Publications

BACKGROUND

Between 50% and 80% of asthma exacerbations are associated with viral respiratory tract infections (RTIs), yet the influence of viral pathogen diversity on asthma outcomes is poorly understood because of the limited scope and throughput of conventional viral detection methods.

METHODS

We investigated the capability of the Virochip, a DNA microarray-based viral detection platform, to characterize viral diversity in RTIs in adults with and without asthma.

RESULTS

The Virochip detected viruses in a higher proportion of samples (65%) than did culture isolation (17%) while exhibiting high concordance (98%) with and comparable sensitivity (97%) and specificity (98%) to pathogen-specific polymerase chain reaction. A similar spectrum of viruses was identified in the RTIs of each patient subgroup; however, unexpected diversity among human coronaviruses (HCoVs) and human rhinoviruses (HRVs) was revealed. All but one of the HCoVs corresponded to the newly recognized HCoV-NL63 and HCoV-HKU1 viruses, and >20 different serotypes of HRVs were detected, including a set of 5 divergent isolates that formed a distinct genetic subgroup.

CONCLUSIONS

The Virochip can detect both known and novel variants of viral pathogens present in RTIs. Given the diversity detected here, larger-scale studies will be necessary to determine whether particular substrains of viruses confer an elevated risk of asthma exacerbation.

The chemokines CCL21 and CXCL13 are immune factors that dictate homing and motility of lymphocytes and dendritic cells in lymphoid tissues. However, the means by which these chemokines are regulated and how they influence cell trafficking during immune responses remain unclear. We show that CCL21 and CXCL13 are transiently down-regulated within lymphoid tissues during immune responses by a mechanism controlled by the cytokine interferon-gamma. This modulation was found to alter the localization of lymphocytes and dendritic cells within responding lymphoid tissues. As a consequence, priming of T cell responses to a second distinct pathogen after chemokine modulation became impaired. We propose that this transient chemokine modulation may help orchestrate local cellularity, thus minimizing competition for space and resources in activated lymphoid tissues.

Atopic dermatitis (AD) is a chronic dermatosis bearing clinical, histological, and immunologic similarities to chronic allergic contact dermatitis (ACD). AD shows a Th2 cell-dominant inflammatory infiltrate, elevated serum IgE levels, a permeability barrier abnormality, and Staphylococcus aureus colonization. Repeated hapten challenges reportedly produce a Th2-like hypersensitivity reaction (Th2-like HR). Here, 9-10 challenges with oxazolone (Ox) to hairless mice also produced a chronic Th2-like HR. Permeability barrier function and expression of differentiation proteins, filaggrin, loricrin, and involucrin, became abnormal. CRTH-positive Th2-dominant inflammatory infiltrate, with increased IL-4 expression, and a large increase in serum IgE levels were observed. The barrier abnormality was associated with decreased stratum corneum (SC) ceramide content and impaired lamellar body secretion, resulting in abnormal lamellar membranes, as in human AD. Furthermore, as in human AD, epidermal serine protease activity in SC increased and expression of two lamellar body-derived antimicrobial peptides, CRAMP and mBD3, declined after Ox challenges, paralleling the decrease of their human homologues in AD. Thus, multiple Ox challenges to normal murine skin produce a chronic Th2-like HR, with multiple features of human AD. Because of its reproducibility, predictability, and low cost, this model could prove useful for evaluating both pathogenic mechanisms and potential therapies for AD.

The electrophysiological properties of peripheral neurons activated by noxious stimuli, the primary afferent nociceptors, have been investigated intensively, and our knowledge about the molecular basis of transducers for noxious stimuli has increased greatly. In contrast, understanding of the intracellular signaling mechanisms regulating nociceptor sensitization downstream of ligand binding to the receptors is still at a relatively nascent stage. After outlining the initiated signaling cascades, we discuss the emerging plasticity within these cascades and the importance of subcellular compartmentalization. In addition, the recently realized importance of functional interactions with the extracellular matrix, cytoskeleton, intracellular organelles such as mitochondria, and sex hormones will be introduced. This burgeoning literature establishes new cellular features crucial for the function of nociceptive neurons and argues that additional focus should be placed on understanding the complex integration of cellular events that make up the "cell biology of pain."

Estrogen receptor (ER)-alpha mediates estradiol (E(2)) actions in the male gonads and brain and is critical for normal male reproductive function. In the classical pathway, ERalpha binds to estrogen response elements (EREs) to regulate gene transcription. ERalpha can also regulate gene transcription independently of EREs via protein-protein interactions with transcription factors and additionally signal via rapid, nongenomic pathways originating at the cell membrane. This study assessed the degree to which ERE-independent ERalpha signaling can rescue the disrupted masculine sexual behaviors and elevated serum testosterone (T) levels that have been shown to result from ERalpha gene deletion. We utilized male ERalpha null mice that possess a ER knock-in mutation (E207A/G208A; AA), in which the mutant ERalpha is incapable of binding to DNA and can signal only through ERE-independent pathways (ERalpha(-/AA) mice). We found that sexual behavior, including mounting, is virtually absent in ERalpha(-/-) and ERalpha(-/AA) males, suggesting that ERE-independent signaling is insufficient to maintain any degree of normal sexual behavior in the absence of ERE binding. By contrast, ERE-independent signaling in the ERalpha(-/AA) mouse is sufficient to restore serum T levels to values observed in wild-type males. These data indicate that binding of ERs to EREs mediates most if not all of E(2)'s effects on male sexual behavior, whereas ERE-independent ERalpha signaling may mediate E(2)'s inhibitory effects on T production.

Advances in immune assessment, including the development of T-cell receptor excision circle (TREC) assays of thymopoiesis, cytokine-flow cytometry assays of T-cell function, and higher-order phenotyping of T-cell maturation subsets have improved our understanding of T-cell homeostasis. Limited data exist using these methods to characterize immune recovery in adult cord blood (CB) transplant recipients, in whom infection is a leading cause of mortality. We now report the results of a single-center prospective study of T-cell immune recovery after cord blood transplantation (CBT) in a predominantly adult population. Our primary findings include the following: (1) Prolonged T lymphopenia and compensatory expansion of B and natural killer (NK) cells was evident; (2) CB transplant recipients had impaired functional recovery, although we did observe posttransplantation de novo T-cell responses to cytomegalovirus (CMV) in a subset of patients; (3) Thymopoietic failure characterized post-CBT immune reconstitution, in marked contrast to results in other transplant recipients; and (4) Thymopoietic failure was associated with late memory T-cell skewing. Our data suggest that efforts to improve outcomes in adult CB transplant recipients should be aimed at optimizing T-cell immune recovery. Strategies that improve the engraftment of lymphoid precursors, protect the thymus during pretransplant conditioning, and/or augment the recovery of thymopoiesis may improve outcomes after CBT.