Charles David Jones

Conditional Deletion of NF-κB–Inducing Kinase (NIK) in Adult Mice Disrupts Mature B Cell Survival and Activation

NF-κB–inducing kinase (NIK) is a primary regulator of the noncanonical NF-κB signaling pathway, which plays a vital role downstream of BAFF, CD40L, lymphotoxin, and other inflammatory mediators. Germline deletion or inactivation of NIK in mice results in the defective development of B cells and secondary lymphoid organs, but the role of NIK in adult animals has not been studied. To address this, we generated mice containing a conditional allele of NIK. Deletion of NIK in adult mice results in decreases in B cell populations in lymph nodes and spleen, similar to what is observed upon blockade of BAFF. Consistent with this, B cells from mice in which NIK is acutely deleted fail to respond to BAFF stimulation in vitro and in vivo. In addition, mice with induced NIK deletion exhibit a significant decrease in germinal center B cells and serum IgA, which is indicative of roles for NIK in additional pathways beyond BAFF signaling. Our conditional NIK-knockout mice may be broadly useful for assessing the postdevelopmental and cell-specific roles of NIK and the noncanonical NF-κB pathway in mice.

Dendritic cells require NIK for CD40-dependent cross-priming of CD8+ T cells.

Significance The noncanonical NF-κB signaling pathway via the serine kinase NIK (NF-κB–inducing kinase) is essential for normal immune system development and has been implicated in tumor cell survival and growth. Because NIK is under investigation as a therapeutic target, it is important to understand NIK’s role in the context of a fully developed immune system, particularly in regard to mounting adaptive T-cell responses. We have generated and characterized transgenic mice with conditionally deleted NIK in CD11c+ dendritic cells and observe impaired antigen cross-priming of a naive CD8 T-cell response. This defect results from defective antigen cross-presentation by CD8+ dendritic cells and also is associated with their reduced ability to secrete IL-12p40, a cytokine known to promote cross-priming in vivo. Dendritic cells (DCs) link innate and adaptive immunity and use a host of innate immune and inflammatory receptors to respond to pathogens and inflammatory stimuli. Although DC maturation via canonical NF-κB signaling is critical for many of these functions, the role of noncanonical NF-κB signaling via the serine/threonine kinase NIK (NF-κB–inducing kinase) remains unclear. Because NIK-deficient mice lack secondary lymphoid organs, we generated transgenic mice with targeted NIK deletion in CD11c+ cells. Although these mice exhibited normal lymphoid organs, they were defective in cross-priming naive CD8+ T cells following vaccination, even in the presence of anti-CD40 or polyinosinic:polycytidylic acid to induce DC maturation. This impairment reflected two intrinsic defects observed in splenic CD8+ DCs in vitro, namely antigen cross-presentation to CD8+ T cells and secretion of IL-12p40, a cytokine known to promote cross-priming in vivo. In contrast, antigen presentation to CD4+ T cells was not affected. These findings reveal that NIK, and thus probably the noncanonical NF-κB pathway, is critical to allow DCs to acquire the capacity to cross-present antigen and prime CD8 T cells after exposure to licensing stimuli, such as an agonistic anti-CD40 antibody or Toll-like receptor 3 ligand.

Comparison of standard laminectomy with an optimized ejection method for the removal of spinal cords from rats and mice

Abstract For researchers seeking to collect spinal cord samples from mice and rats while avoiding acid decalcification, few options are available. Laminectomy is the standard method which yields high quality samples, yet is time consuming and technically difficult. Ejection of the cord from the vertebral column is another technique commonly used; however, the literature suggests that this method can damage the spinal tissues and is typically avoided when histology of samples is the desired endpoint. Here, we describe an optimized method for ejection of spinal cords from rats and mice, and compare histological quality of these samples with those collected via laminectomy. Our results show that ejection can yield high quality spinal cord samples and may be suitable for use as an alternative to laminectomy.