High-throughput imaging of mRNA at the single-cell level in human primary immune cells

Endogenous glucocorticoids and human immunity: Time to revisit old dogmas

Glucocorticoids (GCs) are steroid hormones with diverse and important roles in the physiologic response to stress. These include permissive and suppressive effects on immunity, which help prepare the organism for future infectious stressors and control the immunological response to a recent stressor, preventing autoimmune damage. The ability of GCs to rapidly suppress an overactive immune system has been harnessed pharmacologically and synthetic GCs have played a central role in the treatment of inflammatory and autoimmune diseases for the past eight decades. Given their importance in clinical medicine, an emphasis on the anti-inflammatory and immunosuppressive effects of synthetic GCs has overshadowed the study of the physiologic roles of endogenous GCs in human immunity. The rising interest in the intersection between neurobiology and immunity, and the development of technologies that facilitate direct experimentation with human cells and tissues, make this an ideal time to critically review existing knowledge on this subject. In this review of the past 100 years of biomedical literature on the effects of endogenous glucocorticoids on human immunity, we summarize existing experimental evidence, reveal key knowledge gaps and misconceptions, and highlight specific areas of opportunity for new research.

hcHCR: High-Throughput Single-Cell Imaging of RNA in Human Primary Immune Cells

Functional genomics and chemical screens can identify and characterize novel cellular factors regulating signaling networks and chemical tools to modulate their function for the treatment of disease. Screening methods have relied primarily on immortalized and/or transformed cancer cell lines, which can limit the generalization of results to more physiologically relevant systems. Most have also relied on immunofluorescence, or on stably expressed recombinant fluorescent proteins, to detect specific protein markers using high-content imaging readouts. In comparison, high-throughput methods to visualize and measure RNA species have been less explored. To address this, we have adapted an isothermal signal amplification chemistry for RNA FISH known as hybridization chain reaction (HCR) to an automated, high-content imaging assay format. We present a detailed protocol for this technique, which we have named high-content HCR (hcHCR). The protocol focuses on the measurement of changes in mRNA abundance at the single-cell level in human primary cells, but it can be applied to a variety of primary cell types and perturbing agents. We anticipate that hcHCR will be most suitable for low- to medium-throughput screening experiments in which changes in transcript abundance are the desired output measure.