Danforth A. Newton

Hemoglobin Is Expressed by Alveolar Epithelial Cells

Hemoglobin gene expression in non-erythroid cells has been previously reported in activated macrophages from adult mice and lens cells, and recent studies indicate that alveolar epithelial cells can be derived from hematopoietic stem cells. Our laboratory has now produced strong evidence that hemoglobin is expressed by alveolar type II (ATII) cells and Clara cells, the primary producers of pulmonary surfactant. ATII cells are also closely involved in innate immunity within the lung and are stem cells that differentiate into alveolar type I cells. Reverse transcriptase-PCR was used to measure the expression of transcripts from the α- and β-globin gene clusters in several human and rodent pulmonary epithelial cells. Surprisingly, the two major globin mRNAs characteristic of adult erythroid precursor cells were clearly expressed in human A549 and H441 cell lines, mouse MLE-15 cells, and primary ATII cells isolated from normal rat and mouse lungs. DNA sequencing verified that these PCR products were indeed the result of specific amplification of globin gene cDNAs. These alveolar epithelial cells also expressed the corresponding hemoglobin protein subunits as determined by Western blotting, and tandem mass spectrometry sequencing was used to verify the presence of both α- and β-globin polypeptides in rat primary ATII cells. The function of hemoglobin expression by cells of the pulmonary epithelium will be determined by future studies, but this novel finding could potentially have important implications for the physiology and pathology of the lung.

Surfactant protein C-deficient mice are susceptible to respiratory syncytial virus infection.

Patients with mutations in the pulmonary surfactant protein C (SP-C) gene develop interstitial lung disease and pulmonary exacerbations associated with viral infections including respiratory syncytial virus (RSV). Pulmonary infection with RSV caused more severe interstitial thickening, air space consolidation, and goblet cell hyperplasia in SP-C-deficient (Sftpc(-/-)) mice compared with SP-C replete mice. The RSV-induced pathology resolved more slowly in Sftpc(-/-) mice with lung inflammation persistent up to 30 days postinfection. Polymorphonuclear leukocyte and macrophage counts were increased in the bronchoalveolar lavage (BAL) fluid of Sftpc(-/-) mice. Viral titers and viral F and G protein mRNA were significantly increased in both Sftpc(-/-) and heterozygous Sftpc(+/-) mice compared with controls. Expression of Toll-like receptor 3 (TLR3) mRNA was increased in the lungs of Sftpc(-/-) mice relative to Sftpc(+/+) mice before and after RSV infection. Consistent with the increased TLR3 expression, BAL inflammatory cells were increased in the Sftpc(-/-) mice after exposure to a TLR3-specific ligand, poly(I:C). Preparations of purified SP-C and synthetic phospholipids blocked poly(I:C)-induced TLR3 signaling in vitro. SP-C deficiency increases the severity of RSV-induced pulmonary inflammation through regulation of TLR3 signaling.

Hypoxia Up-Regulates Expression of Hemoglobin in Alveolar Epithelial Cells

Alveolar epithelial cells are directly exposed to acute and chronic fluctuations in alveolar oxygen tension. Previously, we found that the oxygen-binding protein hemoglobin is expressed in alveolar Type II cells (ATII). Here, we report that ATII cells also express a number of highly specific transcription factors and other genes normally associated with hemoglobin biosynthesis in erythroid precursors. Because hypoxia-inducible factors (HIFs) were shown to play a role in hypoxia-induced changes in ATII homeostasis, we hypothesized that the hypoxia-induced increase in intracellular HIF exerts a concomitant effect on ATII hemoglobin expression. Treatment of cells from the ATII-like immortalized mouse lung epithelial cell line-15 (MLE-15) with hypoxia for 20 hours resulted in dramatic increases in cellular levels of HIF-2α protein and parallel significant increases in hemoglobin messenger RNA (mRNA) and protein expression, as compared with that of control cells cultured in normoxia. Significant increases in the mRNA of globin-associated transcription factors were also observed, and RNA interference (RNAi) experiments demonstrated that the expression of hemoglobin is at least partially dependent on the cellular levels of globin-associated transcription factor isoform 1 (GATA-1). Conversely, levels of prosurfactant proteins B and C significantly decreased in the same cells after exposure to hypoxia. The treatment of MLE-15 cells cultured in normoxia with prolyl 4-hydroxylase inhibitors, which mimic the effects of hypoxia, resulted in increases of hemoglobin and decreases of surfactant proteins. Taken together, these results suggest a relationship between hypoxia, HIFs, and the expression of hemoglobin, and imply that hemoglobin may be involved in the oxygen-sensing pathway in alveolar epithelial cells.

Cross-reactivity between HLA-A2-restricted FLU-M1:58–66 and HIV p17 GAG:77–85 epitopes in HIV-infected and uninfected individuals

BackgroundThe matrix protein of the influenza A virus and the matrix and capsid proteins of the human immunodeficiency virus (HIV) share striking structural similarities which may have evolutionary and biological significance. These similarities led us to hypothesize the existence of cross-reactivity between HLA-A2-restricted FLU-M1:58–66 and HIV-1 p17 GAG:77–85 epitopes.MethodsThe hypothesis that these two epitopes are cross-reactive was tested by determining the presence and extent of FLU/GAG immune cross-reactivity in lymphocytes from HIV-seropositive and seronegative HLA-A2+ donors by cytotoxicity assays and tetramer analyses. Moreover, the molecular basis for FLU/GAG cross-reactivity in HIV-seropositive and seronegative donors was studied by comparing lymphocyte-derived cDNA sequences corresponding to the TCR-β variable regions, in order to determine whether stimulation of lymphocytes with either peptide results in the expansion of identical T-cell clonotypes.ResultsHere, we report evidence of cross-reactivity between FLU-M1:58–66 and HIV-1 p17 GAG:77–85 epitopes following in vitro stimulation of PBMC derived from either HIV-seropositive or seronegative HLA-A2+ donors as determined by cytotoxicity assays, tetramer analyses, and molecular clonotyping.ConclusionThese results suggest that immunity to the matrix protein of the influenza virus may drive a specific immune response to an HLA-A2-restricted HIV gag epitope in HIV-infected and uninfected donors vaccinated against influenza.

Surfactant protein A and D in human sinus mucosa: a preliminary report.

Introduction: Surfactant-associated proteins (SPs) play a crucial role in the innate defense system and serve as the initial step in the immune response to inhaled pathogens. SP-A and SP-D expression and function are altered in a variety of inflammatory and infectious diseases of the lungs, such as asthma, allergies, and cystic fibrosis, but their presence and function in the sinonasal cavity has not been investigated. The objective of this study was to test our hypothesis that SP-A and SP-D are present in the human sinus. Materials and Methods: Sinus mucosal biopsies were performed in 8 patients undergoing endoscopic sinus surgery for chronic rhinosinusitis with nasal polyposis, pituitary tumors, and cerebrospinal fluid leak repairs. Expression of SP mRNA and protein by the sinus mucosa was detected by RT-PCR and immunoblot analysis, respectively. Results: Analyses of mucosal biopsies from these patients revealed the presence of SP-A and SP-D mRNA and protein in all specimens. Conclusion: SP-A and SP-D are expressed in both normal and diseased human sinus tissue. Understanding the role of SPs in diseased and healthy states may elucidate their possible roles in innate immunity in the upper airway and allow us to develop novel treatments for sinonasal pathologies.

Semiallogeneic cell hybrids as therapeutic vaccines for cancer.

The authors have engineered a cell line that can be used in human studies as a universal donor cell for the formation of semiallogeneic cell hybrids after fusion with patient-derived tumor cells. These hybrids can be irradiated and injected as a patient-tailored therapeutic vaccine in patients affected by virtually any type of cancer. A crucial step in this research effort has been the derivation of an allogeneic cell line (FO1-12) that expresses both a dominant selectable marker (neomycin resistance) and a recessive selectable marker (sensitivity to hypoxanthine, aminopterin, and thymidine), which allows easy selection of semiallogeneic cell hybrids derived from the fusion of FO1-12 cells with patient-derived tumor cells. Tumor-infiltrating lymphocytes derived from select patients with melanoma and exposed to semiallogeneic cell hybrids from the same patient were better able to specifically lyse autologous tumor cells. Furthermore, FO1-12 cells express carcinoembryonic antigen, which is ubiquitous in adenocarcinomas, and fusion of FO1-12 cells with various patient-derived adenocarcinoma cells showed that the hybrid cells also express carcinoembryonic antigen. Because of the results of these preclinical studies, the authors were given permission to use semiallogeneic cell hybrids for immunotherapy of patients with metastatic melanoma or metastatic adenocarcinoma who had not responded to standard treatment regimens. Treatment with semiallogeneic vaccines is associated with minimal or no toxicity and can induce a specific anti-tumor immune response.

CHARACTERIZATION OF ALVEOLAR EPITHELIAL CELLS CULTURED IN SEMIPERMEABLE HOLLOW FIBERS

Cell culture methods commonly used to represent alveolar epithelial cells in vivo have lacked airflow, a 3-dimensional air-liquid interface, and dynamic stretching characteristics of native lung tissue—physiological parameters critical for normal phenotypic gene expression and cellular function. Here the authors report the development of a selectively semipermeable hollow fiber culture system that more accurately mimics the in vivo microenvironment experienced by mammalian distal airway cells than in conventional or standard air-liquid interface culture. Murine lung epithelial cells (MLE-15) were cultured within semipermeable polyurethane hollow fibers and introduced to controlled airflow through the microfiber interior. Under these conditions, MLE-15 cells formed confluent monolayers, demonstrated a cuboidal morphology, formed tight junctions, and produced and secreted surfactant proteins. Numerous lamellar bodies and microvilli were present in MLE-15 cells grown in hollow fiber culture. Conversely, these alveolar type II cell characteristics were reduced in MLE-15 cells cultured in conventional 2D static culture systems. These data support the hypothesis that MLE-15 cells grown within our microfiber culture system in the presence of airflow maintain the phenotypic characteristics of type II cells to a higher degree than those grown in standard in vitro cell culture models. Application of our novel model system may prove advantageous for future studies of specific gene and protein expression involving alveolar epithelial or bronchiolar epithelial cells.

Semiallogeneic cancer vaccines formulated with granulocyte-macrophage colony-stimulating factor for patients with metastatic gastrointestinal adenocarcinomas: a pilot phase I study.

The authors report the results of a phase I clinical study using semiallogeneic cancer vaccines formulated with granulocyte-macrophage colony-stimulating factor (GM-CSF) to treat patients with metastatic adenocarcinomas of the gastrointestinal tract. A specially engineered cell line, FO1-12, was used to generate semiallogeneic hybrids by fusion with patient-derived tumor cells; the hybrids express HLA class I and II haplotypes derived from both parental cells. For treatment, the vaccine was mixed with GM-CSF, irradiated, and injected intradermally into patients at weekly or biweekly intervals. Vaccinations were associated with minimal or no toxicity and showed that semiallogeneic hybrids formulated with GM-CSF can induce a specific antitumor immune response in some patients, as measured by a delayed-type hypersensitivity response to autologous tumor cells. Because of the simplicity, feasibility, and flexibility of this immunotherapeutic approach, semiallogeneic hybrid vaccines have the potential to be used in the treatment of virtually any type of cancer.

Innate and adaptive mediators in cystic fibrosis and allergic fungal rhinosinusitis.

Background Surfactant-associated proteins (SP) A and D are both innate immunity mediators and produced in normal and diseased sinus mucosa. Cystic fibrosis (CF) is associated with Th1 adaptive inflammation whereas allergic fungal rhinosinusitis (AFRS) is associated with Th2 adaptive inflammation. The purpose of this study is to show and quantify the presence of SP A, SP D, tumor necrosis factor (TNF) alpha, (a Th1 marker), and eotaxin (a Th2 marker) in normal and diseased sinus mucosa. Methods Intraoperative sinus mucosal biopsy specimens from human volunteers were obtained during endoscopic sinus surgery for CF (n = 4), AFRS (n = 10), and normal controls (CTLs; n = 4). Specimens were evaluated for presence and quantity of SP A, SP D, and TNF-alpha using Western blot with semiquantitative immunoblot analysis. Eotaxin was quantified using ELISA immunoassay. Results were standardized and reported as picograms of mediator per microgram of total protein. Results SP A, SP D, and TNF-alpha levels in CF tissue extracts were 2–10 times higher than levels in AFRS tissue (with SP D and TNF-alpha reaching statistical significance) but CF tissue was not significantly higher than CTL tissue. SP A, SP D, and TNF-alpha were not significantly elevated in AFRS. Eotaxin showed elevated levels in CF and AFRS when compared with CTLs (p = 0.03 and 0.003, respectively). Conclusion SP D and TNF-alpha are significantly increased in CF compared with AFRS, suggesting activation of both innate immunity and Th1-mediated inflammation and potential correlation between SPs and downstream adaptive immune responses.

Semi-allogeneic cell hybrids stimulate HIV-1 envelope-specific cytotoxic T lymphocytes.

ObjectiveThe present study was designed to determine whether the HLA allogeneic T helper response stimulated by semi-allogeneic cell lines could be used as an in vitro model of immune-based therapy to stimulate HIV-specific cytotoxic T lymphocytes. Design and methodsSemi-allogeneic cell hybrids were obtained by the fusion of peripheral blood mononuclear cells from HIV-infected patients with the allogeneic β2-microglobulin-deficient FO1-12 melanoma cell line. These hybrids were used as antigen presenting cells for HIV envelope peptide (env)-specific cytotoxic assays. ResultsThe hybrid cell lines express HLA class I and II antigens from both parental cells, as well as the CD86 costimulatory molecule. HIV-specific cytotoxic T lymphocyte activity was obtained when patients’ peripheral blood mononuclear cells were costimulated with env peptides plus semi-allogeneic hybrids, in contrast with stimulation with either env or hybrid cells alone. Thus, the semi-allogeneic hybrids enhanced HIV-specific killing of target cells. ConclusionsIrradiated, semi-allogeneic cell hybrids engineered for individual AIDS patients provide efficient and simultaneous co-recognition of HLA allogeneic determinants and viral antigenic determinants presented by self-HLA molecules on the same antigen presenting cells and results in the generation of enhanced HIV-specific cytotoxic T lymphocyte activity.