Individual variation in and lateral asymmetry of mouse epididymal draining lymph nodes.

PROBLEM: Draining lymph nodes (LNs) are pivotal sites for maintaining tolerance to self-antigens as well as eliciting immune responses to exogenous antigens. The epididymis is a male reproductive organ with a unique local immune environment. Although mice are the most commonly used laboratory animals for immunology research, there are no detailed descriptions of the anatomical location and function of LNs that drain the epididymis. METHOD OF STUDY: Evans blue labeling was utilized to explore lymphatic drainage of the epididymis in eight- to ten-week-old male C57BL/6 mice. We confirmed the lymphatic drainage of the epididymis in mice using the objective technique of carboxyfluorescein succinimidyl ester (CFSE)-labeled cells. RESULTS: By combined Evans blue labeling and fluorescent labeling, we found that 1) the patterns of epididymal LN drainage are highly heterogeneous between individual mice; 2) the leftside LNs participate in drainage more frequently than the right-side LNs; and 3) epididymal lymphatic drainage bypasses both the paraaortic and renal LNs in some mice. CONCLUSIONS: These data highlighted the need to consider the individual variation in and lateral asymmetry of draining LNs when characterizing the regional immunology of the mouse epididymis.

Human IFNAR2 Mutant Generated by CRISPR/Cas9-Induced Exon Skipping Upregulates a Subset of Tonic-Like Interferon-Stimulated Genes Upon IFNß Stimulation.

Type I interferons (IFN-Is) play central roles in regulating immune responses. The role of IFNAR2 in IFN-I signaling is an open question since a previous report showed that IFNß was still functional in the absence of IFNAR2 in mice. In this study, we report that IFN-I signaling in human monocyte-derived THP1 cells absolutely depends on IFNAR2, as determined by using a knockout mutant made by CRISPR/Cas9. Additionally, we demonstrated that a 7-bp deletion mutant (Δ7) of IFNAR2 remains responsive to IFNß stimulation and upregulates a subset of interferon-stimulated genes (s-ISGs). The s-ISGs largely overlap with tonic ISGs, which depend on the basal expression level of IFN-I. We also showed that IFN signaling in Δ7 still depends on IFNAR2. Then, we found that the 7-bp deletion in the genome results in the loss of the entire third exon (42 bp) from the mRNA and in the expression of a functionally impaired IFNAR2. These findings clarified the requirement of IFNAR2 for human IFN-I signaling and highlighted that caution should be used with CRISPR/Cas9 technology to prevent misleading interpretations caused by residual protein expression due to exon skipping or other mechanisms.