PARP9-DTX3L ubiquitin ligase targets host histone H2BJ and viral 3C protease to enhance interferon signaling and control viral infection.

Enhancing the response to interferon could offer an immunological advantage to the host. In support of this concept, we used a modified form of the transcription factor STAT1 to achieve hyper-responsiveness to interferon without toxicity and markedly improve antiviral function in transgenic mice and transduced human cells. We found that the improvement depended on expression of a PARP9-DTX3L complex with distinct domains for interaction with STAT1 and for activity as an E3 ubiquitin ligase that acted on host histone H2BJ to promote interferon-stimulated gene expression and on viral 3C proteases to degrade these proteases via the immunoproteasome. Thus, PARP9-DTX3L acted on host and pathogen to achieve a double layer of immunity within a safe reserve in the interferon signaling pathway.

Macrophage chitinase 1 stratifies chronic obstructive lung disease.

Diagnosis and therapy of chronic inflammatory lung disease is limited by the need for individualized biomarkers that provide insight into pathogenesis. Herein we show that mouse models of chronic obstructive lung disease exhibit an increase in lung chitinase production but cannot predict which chitinase family member may be equivalently increased in humans with corresponding lung disease. Moreover, we demonstrate that lung macrophage production of chitinase 1 is selectively increased in a subset of subjects with severe chronic obstructive pulmonary disease, and this increase is reflected in plasma levels. The findings provide a means to noninvasively track alternatively activated macrophages in chronic lung disease and thereby better differentiate molecular phenotypes in heterogeneous patient populations.

IL-12 p80-dependent macrophage recruitment primes the host for increased survival following a lethal respiratory viral infection.

A protective immune response to a respiratory viral infection requires a series of coordinated cellular and molecular responses. We have previously demonstrated that increased expression of airway epithelial cell interleukin (IL)-12 p80, a macrophage chemoattractant, is associated with human respiratory viral infection and mediates post-viral mortality in the mouse. To better understand the role of IL-12 p80-dependent macrophage chemotaxis in mediating viral immunity, we generated a transgenic mouse strain utilizing a promoter to drive IL-12 p40 gene expression in the airway epithelium. This transgenic strain secreted biologically active IL-12 p80 in a lung-specific manner, and demonstrated a selective increase in the number of resident, unactivated airway macrophages at baseline. Following infection with a sublethal dose of mouse parainfluenza virus type 1 (Sendai virus), the transgenic mice demonstrated an earlier peak and decline in the number of airway inflammatory cells. The transgenic mice were resistant to a lethal dose of virus and this viral resistance was dependent on the increased number of airway macrophages at baseline as partial depletion prior to infection abrogated this phenotype. The survival advantage in the transgenic mice was independent of viral load but was associated with a more rapid decline in the number of airway inflammatory cells and concentrations of multiple chemokines including the CC chemokine ligand 2 (CCL2)/JE, CCL3/macrophage inflammatory protein (MIP)-1alpha, CCL4/MIP-1beta, and CCL5/RANTES. Collectively, these results suggest that IL-12 p80-driven increases in the number of resident airway macrophages prime the host for a protective immune response that can confer increased survival following a lethal respiratory viral infection.

Persistent activation of an innate immune response translates respiratory viral infection into chronic lung disease.

To understand the pathogenesis of chronic inflammatory disease, we analyzed an experimental mouse model of chronic lung disease with pathology that resembles asthma and chronic obstructive pulmonary disease (COPD) in humans. In this model, chronic lung disease develops after an infection with a common type of respiratory virus is cleared to only trace levels of noninfectious virus. Chronic inflammatory disease is generally thought to depend on an altered adaptive immune response. However, here we find that this type of disease arises independently of an adaptive immune response and is driven instead by interleukin-13 produced by macrophages that have been stimulated by CD1d-dependent T cell receptor-invariant natural killer T (NKT) cells. This innate immune axis is also activated in the lungs of humans with chronic airway disease due to asthma or COPD. These findings provide new insight into the pathogenesis of chronic inflammatory disease with the discovery that the transition from respiratory viral infection into chronic lung disease requires persistent activation of a previously undescribed NKT cell-macrophage innate immune axis.

Gene expression in pharyngeal arch 1 during human embryonic development.

Craniofacial abnormalities are one of the most common birth defects in humans, but little is known about the human genes that control these important developmental processes. To identify relevant genes, we analyzed transcription profiles of human pharyngeal arch 1 (PA1), a conserved embryonic structure that develops into the palate and jaw. Using microdissected, normal human craniofacial structures, we constructed 12 SAGE (serial analysis of gene expression) libraries and sequenced 606 532 tags. We also performed Affymetrix microarray analysis on 25 craniofacial targets. Our data revealed not only genes "enriched" or differentially expressed in PA1 during fourth and fifth week of human development, but also 6927 genes newly identified to be expressed in human PA1. Many of these genes are involved in biosynthetic processes and have binding function and catalytic activity. We compared expression profiles of human genes with those of mouse homologs to look for genes more specific to human craniofacial development and found 766 genes expressed in human PA1, but not in mouse PA1. We also identified 1408 genes that were expressed in mouse as well as human PA1 and could be useful in creating mouse models for human conditions. We confirmed conservation of some human PA1 expression patterns in mouse embryonic samples with whole mount in situ hybridization and real-time RT-PCR. This comprehensive approach to expression profiling gives insights into the early development of the craniofacial region and provides markers for developmental structures and candidate genes, including SET and CCT3, for diseases such as orofacial clefting and micrognathia.