Morbidity and mortality in cystic fibrosis (CF) are due not only to abnormal epithelial cell function, but also to an abnormal immune response. We have shown previously that macrophages lacking CFTR, the gene mutated in CF, contribute significantly to the hyper-inflammatory response observed in CF. Here we show for the first time that lack of functional CFTR in murine macrophages causes abnormal Toll like receptor (TLR) 4 subcellular localization. Upon LPS stimulation, CFTR macrophages have prolonged TLR4 retention in the early endosome and reduced translocation into the lysosomal compartment. This abnormal TLR4 trafficking leads to increased LPS-induced activation of the NF-kB, MAPK and IRF-3 pathways, and to decreased TLR4 degradation, which affects downregulation of the proinflammatory state. In addition to primary murine cells, mononuclear cells isolated from CF patients demonstrate similar defects in response to LPS. Moreover, specific inhibition of CFTR function induces abnormal TLR4 trafficking and enhances the inflammatory response of wildtype murine cells to LPS. Thus, functional CFTR in macrophages influences the physiological TLR4 spatial and temporal localization and perturbs LPS-mediated signaling in both murine CF models and patients with CF.

Reading disability (RD) or dyslexia is a common neurogenetic disorder. Two genes, KIAA0319 and DCDC2, have been identified by association studies of the DYX2 locus on 6p21.3. We previously identified a 2445 bp deletion, and a compound STR within the deleted region (BV677278), in intron 2 of DCDC2. The deletion and several alleles of the STR are strongly associated with RD (P = 0.00002). In this study we investigated whether BV677278 is a regulatory region for DCDC2 by electrophoretic mobility shift and luciferase reporter assays. We show that oligonucleotide probes from the STR bind nuclear protein from human brain, and that alleles of the STR have a range of DCDC2-specific enhancer activities. Five alleles displayed strong enhancer activity and increased gene expression, while allele 1 showed no enhancer activity. These studies suggest that the association of BV677278 with RD reflects a role as a modifier of DCDC2 expression.

Hex is a homeobox gene that is expressed in all stages of B cell development except plasma cells. We studied lymphocyte development in the absence of Hex by using the RAG1-deficient blastocyst complementation system because homozygous disruption of Hex is embryonic lethal. Hex ؊/؊ ;RAG1 ؊/؊ chimeric mice had severely reduced numbers of mature B cells, pre-B cells, and CD5 ؉ B cells with a striking 15-fold increase in the percentage of B220 ؊ CD19 ؉ cells in the bone marrow. Hex ؊/؊ ;RAG1 ؊/؊ chimeric mice failed to generate IgG antibodies to T cell-independent antigens, although their serum IgM levels and antibody responses to T cell-dependent antigens were intact. Therefore, Hex is necessary for B cell development and function and its absence results in a dramatic increase in B220 ؊ CD19 ؉ cells.

Cystic fibrosis (CF) is caused by homozygous mutations of the CF transmembrane conductance regulator (CFTR) Cl− channel, which result in chronic pulmonary infection and inflammation, the major cause of morbidity and mortality. Although these processes are clearly related to each other, each is likely to contribute to the pathology differently. Understanding the contribution of each of these processes to the overall pathology has been difficult, because they are usually so intimately connected. Various CF mouse models have demonstrated abnormal immune responses compared with wild-type (WT) littermates when challenged with live bacteria or bacterial products acutely. However, these studies have not investigated the consequences of persistent inflammation on lung tissue in CF mice, which may better model the lung pathology in patients. We characterized the lung pathology and immune response of Cftr−/− (CF) and Cftr+/+ (WT) mice to chronic administration of Pseudomonas aeruginosa lipopolysaccharide (LPS). We show that, after long-term repeated LPS exposure, CF mice develop an abnormal and persistent immune response, which is associated with more robust structural changes in the lung than those observed in WT mice. Although CF mice and their WT littermates develop lung pathology after chronic exposure to LPS, the inflammation and damage resolve in WT mice. However, CF mice do not recover efficiently, and, as a consequence of their chronic inflammation, CF mice are more susceptible to morphological changes and lung remodeling. This study shows that chronic inflammation alone contributes significantly to aspects of CF lung pathology.