Opportunities and limitations of B cell depletion approaches in SLE
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Coupling of cell shape, matrix and tissue dynamics ensures embryonic patterning robustness
Tissue patterning coordinates morphogenesis, cell dynamics and fate specification. Understanding how precision in patterning is robustly achieved despite inherent developmental variability during mammalian embryogenesis remains a challenge. Here, based on cell dynamics quantification and simulation, we show how salt-and-pepper epiblast and primitive endoderm (PrE) cells pattern the inner cell mass of mouse blastocysts. Coupling cell fate and dynamics, PrE cells form apical polarity-dependent actin protrusions required for RAC1-dependent migration towards the surface of the fluid cavity, where PrE cells are trapped due to decreased tension. Concomitantly, PrE cells deposit an extracellular matrix gradient, presumably breaking the tissue-level symmetry and collectively guiding their own migration. Tissue size perturbations of mouse embryos and their comparison with monkey and human blastocysts further demonstrate that the fixed proportion of PrE/epiblast cells is optimal with respect to embryo size and tissue geometry and, despite variability, ensures patterning robustness during early mammalian development.
Sensory input, sex and function shape hypothalamic cell type development
Mammalian behaviour and physiology undergo major changes in early life. Young animals rely on conspecifics to meet their needs and start showing nutritional independence and sex-specific social interactions at weaning and puberty, respectively. How neuronal populations regulating homeostatic functions and social behaviours develop during these transitions remains unclear. We used paired transcriptomic and chromatin accessibility profiling to examine the developmental trajectories of neuronal populations in the hypothalamic preoptic region, where cell types with key roles in physiological and behavioural control have been identified1,2,3,4,5,6. These data show a marked diversity of developmental trajectories shaped by the sex of the animal, and the location and behavioural or physiological function of the corresponding cell types. We identify key stages of preoptic development, including early diversification, perinatal emergence of sex differences, postnatal maturation and refinement of signalling networks, and nonlinear transcriptional changes accelerating at the time of weaning and puberty. We assessed preoptic development in various sensory mutants and find a major role for vomeronasal sensing in the timing of preoptic cell type maturation. These results provide new insights into the development of neurons controlling homeostatic functions and social behaviours and lay ground for examining the dynamics of these functions in early life.
Integrating single-cell RNA and T cell/B cell receptor sequencing with mass cytometry reveals dynamic trajectories of human peripheral immune cells from birth to old age
A comprehensive understanding of the evolution of the immune landscape in humans across the entire lifespan at single-cell transcriptional and protein levels, during development, maturation and senescence is currently lacking. We recruited a total of 220 healthy volunteers from the Shanghai Pudong Cohort (NCT05206643), spanning 13 age groups from 0 to over 90 years, and profiled their peripheral immune cells through single-cell RNA-sequencing coupled with single T cell and B cell receptor sequencing, high-throughput mass cytometry, bulk RNA-sequencing and flow cytometry validation experiments. We revealed that T cells were the most strongly affected by age and experienced the most intensive rewiring in cell–cell interactions during specific age. Different T cell subsets displayed different aging patterns in both transcriptomes and immune repertoires; examples included GNLY+CD8+ effector memory T cells, which exhibited the highest clonal expansion among all T cell subsets and displayed distinct functional signatures in children and the elderly; and CD8+ MAIT cells, which reached their peaks of relative abundance, clonal diversity and antibacterial capability in adolescents and then gradually tapered off. Interestingly, we identified and experimentally verified a previously unrecognized ‘cytotoxic’ B cell subset that was enriched in children. Finally, an immune age prediction model was developed based on lifecycle-wide single-cell data that can evaluate the immune status of healthy individuals and identify those with disturbed immune functions. Our work provides both valuable insights and resources for further understanding the aging of the immune system across the whole human lifespan.
Syk inhibitor attenuates lupus in FcγRIIb−/− mice through the Inhibition of DNA extracellular traps from macrophages and neutrophils via p38MAPK-dependent pathway
Spleen tyrosine kinase (Syk), an important hub of immune signaling, is activated by several signalings in active lupus which could be interfered by Syk inhibitor but is still not completely evaluated in innate immune cells associated with lupus activity. Hence, a Syk inhibitor (fostamatinib; R788) was tested in vivo using Fc gamma receptor-deficient (FcγRIIb−/−) lupus mice and in vitro (macrophages and neutrophils). After 4 weeks of oral Syk inhibitor, 40 week-old FcγRIIb−/− mice (a full-blown lupus model) demonstrated less prominent lupus parameters (serum anti-dsDNA, proteinuria, and glomerulonephritis), systemic inflammation, as evaluated by serum TNFa, IL-6, and citrullinated histone H3 (CitH3), gut permeability defect, as indicated by serum FITC dextran assay, serum lipopolysaccharide (LPS), and serum (1 → 3)-β-D-glucan (BG), extracellular traps (ETs) and immune complex deposition in spleens and kidneys (immunofluorescent staining of CitH3 and immunoglobulin G) than FcγRIIb−/− mice with placebo. Due to the spontaneous elevation of LPS and BG in serum, LPS plus BG (LPS + BG) was used to activate macrophages and neutrophils. After LPS + BG stimulation, FcγRIIb−/− macrophages and neutrophils demonstrated predominant abundance of phosphorylated Syk (Western blotting), and the pro-inflammatory responses (CD86 flow cytometry analysis, supernatant cytokines, ETs immunofluorescent, and flow cytometry-based apoptosis). With RNA sequencing analysis and western blotting, the Syk-p38MAPK-dependent pathway was suggested as downregulating several inflammatory pathways in LPS + BG-activated FcγRIIb−/− macrophages and neutrophils. Although both inhibitors against Syk and p38MAPK attenuated macrophage and neutrophil inflammatory responses against LPS + WGP, the apoptosis inhibition by p38MAPK inhibitor was not observed. These results suggested that Syk inhibitor (fostamatinib) improved the severity of lupus caused by FcγRIIb defect partly through Syk-p38MAPK anti-inflammation that inhibited both ET formation and cytokine production from innate immune cells.
Cell-associated galectin 9 interacts with cytotoxic T cells confers resistance to tumor killing in nasopharyngeal carcinoma through autophagy activation
Immune effector cells, including cytotoxic T lymphocytes (CTLs) play essential roles in eliminating cancer cells. However, their functionality is often compromised, even when they infiltrate the tumor microenvironment (TME) or are transferred to cancer patients adoptively. In this study, we focused on galectin 9 (G9), an inhibitory ligand that we observed to be predominately positioned on the plasma membrane and readily interacts with CD8 + CTL in the TME of nasopharyngeal carcinoma (NPC). We discovered that cell-cell contact between activated effector CTLs and target tumor cells (TarTC) with G9 overexpression led to cellular death defects. Despite the formation of CTL–TarTC conjugates, there is no impact on the cell number nor viability of CTL, and the release of cytolytic content and associated activity were not completely abrogated. Instead, this interaction promoted autophagy and restricted necrosis in the TarTC. Furthermore, reducing G9 expression in tumor cells enhanced the suppressive effect on tumor growth upon adoptive transfer of activated effector CTL. Additionally, inhibiting autophagy effectively controlled tumor growth in cases of G9 overexpression. Therefore, we highlight the contribution of G9 in facilitating the resistance of NPC to CTL-mediated killing by inducing a selection-cell death state in tumor cells, characterized by increased autophagy and decreased necrosis.
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