immunized C57Bl/6J mice (21–42 dpi) and their adoptive transfer into B cell deficient mMT mice, to analyze developmental dynamics of antigen-specific PC precursors and their progeny at single-cell resolution. We demonstrate that SLPC precursors are generated earlier (d21), whilst LLPC precursors are generated later (d35) during a GC response. scRNA-seq analyses reveals increased frequency of a novel cluster of transitional cells expressing both B-lineage and plasma cell-specific genes. Coupled analyses using BCR-seq shows that NP-specific transitional cells express cell cycle genes and undergo greater clonal expansion on d35 to give rise to proliferating and quiescent PCs. Antigen-specific clonal tracking in the spleen and BM compartments suggests that the transitional cells emanating from the GC, differentiate into proliferating PCs before migrating to the BM. CITE-seq analyses and reconstitution experiments demonstrate that proliferating PCs are contained within the B220− CD138+ CD44+ CD11a+ subset and are enriched for BMPC precursors. These results reveal novel GC-derived transitional cells that generate precursors of both SLPCs and LLPCs with differing developmental and proliferation dynamics in a humoral immune response.

978 Improving Satisfaction in Patients with Learning Disabilities

Aim

Patients with learning disabilities (LD) are less satisfied because they do not fully understand their surgical management. Poor communication between doctors & LD patients leaves them unhappy & reluctant to seek further help. We aimed to improve satisfaction in 90% of patients.

Method

In one year in a midlands DGH 201 patients with an LD were admitted. Interviews were conducted which highlighted key problems. Multiple ideas were reviewed, and the simple but effective intervention was a brightly coloured prompt sheet with 4 questions placed in the patient notes: Have you explained:

A simple scale tracked the patient & carer satisfaction over 8 weeks as the prompt sheets were introduced to patient notes by the learning disability nurses.

Results

A 90% increase in patient satisfaction was not achieved but considerable positive feedback was. Moreover, the LD nurses witnessed an increased use of hospital passports among doctors as well as improved patient-doctor communication. A small target population restricts the rapid collection of large amounts of data. The patient satisfaction measure was qualitative, and a 10-point scale would have detailed smaller changes. Lack of carer continuity also made it difficult to collect consistent data.

Conclusions

The role of learning disability nurses is key to improving patient understanding and satisfaction, but they can be assisted by channelling and maintaining initiatives to raise awareness of the needs of these patients.

IFN-γ is essential for alveolar macrophage driven pulmonary inflammation in macrophage activation syndrome

Macrophage activation syndrome (MAS) is a life-threatening cytokine storm complicating systemic juvenile idiopathic arthritis (SJIA) driven by IFNγ. SJIA and MAS are associated with an unexplained emerging lung disease (SJIA-LD), with our recent work supporting pulmonary activation of IFNγ pathways pathologically linking SJIA-LD and MAS. Our objective was to mechanistically define the novel observation of pulmonary inflammation in the TLR9 mouse model of MAS. In acute MAS, lungs exhibit mild but diffuse CD4-predominant, perivascular interstitial inflammation with elevated IFNγ, IFN-induced chemokines, and AMΦ expression of IFNγ-induced genes. Single-cell RNA-sequencing confirmed IFN-driven transcriptional changes across lung cell types with myeloid expansion and detection of MAS-specific macrophage populations. Systemic MAS resolution was associated with increased AMΦ and interstitial lymphocytic infiltration. AMΦ transcriptomic analysis confirmed IFNγ-induced proinflammatory polarization during acute MAS, which switches towards an anti-inflammatory phenotype after systemic MAS resolution. Interestingly, recurrent MAS led to increased alveolar inflammation and lung injury, and reset AMΦ polarization towards a proinflammatory state. Furthermore, in mice bearing macrophages insensitive to IFNγ, both systemic feature of MAS and pulmonary inflammation were attenuated. These findings demonstrate that experimental MAS induces IFNγ-driven pulmonary inflammation replicating key features of SJIA-LD, and provides a model system for testing novel treatments directed towards SJIA-LD.

The Rhesus Macaque Serves As a Model for Human Lateral Branch Nephrogenesis

BACKGROUND

Most nephrons are added in late gestation. Truncated extrauterine nephrogenesis in premature infants results in fewer nephrons and significantly increased risk for CKD in adulthood. To overcome the ethical and technical difficulties associated with studies of late-gestation human fetal kidney development, third-trimester rhesus macaques served as a model to understand lateral branch nephrogenesis (LBN) at the molecular level.

METHODS

Immunostaining and 3D rendering assessed morphology. Single-cell (sc) and single-nucleus (sn) RNA-Seq were performed on four cortically enriched fetal rhesus kidneys of 129-131 days gestational age (GA). An integrative bioinformatics strategy was applied across single-cell modalities, species, and time. RNAScope validation studies were performed on human archival tissue.

RESULTS

Third-trimester rhesus kidney undergoes human-like LBN. scRNA-Seq of 23,608 cells revealed 37 transcriptionally distinct cell populations, including naïve nephron progenitor cells (NPCs), with the prior noted marker genes CITED1, MEOX1, and EYA1 (c25). These same populations and markers were reflected in snRNA-Seq of 5972 nuclei. Late-gestation rhesus NPC markers resembled late-gestation murine NPC, whereas early second-trimester human NPC markers aligned to midgestation murine NPCs. New, age-specific rhesus NPCs (SHISA8) and ureteric buds (POU3F4 and TWIST) predicted markers were verified in late-gestation human archival samples.

CONCLUSIONS

Rhesus macaque is the first model of bona fide LBN, enabling molecular studies of late gestation, human-like nephrogenesis. These molecular findings support the hypothesis that aging nephron progenitors have a distinct molecular signature and align to their earlier human counterparts, with unique markers highlighting LBN-specific progenitor maturation.

Diagnostic yield of oesophagogastroduodenoscopy in children with abdominal pain

BACKGROUND

Abdominal pain is the most common indication for oesophagogastroduodenoscopy (OGD) in children. However, existing studies examining the diagnostic outcomes of OGD in children with abdominal pain are limited.

AIM

To examine the diagnostic yield of OGD with biopsy in the evaluation of abdominal pain and to describe the endoscopic and histological findings in patients undergoing OGD for abdominal pain of unclear aetiology.

METHODS

We performed a retrospective cross-sectional cohort study in children under 18 years of age who had OGD for the primary indication of abdominal pain, at Texas Children's Hospital and Children's Hospital of The King's Daughters from 1 January 2002 to 30 June 2005.

RESULTS

Overall, OGD was diagnostic in 454 (38.1%) of the 1191 procedures, including reflux oesophagitis (23%, n = 271), Helicobacter pylori infections (5%, n = 55), peptic ulcers (3%, n = 32), eosinophilic oesophagitis (2%, n = 25), celiac disease (1%, n = 9) and Crohn's disease (0.5%, n = 7). Male gender, older age, elevated C-reactive protein and vomiting were associated with increased diagnostic yield.

CONCLUSIONS

Our findings suggest that OGD is valuable for the evaluation of chronic abdominal pain in children, with a diagnostic yield of 38%. The majority of alarm symptoms and routine laboratory tests are not significantly associated with diagnostic yield.

Synthesis and protein-tyrosine kinase inhibitory activity of polyhydroxylated stilbene analogues of piceatannol

A series of hydroxylated trans-stilbenes related to the antileukemic natural product trans-3,3',4,5'-tetrahydroxystilbene (piceatannol) (1) has been prepared and tested for inhibition of the lymphoid cell lineage-specific protein-tyrosine kinase p56lck, which plays an important role in lymphocyte proliferation and immune function. A number of the analogues displayed enhanced enzyme inhibitory activity relative to the natural product. Reduction of the double bond bridging the two aromatic rings and benzylation of the phenolic hydroxyl groups was found to decrease activity significantly. The most potent compounds in the series proved to be trans-3,3',5,5'-tetrahydroxystilbene, trans-3,3',5-trihydroxystilbene, and trans-3,4,4'-trihydroxystilbene.