No abstract

CD4+ T helper (TH) cells and regulatory T (Treg) cells that respond to common allergens play an important role in driving and dampening airway inflammation in patients with asthma. Until recently, direct, unbiased molecular analysis of allergen-reactive TH and Treg cells has not been possible. To better understand the diversity of these T cell subsets in allergy and asthma, we analyzed the single-cell transcriptome of ~50,000 house dust mite (HDM) allergen–reactive TH cells and Treg cells from asthmatics with HDM allergy and from three control groups: asthmatics without HDM allergy and nonasthmatics with and without HDM allergy. Our analyses show that HDM allergen–reactive TH and Treg cells are highly heterogeneous and certain subsets are quantitatively and qualitatively different in individuals with HDM-reactive asthma. The number of interleukin-9 (IL-9)–expressing HDM-reactive TH cells is greater in asthmatics with HDM allergy compared with nonasthmatics with HDM allergy, and this IL-9–expressing TH subset displays enhanced pathogenic properties. More HDM-reactive TH and Treg cells expressing the interferon response signature (THIFNR and TregIFNR) are present in asthmatics without HDM allergy compared with those with HDM allergy. In cells from these subsets (THIFNR and TregIFNR), expression of TNFSF10 was enriched; its product, tumor necrosis factor–related apoptosis-inducing ligand, dampens activation of TH cells. These findings suggest that the THIFNR and TregIFNR subsets may dampen allergic responses, which may help explain why only some people develop TH2 responses to nearly ubiquitous allergens.

Various subsets of invariant natural killer T (iNKT) cells with different cytokine productions develop in the mouse thymus, but the factors driving their differentiation remain unclear. Here we show that hypomorphic alleles of Zap70 or chemical inhibition of Zap70 catalysis leads to an increase of IFN-γ-producing iNKT cells (NKT1 cells), suggesting that NKT1 cells may require a lower TCR signal threshold. Zap70 mutant mice develop IL-17-dependent arthritis. In a mouse experimental arthritis model, NKT17 cells are increased as the disease progresses, while NKT1 numbers negatively correlates with disease severity, with this protective effect of NKT1 linked to their IFN-γ expression. NKT1 cells are also present in the synovial fluid of arthritis patients. Our data therefore suggest that TCR signal strength during thymic differentiation may influence not only IFN-γ production, but also the protective function of iNKT cells in arthritis.

No abstract

Transcriptomic profiling by RNA sequencing (RNA-Seq) represents the preferred approach to measure genome-wide gene expression for understanding cellular function, tissue development, disease pathogenesis, as well as to identify potential biomarkers and therapeutic targets. For samples with small cell numbers, multiple methods have been described to increase the efficiency of library preparation and to reduce hands-on time and costs. This chapter reviews our approach, which combines flow cytometry and the most recent high-resolution techniques to perform RNA-Seq for samples with low cell numbers as well as for single-cell samples. Our approach reduces technical variability while increasing sensitivity and efficiency. Thus, it is well-suited for large-scale gene expression profiling studies with limited samples for basic and clinical studies.