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Michael J Holtzman

Publications and source records attributed to Michael J Holtzman.

31 records · Page 2Linked to original sources
PubMed2004

"Hit-and-run" effects of paramyxoviruses as a basis for chronic respiratory disease.

BACKGROUND: The traditional scheme for asthma pathogenesis depends on increased T helper type 2 (Th2) over T helper type 1 (Th1) responses to allergic and nonallergic stimuli and consequent airway inflammation, hyperreactivity and hypersecretion. Here we question whether the innate immune system, including airway epithelial cells, and the adaptive one may manifest an aberrant antiviral response as an additional basis for chronic inflammatory diseases, including asthma. METHODS: We focused on the signal transduction and genetic basis for mucosal immunity, inflammation and remodeling, especially in relation to airway diseases. We concentrated on the response to paramyxoviruses because these agents are closely associated with common acute and chronic airway diseases. We used viral, cellular and mouse models, as well as human subjects, for study and made comparisons among these systems. Our approach aims to answer 2 major questions: (1) what are the factors that control acute paramyxoviral infection; and (2) how can these transient infections cause long term airway disease? CONCLUSIONS: Our studies show that antiviral defense depends on a special network of epithelial immune response genes that signal to the adaptive immune system. Viruses ordinarily trigger this network, but it is also permanently activated in asthma, even in the absence of viral infection. In addition, we find that, in susceptible genetic backgrounds, respiratory viruses cause a "hit-and-run" phenomenon indicated by the development of an asthmatic phenotype long after the infection has cleared. On the basis of this information, we developed a new scheme for asthma pathogenesis that includes epithelial, viral and allergic components and allows viral reprogramming of host behavior.

Animals↗
PubMed2004

Differential role of Janus family kinases (JAKs) in interferon-gamma-induced lung epithelial ICAM-1 expression: involving protein interactions between JAKs, phospholipase Cgamma, c-Src, and STAT1.

The signaling pathway for IFN-gamma-mediated induction of ICAM-1 expression was further studied in human NCI-H292 epithelial cells. The Tyr701 phosphorylation of signal transducer and activator of transcription 1 (STAT1) induced by interferon-gamma (IFN-gamma) and 12-O-tetradecanoylphorbol 13-acetate (TPA) was inhibited by the protein kinase C (PKC) inhibitor staurosporine, the tyrosine kinase inhibitor herbimycin, or the Src kinase inhibitor PP2. An association between c-Src and STAT1 was increased by IFN-gamma and TPA, indicating the direct phosphorylation of STAT1 by PKC-dependent c-Src activation. Tyrosine phosphorylation of Janus kinases (JAK) 1/2 was induced by IFN-gamma but not by TPA. In addition, ICAM-1 promoter activity induced by IFN-gamma, but not that induced by TPA, was inhibited by the dominant-negative JAK1 and JAK2 mutants. IFN-gamma-induced tyrosine phosphorylation of phospholipase C (PLC)-gamma was inhibited by AG 490 (a JAK inhibitor), and the association between JAK1/2 and PLC-gamma was increased after IFN-gamma treatment, indicating the activation of PLC-gamma via JAK1/2 phosphorylation. ICAM-1 promoter activities induced by the overexpression of wild-type JAK1- and PLC-gamma2 were blocked by the PLCgamma2 mutant or the dominant-negative PKCalpha (Lys-->Arg), c-Src (Lys-->Met), or STAT1 (Y701M) mutants, but not by dominant-negative STAT3 (DN) mutants. These results confirmed that IFN-gamma activated PLC-gamma via JAK1/2 phosphorylation to induce PKC, c-Src, STAT1 activation, and ICAM-1 expression. The association between JAK1/2 and STAT1 was increased by IFN-gamma but not by TPA. It was inhibited by AG 490 but not by U73122, indicating the possible involvement of the JAK1/2-STAT1 pathway. All the results show that IFN-gamma induces ICAM-1 expression by two different pathways in NCI-H292 epithelial cells. One is the JAK1/2-dependent PLC-gamma pathway inducing the activations of PKCalpha, c-Src, and STAT1, and the other is the direct activation of STAT1 by JAK1/2.

DNA-Binding Proteins↗
PubMed2003

Intravital microscopy comparing T lymphocyte trafficking to the spleen and the mesenteric lymph node.

Lymphocyte rolling velocity is determined largely by interactions between leukocyte alpha(4)-integrin (CD49d) and L-selectin and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in mesenteric postcapillary venules and Peyer's patch high endothelial venules (HEVs). The role of these interactions in other tissue sites of lymphocyte emigration is not known. With the use of real-time intravital confocal microscopy, we found that rolling velocities of T lymphocytes in the murine mesenteric lymph node (MLN) HEV also depend on L-selectin and CD49d. However, in the murine spleen, rolling velocities of T lymphocytes are not influenced by the loss of L-selectin and CD49d. With the use of FITC-dextran and TIE2-GFP mice, we further defined the microvascular compartments of the spleen and showed that adherence of T cells is localized to regions in the white pulp that are not lined by endothelial cells and have shear rates similar to bone marrow sinusoids. These results establish that T cell trafficking to the spleen differs from trafficking to other secondary lymphoid organs and suggest that the mechanical properties of the blood-filtering role of the spleen are important in T cell accumulation in the organ.

Animals↗
PubMed2003

Drug development for asthma.

Asthma is characterized by abnormal immune cell accumulation and activation in the airways as well as dysfunction of specialized parenchymal cells. Research strategies to define asthma pathogenesis have focused on the hypothesis that this altered state is a consequence of an excessive allergen-driven response. Drug development for asthma has been directed at improving existing agents and expanding new modalities that target the Th2 allergic cascade. Significant opportunities are being pursued in each of these areas. However, this strategy may not account for some critical aspects of asthma pathogenesis. Alternative considerations include the need for a multidisciplinary approach to dissect the complexity of the asthma phenotype as well as a better understanding of nonallergic factors (especially viral reprogramming of airway behavior) in the development of the phenotype. Each of these considerations may provide an alternative strategy for further drug development for asthma and other complex diseases.

Anti-Inflammatory Agents↗
PubMed2002

Antigen-nonspecific recruitment of Th2 cells to the lung as a mechanism for viral infection-induced allergic asthma.

Respiratory viral infections have been shown to trigger exacerbations of asthma; however, the mechanism by which viral Th1-type inflammation exacerbates an allergic Th2-type disease remains unclear. We have previously shown that although adoptively transferred Th2 cells are inefficiently recruited to the lung in response to Ag, cotransfer of Th1 cells can increase accumulation of Th2 cells. In this study, we show that respiratory viral infection increases recruitment of resting Th2 cells specific for OVA even in the absence of OVA challenge. These findings suggest that the mechanism by which Th1-type inflammation enhances allergy is via an effect on recruitment. To study the role of the antigenic specificity of Th1 cells in the enhancement of Th2 cell recruitment and to determine whether virus-induced recruitment of OVA-specific Th2 cells may involve Th1 cells specific to a different Ag, we tested whether hen egg lysozyme-specific Th1 cells could synergize with OVA-specific Th2 cells. Challenge of mice that had received adoptively transferred Th1 cells plus Th2 cells induced the expression of inflammatory chemokines in the lung and increased both recruitment and activation of Th2 cells, leading to eosinophil recruitment, even in the absence of challenge with the Th2 Ag. Interestingly, as IL-5 supports eosinophilia, culture of resting Th2 cells with fresh APC induced production of IL-5 in the absence of specific Ag. Thus, Ag-specific activation of Th1 cells enhances the recruitment potential of the lung leading to recruitment and activation of Th2 cells. This implies that circulating Th2 cells in allergic individuals could enter the lungs in response to infection or inflammation and become activated to trigger allergy.

Animals↗
PubMed2002

Immunity, inflammation, and remodeling in the airway epithelial barrier: epithelial-viral-allergic paradigm.

The concept that airway inflammation leads to airway disease has led to a widening search for the types of cellular and molecular interactions responsible for linking the initial stimulus to the final abnormality in airway function. It has not yet been possible to integrate all of this information into a single model for the development of airway inflammation and remodeling, but a useful framework has been based on the behavior of the adaptive immune system. In that paradigm, an exaggeration of T-helper type 2 (Th2) over Th1 responses to allergic and nonallergic stimuli leads to airway inflammatory disease, especially asthma. In this review, we summarize alternative evidence that the innate immune system, typified by actions of airway epithelial cells and macrophages, may also be specially programmed for antiviral defense and abnormally programmed in inflammatory disease. Furthermore, this abnormality may be inducible by paramyxoviral infection and, in the proper genetic background, may persist indefinitely. Taken together, we propose a new model that highlights specific interactions between epithelial, viral, and allergic components and so better explains the basis for airway immunity, inflammation, and remodeling in response to viral infection and the development of long-term disease phenotypes typical of asthma and other hypersecretory airway diseases.

Animals↗
PubMed2002

Viral induction of a chronic asthma phenotype and genetic segregation from the acute response.

Paramyxoviral infections cause most of the acute lower respiratory tract illness in infants and young children and predispose to the development of chronic wheezing, but the relationship between these short- and long-term viral effects are uncertain. Here we show that a single paramyxoviral infection of mice (C57BL6/J strain) not only produces acute bronchiolitis, but also triggers a chronic response with airway hyperreactivity and goblet cell hyperplasia lasting at least a year after complete viral clearance. During the acute response to virus, same-strain ICAM-1-null mice are protected from airway inflammation and hyperreactivity despite similar viral infection rates, but the chronic response proceeds despite ICAM-1 deficiency. Neither response is influenced by IFN-gamma deficiency, but the chronic response is at least partially prevented by glucocorticoid treatment. In contrast to viral infection, allergen challenge caused only short-term expression of asthma phenotypes. Thus, paramyxoviruses cause both acute airway inflammation/hyperreactivity and chronic airway remodeling/hyperreactivity phenotypes (the latter by a hit-and-run strategy, since viral effects persist after clearance). These two phenotypes can be segregated by their dependence on the ICAM-1 gene and so depend on distinct controls that appear critical for the development of lifelong airway diseases such as asthma.

Acute Disease↗
PubMed2002

Determinants of outcome for patients admitted to a long-term ventilator unit.

BACKGROUND: This prospective cohort study was done to identify determinants of successful weaning from mechanical ventilation among patients admitted to the 10-bed long-term ventilator unit (LTVU) of a teaching hospital. METHODS: Prospective patient surveillance and data collection were done on 472 patients admitted to the LTVU over a 4-year period (January 1996 to December 1999). RESULTS: Multiple logistic regression analysis showed that the absence of home mechanical ventilation at the time of hospital admission, absence of intensive care unit (ICU) readmission, and admission to the LTVU from a nonmedical service were independently associated with successful weaning. No statistical difference between hospital survivors and nonsurvivors was associated with length of stay in the LTVU and length of stay in the hospital. CONCLUSIONS: Patients admitted to an LTVU require prolonged hospitalizations and intensive resource utilization. These data suggest that improved methods for identifying patients who are unlikely to benefit from prolonged mechanical ventilation may assist physicians in their discussions with patients and family members as they consider various treatment options.

Aged↗
PubMed2001

Interferon-gamma-induced epithelial ICAM-1 expression and monocyte adhesion. Involvement of protein kinase C-dependent c-Src tyrosine kinase activation pathway.

Interferon-gamma (IFN-gamma) induced intercellular adhesion molecule-1 (ICAM-1) expression in human NCI-H292 epithelial cells, as shown by enzyme-linked immunosorbent assay and immunofluorescence staining. The enhanced ICAM-1 expression resulted in increased adhesion of U937 cells to NCI-H292 cells. Tyrosine kinase inhibitors (genistein or herbimycin), Src family inhibitor (PP2), or a phosphatidylinositol-phospholipase C inhibitor (U73122) attenuated the IFN-gamma-induced ICAM-1 expression. Protein kinase C (PKC) inhibitors (staurosporine or Ro 31-8220) also inhibited IFN-gamma-induced response. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a PKC activator, stimulated ICAM-1 expression; this effect was inhibited by tyrosine kinase or Src inhibitor. ICAM-1 promoter activity was enhanced by IFN-gamma and TPA in cells transfected with pIC339-Luc, containing the downstream NF-kappaB and gamma-activated site (GAS) sites, but not in cells transfected with GAS-deletion mutant, pIC135 (DeltaAP2). Electrophoretic gel mobility shift assay demonstrated that GAS-binding complexes in IFN-gamma-stimulated cells contained STAT1alpha. The IFN-gamma-induced ICAM-1 promoter activity was inhibited by tyrosine kinase inhibitors, a phosphatidylinositol-phospholipase C inhibitor, or PKC inhibitors, and the TPA-induced ICAM-1 promoter activity was also inhibited by tyrosine kinase inhibitors. Cotransfection with a PLC-gamma2 mutant inhibited IFN-gamma- but not TPA-induced ICAM-1 promoter activity. However, cotransfection with dominant negative mutants of PKCalpha or c-Src inhibited both IFN-gamma- and TPA-induced ICAM-1 promoter activity. The ICAM-1 promoter activity was stimulated by cotransfection with wild type PLC-gamma2, PKCalpha, c-Src, JAK1, or STAT1. An immunocomplex kinase assay showed that both IFN-gamma and TPA activated c-Src and Lyn activities and that these effects were inhibited by staurosporine and herbimycin. Thus, in NCI-H292 epithelial cells, IFN-gamma activates PLC-gamma2 via an upstream tyrosine kinase to induce activation of PKC-alpha and c-Src or Lyn, resulting in activation of STAT1alpha, and GAS in the ICAM-1 promoter, followed by initiation of ICAM-1 expression and monocyte adhesion.

Animals↗