HL57125 - Andrew H. Limper - Mayo Foundation, Rochester, MN
Pneumocystis carinii is an opportunistic organism which causes severe pneumonia in immuno-compromised hosts, especially those with AIDS. Recent investigations have advanced our under-standing of host-organism interactions during P. carinii pneumonia. Adhesive proteins present in the alveolar spaces, including surfactant components, bind to P. carinii and modulate interactions with alveolar macrophages. P. carinii pneumonia is characterized by protein-rich alveolar exudates laden with organisms. The group recently reported that these exudates are particularly rich in surfactant protein D (SP-D), a soluble component of the alveolar lining material. SP-D is a group III C-type lectin implicated in host defense against infectious agents. They found that S P-D accumulates in the lung during P. carinii pneumonia and that SP-D binds specifically to the highly glycosylated major surface antigen complex of P. carinii termed gpA. This lead them to hypothesize that SP-D, interacts specifically with P. carinii through saccharidemediated mechanisms. They also postulate that the binding of SP-D to P. carinii, potentiates aggregation of the organism, alters macrophage uptake and degradation of P. carinii, and modulates macrophage release of tumor necrosis factor-alpha (TNF-alpha) and eicosanoids. Interactions between purified SP-D and P. carinii will be further characterized, e.g. determining the precise sugar specificities, pH optimum and divalent cation requirements for binding. The site on SP-D interacting with P. carinii will be mapped and binding of active full-length recombinant SP-D evaluated. Other experiments will address the significance of SP-D binding to P. carinii by determining the role of SP-D in mediating P. carinii aggregation and in modulating uptake and degradation of the organism by macrophages. The role of SP-D in macrophage release of inflammatory mediators including TNF-alpha and eicosanoids will be evaluated. Inhibition of SP-D's interactions with P. carinii will be studied using anti-SP-D Fab antibodies or maltosyl-BSA to see how this affects severity of infection and established P. carinii pneumonia a CD4 lymphocyte-deficient murine model that resembles AIDS.
The grant is being supported from 1996 to 1999.
R29 HL57960 - Marcella Billstrom - National Jewish Med. and Res. Ctr, Denver, Colorado
This investigator will study Infection of the lung by Human Cytomegalovirus (HCMV) which leads to inflammatory pneumonitis of great clinical significance. The site and mechanism by which the inflammatory response is regulated remain unclear. During infection of the endothelium, HCMV-induced mechanisms stimulate the expression of the chemokine RANTES. Furthermore, HCMV encodes a G-protein coupled receptor, US28, that binds and signals through CC chemokines and is responsible for depleting extracellular concentrations of the chemokine RANTES during endothelial infection. She postulates that HCMV modulates local inflammatory responses in part by encoding a chemokine receptor US28 that regulates the local concentration of RANTES through receptor internalization, and blocks apoptotic mechanisms during RANTES stimulation of infected cells. The goal of the project is to determine whether signaling pathways leading to inhibition of apoptosis (Raf, ERK activation) are activated or signaling pathways resulting in apoptosis (MEKK, JNK, p38 activation) are inhibited during RANTES stimulation of US28. Further understanding of the role of US28 during infection will provide information on the mechanisms of HCMV-induced modification of local inflammatory responses that lead to persistent infection.
This grant is being supported from 1997 to 2002
Title: Macrophage Recruitment/Activation in Lung Defense
R01 HL51082 - Galen B. Toews - University of MI Medical Center, Ann Arbor, MI
Cryptococcus neoformans is an ubiquitous yeast which is the most common cause of fatal fungal infection in patients with AIDS. The respiratory tract is the portal of entry for this opportunistic infection. Pulmonary clearance is dependent on the ability of the host to mount a protective T cell-mediated inflammatory response in the lung. The recruitment and activation of monocytes is a hallmark of an effective pulmonary response to C. neoformans. Macrophages direct the outcome of the infectious challenge at two fundamental levels: 1) macrophages are the resident, initial cellular defense against C. neoformans; 2) macrophages elaborate cytokines which control the development and expression of specific T cell immunity orchestrating both the level and types of T cell cytokines produced in this response. The proposed studies will focus on the signals required to activate macrophages and the cytokines "activated" macrophages produce to drive T cells to either a Tc1/Th1 or a Tc2/Th2 cytokine profile. Hypothesis: CD8 T cells generated in lung and hilar nodes during pulmonary C. neoformans infections produce chemokines and IFN-gamma early in the infection; these cytokines are crucial for recruiting and priming macrophages for IL-12 production and the development of protective Tc1 and Th1 responses. Secondly, protective CD8 T cells, which produce cytokines that recruit and activate macrophages, can be generated in CD4-depleted animals. The proposed experiments will use specific monoclonal antibodies to block cytokines and deplete cells, "knock out" mice that are homozygous -/- or the disruption of key genes and the transfer of defined cells into immunodeficient scid mice to define the essential requisites for effective in vivo antimicrobial immunity to C. neoformans. In aggregate, the in vivo experiments will suggest novel approaches to macrophage recruitment and activation during states of prolonged CD4 depletion.
This grant is being supported from 1997 to 1998 (previously supported as non-AIDS research from 1993 to 1997).
R01 HL50795 - Jeffrey M. Drazen - Brigham and Women's Hospital, Boston, MA
Acquired Immunodeficiency Syndrome (AIDS) is no longer restricted to gay white men. Women, especially women of color, represent the most rapidly-growing segment of persons infected with HIV (human immunodeficiency virus). Despite the increasing frequency of HIV infection in women, virtually all the information available regarding the natural history of HIV infection and its effects on the lung is derived from studies of infected men. Recent reports suggest that important gender differences exist in the type and frequency of complications, particularly in regard to respiratory disease. In both genders in the general population, cigarette smoking represents the major preventable cause of respiratory morbidity and mortality, accelerating loss of lung function and predisposing to bacterial and other infections. In HIV-infected individuals, preliminary reports (again mainly in men) suggest that cigarette smoking may predispose to bacterial pneumonia and may worsen the pulmonary dysfunction which occurs after PCP. Based on these data, the investigators hypothesize that cigarette smoking among HIV-infected women alters the spectrum, frequency, and severity of respiratory complications (both non-infectious and infectious) of HIV infection. Specifically, they surmise that in HIV-seropositive women, cigarette smoking increases airway hyperresponsiveness, accelerates the loss of lung function, and predisposes to the development of obstructive lung disease. Furthermore, it is conjectured that cigarette smoking affects the type and extent of acute and chronic respiratory infections that these women experience. To test this hypothesis, the group will assess respiratory health by lung function testing, by questionnaire and by surveillance for infectious complications over the course of a 3 year observation period in a cohort of HIV-seropositive women -- representatively diverse in terms of race/ethnicity, HIV risk factors, socioeconomic status, and smoking exposure. For both non-infectious and infectious outcomes multiple regression analysis will be used to discern the relative importance of cigarette smoking as an independent risk for loss of lung function and infectious complications.
This grant is being supported from 1993 to 1998.
HL54972 - Shawn Skerrett - University of Washington, Seattle, WA
How intracellular pathogens such as Legionella pneumophila are eliminated from the lung is unknown. The mechanisms underlying parasitism of alveolar macrophages, the interactions of cytokines mediating the immunoregulatory and effector cell functions of alveolar macrophages, and relative contributions of macrophage activation and cytotoxic responses to the resolution of intracellular infection in the lung are unknown. The growing population of immunocompromised individuals susceptible to opportunistic infection underscores the importance of developing new strategies for the prevention and treatment of intracellular infections. The objective of this proposal is to define molecular and cellular elements of the protective host responses to intracellular infections of the lung and to identify potential approaches to the augmentation of host resistance by combining in vitro work with human alveolar macrophages and in vivo studies in mice with specific cytokine deficiencies.
This grant is being supported from 1996 to 2001.
The investigators reported that IL-10, but not IL-4 or TGF-ß increase replication of Legionella pneumophilia in human macrophages. These cytokines reverse the protective effect of IFN-gamma. Blocking release of endogenous TNF-alpha also promotes bacterial replication, however, exogenous TNF-alpha does not appear to protect against the effects of IL-10. Monocytes seem to be much more sensitive to the effects of IL-10 than alveolar macrophages.
HL56026 - Scott Pottratz - Indiana University-Purdue University, Indianapolis, IN Pneumocystis carinii (PC) pneumonia is a frequent cause of morbidity and mortality in immuno-suppressed individuals, especially in those with HIV infection. Attachment of PC organisms to the alveolar epithelium with subsequent damage to the epithelial cell barrier is a pathologic hallmark of PC pneumonia. This study will attempt: 1) to determine whether PC and its major surface glycoprotein (gp120) induce IL-6 secretion and changes in IL-6 mRNA expression in A549 cells and primary cultures of rat alveolar epithelial cells; 2) to determine whether the effect of PC on alveolar epithelial cell IL-6 expression requires attachment of PC organisms to the alveolar epithelial cells; 3) to determine the effect of IL-6 on PC attachment to alveolar epithelial cells; 4) to determine the effect of IL-6 on production of Fn and Vn and expression of cell surface FN- and Vn- binding integrins (alpha5, alpha-v, beta1, beta5 and beta6) on alveolar epithelial cells.
This grant is being supported from 1996 to 2001.
P. carinii organisms were found to induce production of IL-6 by an alveolar epithelial cell line (A549 cells). The quantity of IL-6 produced is dependent on the number of P. carinii organisms attached to the alveolar cells. It is likely that increased IL-6 production benefits the organisms because IL-6 induces production of the extracellular matrix protein fibronectin (Fn), which appears to aid in the attachment of P. carinii to the lung epithelial cells.
HL56309 - Jeffrey Curtis - University of Michigan, Ann Arbor, MI
This group will examine the lung's local immune responses to inhaled antigens. To study pulmonary immunoregulation, this group developed an experimental model system in which antigen-primed C57BL/6 mice are intratracheally challenged with the T cell-dependent antigen sheep red blood cells, inducing a response which is vigorous but, importantly, self-terminating. The specific aimes are: 1) determine whether pulmo-nary lymphocyte apoptosis is Fas-dependent; 2) determine whether pulmonary lymphocyte apoptosis is blocked by over-expression of anti-apoptosis genes of the Bcl-2 family; 3) determine whether pulmonary T cells are cell-cycle arrested; 4) determine which pulmonary APC trigger or prevent lymphocyte apoptosis; 5) determine which pulmonary lymphocyte subsets are committed to apoptosis.
This grant is being supported from 1996 to 2001.
Preliminary findings show that apoptosis contributes to lung lymphocyte elimination in the mouse model response to intratracheal particulate antigens. The investigators are now looking at how the response to repeated challenges is downregulated. Understanding how activated lymphocytes are removed from the lungs after exposure to infectious agents or allergens may lead to novel therapies.
HL55549 - David Riches - National Jewish Ctr for Immnlgy/Resp Med, Denver, CO
Tumor necrosis factor has been implicated in the pathobiology of lung disease in AIDS. The specific aims of this study are: 1) to purify and clone the phosphoproteins, pp95 and pp120, that are constitutively associated with the intracellular domain of CD120a (p55); 2) to investigate the functions of pp95 and pp120 and to define the region(s) within the ID of CD120a (p55) that interact with pp95 and pp120; 3) to determine the upstream kinase(s) and signaling components responsible for activating p42mapk/erk2.
This grant is being supported from 1996 to 2000.
TNF-à is recognized by cell surface receptors and subsequently kinases are activated that mediate a variety of intracellular signaling events. The investigator reports that TNF-à preferentially stimulates one of the kinases, MEK1. Understanding how kinase activation occurs may someday help to control inflammatory responses, fibrotic responses and HIV replication.
HL57566 - Susan Sullivan - One Cell Systems, Inc., Cambridge, MA
The control of multidrug-resistant tuberculosis has been hampered by the lack of rapid methods for antimicrobial susceptibility testing. This SBIR program is designed to provide a novel approach to rapid antibiotic susceptibility testing, based on One Cell Systems proprietary gel microdrp encapsulation technology. The research is designed to increase the detection sensitivity to 1 percent resistance and evaluate this technology using clinical samples.
This grant is being supported from 1993 to 1998.
This is a newly funded grant. Results are preliminary and have not yet been published.
HL48287 - Jeffrey Warren - University of Michigan, Ann Arbor, MI
The spectrum of granulomatous lung disease is broad, encompassing diseases caused by readily identifiable microbial agents commonly seen in HIV infection (tuberculosis, mycobacterium avium intracellularae, histoplasmosis, schistosomiasis). Central to granuloma formation is the coordinated recruitment of mononuclear phagocytes, and in some types of lesions. In this study, the role of neutrophils and reactive oxygen intermediates in the induction of beta-chemokines will be studied in vivo and in vitro. Granuloma development and beta-chemokine expression will be examined in neutrophil-sufficient, neutrophil-depleted, and specific antioxidant-treated animals. Finally, biochemical and molecular mechanisms of neutrophil reactive oxygen intermediate-induced beta-chemokine expression will be systematically examined in isolated human endothelial cells, alveolar type II epithelial cells, and fibroblasts.
This grant is being supported from 1997 to 2001.
This is a newly funded grant. Results are preliminary and have not yet been published.
HL49610 - Constantine Haidaris University of Rochester, Rochester, NY
Pneumonia caused by the opportunistic pathogen Pneumocystis carinii is a primary cause of mortality in patients with acquired immunodeficiency syndrome and in other immunocompromised hosts. The goal of the proposed study is to identify antigens of P. carinii that are involved in acquired resistance to infection. Patients or infected animals that have recovered from P. carinii pneumonia demonstrate an immune response to an abundant, immunodominant surface glycoprotein of P. carinii, which in the ferret model of PCP has an Mr of 120 kDa. This and other data indicate that the surface glycoprotein is important in the host-P. carinii interaction. The immediate focus of this proposal is to perform a molecular biological analysis of ferret P. carinii gp 120.
This grant is being supported from 1992 to 1999.
This is a newly funded grant. Results are preliminary and have not yet been published.
RO1 HL50499 - Ronald Daniele - University of Pennsylvania, Philadelphia, PA
Accumulating evidence suggests that defects in alveolar macrophage function may contribute to the observed pulmonary opportunistic infections in HIV-1-infected individuals. These investigators will examine the role of fibronectin receptors in controlling the adherence and motile properties of alveolar macrophages. After identifying fibronectin receptors (integrins) on lung macrophages that bind to fibronectin, the investigators plan to use a mathematical model to guide them in examining the role of receptor-ligand (fibronectin) interactions in regulating the adhesive strength of alveolar macrophages and the motile behavior. Finally, the investigators will employ video microscopy and image analysis to test their hypotheses regarding relationships between cell speed and fibronectin density. Understanding these interactions could have broad applicability to other receptor-ligand interactions and might provide better understanding of the interaction between cell surface receptors and ligands bound to structures in the extracellular matrix.
This grant is being supported from 1994 to 1999.
This is a newly funded grant. Results are reliminary and have not yet been published.
RO1 HL40871 - Mark Wewers - OH State Univ. Research Foundation, Columbus, OH
Individuals with HIV-1 infection experience frequent bacterial pulmonary infections, even early in the course of their disease. This investigator is studying the molecular events involved in the processing and secretion of interleukin 1 beta from human monocytes and alveolar macrophages. Interleukin 1ß has an important role in sepsis-induced shock and pulmonary tissue injury. Interleukin 1 can promote and maintain inflammation via its potent effects on many tissues. For example, IL-1 induces vascular endothelium to display integrins, triggers neutrophils to activation and migration, signals mesenchymal cells to proliferate, and initiates a secondary cascade of cytokines such as IL-6 and IL-8. Thus IL-1 regulates many subsequent inflammatory events.
This grant is being supported from 1989 to 1999.
The investigators have found that C-reactive protein, whose levels increase during infection, inhibits the production of IL-1 by alveolar macrophages. They have determined that microtubules in macrophages are involved in the production of the precursor to IL-1 by macrophages in response to bacterial endotoxin, but are not likely to playa role in the regulation of secretion of IL-1. The investigators have also determined that monocytes, in response to IL-1, release an antagonist to the IL-1 receptor, but that mature macrophages did not increase production of the antagonist above constitutive levels, suggesting that the lack of response of macrophages is due to basal synthesis of the antagonist blockage of the IL-1 receptor.
P01 HL43510 - Jerome Groopman - New England Deaconess Hospital, Boston, MA
This multidisciplinary project is focused on a better understanding of the impairment in pulmonary host defense in HIV-associated infections. The information gained from basic studies will be used to develop novel therapies aimed at restoring host defense. Functional abnormalities of host defense in the lung related to important opportunistic pathogens (P. carinii, Mycobacterium tuberculosis, and cytomegalovirus) will be investigated. Small animal models will be used to explore methods of delivery of cytokines and soluble receptors to the lung.
This grant is being supported from 1989 to 1999.
Studies with P. carinii have demonstrated that the mannose receptor on human macrophages function directly in recognition of P. carinii organisms. It appears that expression of the mannose receptor, a first-line host defense receptor, is impaired in HIV-infected persons. Results from investigation of the interaction of Mycobacterium avium with macrophages from HIV-infected individuals showed a blunted cytokine response; survival of human macrophages infected with M. avium correlated with the synthesis of tumor necrosis factor alpha and interleukin-6. Work on the regulation of HIV transcription and the nature of viral tropism in the monocyte/macrophage revealed that the long terminal repeat was not a major determinant of cellular tropism for HIV-1. Further studies suggest that HIV infection, per se, does not marked alter cytokine expression by monocytes/macrophages but, rather, is capable of modulating the cell's response to subsequent stimuli such as lipopolysaccharide.
R01 HL51509 - Frank Martiniuk - NY University Medical Center, New York, NY
This investigator will investigate the genetic mechanisms of isoniazid (INH) and rifampicin resistance in Mycobacterium tuberculosis (Mtb). These drugs are the major therapeutic agents for TB and resistance to them reduces the chance of clinical cure of TB from 100 percent to 50 percent.
Dr.Martiniuk will attempt to isolate and characterize the gene(s) responsible for INH-resistant Mtb. The target of INH in Mtb is unknown, but metabolic pathways have been suggested the include the mycolic acid and NAD recycling pathways. Recently, a deletion of the catalase/peroxidase gene has been shown to be responsible for 15-25 percent of INH-resistant strains of TB. The investigators propose to identify the other genes involved in INH resistance and: (1) to clone and identify the DNA segments involved in INH resistance of Mtb by generating libraries from both INH-resistant and -sensitive strains and identifying clones that result in transformation of a resistant strain to sensitive and vice versa; (2) to enumerate the mechanisms of resistance that presently exist, by utilizing various strains of both as donors and recipients; and (3) to identify mechanisms in the Mtb beta subunit of RNA polymerase that confer resistance to rifampicin.
This grant is being funded from 1994 to 1998.
The gene for the beta subunit of RNA polymerase from rifampicin resistant Mtb has been isolated. The group has obtained about 2,000 clinical isolates and has developed a modified a DNA fingerprinting' method to subtype individual bacteria and clones.
R01 HL51494 - William Rom - NY University Medical Center, New York, NY
Mycobacterium tuberculosis infection is epidemic in New York City among HIV-infected individuals, the homeless and intravenous drug users. Because the pathogenesis of tuberculosis (TB) is poorly understood, this investigator will study the role of cytokines/adhesion molecules in the pathophysiology of the lung. The study will include 100 patients with active TB and 100 age-matched controls stratified by HIV infection. Bronchoalveolar lavage of sites of radiographically determined disease will be performed and cytokines will be compared to uninvolved pulmonary sites and peripheral blood mononuclear cells. Tissue and BAL cytospins will be examined to evaluate cellular distribution of cytokines/adhesion molecules through use of immunohistochemistry and in situ hybridization techniques. A transgenic mouse model deficient in expression of the IFN-gamma receptor and infected with BCG, a less pathogenic mycobacterium than MTB, will be used to study the resistant cytokine/adhesion molecule responses. These studies will provide an integrated model of how cytokines and adhesion molecules direct the granulomatous response to mycobacterial infection and will provide the rationale for modulating cytokines in new therapies to accelerate phagocytosis and killing of MTB. These studies will be critically important to the health of minorities, the ones most severely afflicted with the more resistant strains of TB.
This grant is being supported from 1994 to 1998.
This is a newly funded grant. Results are preliminary and have not yet been published.
R01 HL51474 - Michael Weiden NY University Medical Center, New York, NY
The sudden emergence of multi-drug resistant tuberculosis (MDR-TB), especially in epidemic form, has created a major stumbling block to controlling the current epidemic of TB in this country. Understanding the genetics of MDR-TB will prove valuable in studying the epidemiology of MDR-TB and contribute to generating effective public health policy for controlling this devastating infection. The investigators will utilize the high molecular weight DNA separation technique of pulsed-field gel electrophoresis to develop a new restriction fragment length polymorphism (RFLP) system to identify drug-resistant TB strains. They hope to define close genetic linkage of drug resistance with RFLP patterns.
This grant is being supported from 1994 to 1998.
This group reports that Mtb co-infection enhances HIV-1 levels in plasma and involved lung. Mtb increases HIV-1 production in acutely infected macrophage like cell lines. Production of lymphocytic tropic strains increases whereas macrophage tropic strains are suppressed. The investigators speculate that Mtb infection may hasten the tropism conversion that has been observed to occur in the late stages of HIV-1 infection. Other preliminary findings suggest that NF-IL-6 downregulates HIV-1 promoter activity in vitro and HIV-1 replication in vivo.
R01 HL51517 - Michael Marmor - NY University Medical Center, New York, NY
The objectives of this application are: (1) the description of the TB epidemic in a black inner-city population, (2) the determination of factors contributing to compliance or noncompliance with prophylaxis and treatment, and (3) the determination of the impact of co-infection with HIV upon the expression of TB.
This grant is being supported from 1994 to 1998.
K08 HL02703 - Homer Twigg - Indiana University, Indianapolis, IN
Dr. Twigg is investigating the hypothesis that lymphocytic alveolitis in HIV-infected patients results from active proliferation of DC8 cytotoxic T lymphocytes in response to HIV infection and that these cells may further contribute to impairment of immune function by mediating depletion of CD4-positive T cells and alveolar macrophages.
This grant is being supported from 1993 to 1997.
The investigators found that lung lymphocytes from HIV-infected patients are activated cells capable of undergoing spontaneous as well as cytokine-induced lymphoproliferation within lung airspaces. The lung lymphocytes from HIV-infected subjects were found to secrete significantly more IL-2 and IFN-gamma and to stimulate inflammatory responses. IFN-gamma can induce lymphocytes to differentiate into killer cells.
HIV-infected subjects who are nonsmokers were observed to have more lymphocytes in their bronchoalveolar lavage fluid than HIV-infected smokers. Subsequent studies indicated that not only did the nonsmokers have more alveolitis, but this affliction was associated with better alveolar macrophage function per mitogen assays. The alveolar macrophages from nonsmokers secreted greater amounts of cytokines IL-2 and IL-6, important in T cell proliferation, than did alveolar macrophages from smokers.
R01 HL43628 - David Volsky - St. Luke's-Roosevelt Inst. for Health Sci., NY, NY
This study will investigate the relationship of alveolar macrophages to pulmonary disease in HIV-1 infection. These investigators are studying: (1) the frequency of HIV-1 infection in alveolar macrophage from AIDS patients, (2) the entry and expression of HIV-1 in alveolar macrophage in vitro, (3) the impact of HIV-1 infection on alveolar macrophage function, (4) effects of modulation of alveolar macrophage activity on HIV-1 expression and alveolar macrophage function, and (5) transmission of HIV-1 from alveolar macrophage to other cells in the course of immune response.
This grant is being supported from 1989 to 1998.
HIV-1 infection proceeds differently in its primary target cells, non-transformed T lymphocytes and macrophages, than it does in their transformed counterparts. The HIV-1 vif gene appears to be a major determinant of success of infection of primary T cells, as well as a factor in determining the progress of infection of certain T cell and monocyte lines. The vif gene appears to act late in viral infection to influence the infectivity of progeny virus, specifically to modify progeny virus for optimal reverse transcription. Depending upon the host and target cell, virions synthesized in the absence of vif fail to synthesize complete viral DNA, although their ability to enter cells appears unimpaired. Thus, vif constitutes an attractive target for intervention during the course of HIV-1 infection in humans.
R01 HL44281 - Veena Antony - Indiana University, Indianapolis, IN
The investigator is examining the mechanism of action of inhaled pentamidine.
This grant is being supported from 1990 to 1997.
The group has developed a rat model to study inhalation of pentamidine and has found evidence suggesting that pentamidine decreases the release of oxidants by macrophages in both normal and immunosuppressed rats. This was found to occur in dose-dependent fashion. These in vitro experiments clearly demonstrate that the types of oxidant released by macrophages do injure P. Carinii.
Evidence has also been found that pentamidine causes increases in intracellular calcium. Studies are now being pursued to compare the mechanism of action of pentamidine to, hexamidine a chemically similar agent that is not toxic for P. Carinii. The differences between the two may provide additional information on how pentamidine kills the organism. In vitro studies showed that neither of the drugs appear to injure alveolar macrophages.
R01 HL44846 - Hardy Kornfeld, Boston University, Boston, MA
This group is studying the mechanism of HIV infection of alveolar macrophages and related phagocytic cells, and determining how this affects their capacity to phagocytose and inhibit and kill Cryptococcus neoformans, Mycobacterium avium-intracellular and Mycobacterium tuberculosis.
This grant is being supported from 1990 to 2000.
The group found that, in vitro, alveolar macrophages from HIV-positive individuals with CD4+ T cell counts greater than 200/nm3 inhibit C.neoformans to the same extent as alveolar macrophages from normal controls. Further studies show that in cultures of lung macrophages obtained from helathy, non-smoking volunteers, addition of IFN-gamma decreases the ability of these lung cells to supress the growth of C.neoformans. The investigators are examining the extent of infection of bronchoalveolar cells at various stages of HIV disaease. They are also investigatiung the effects of HIV-1 infection on macrophage function.
They found that as HIV-1 disease progresses the ability of the lung cells to limit growth of fungi diminishes. Lung cells obtained from HIV-infected and HIV-seronegative cigarette smokers also demonstrate impaired uptake and fungistasis of C.neoformans. Thus, smoking predisposes to cryptococosis. The mechanisms whereby HIV infection and smoking reduce fungistais need to be determined.
Discoveries about granulomatous inflammatory reactions typical of the response of the lung to infection with Mtb have also resulted from this grant. Although Mtb are engulfed by lung macrophages, these mycobacteria often escape destruction by the alveolar macrophages' bacterial killing mechanisms. To learn more about lung defenses against these still viable Mtb, host cell genes involved in tuberculosis pathology were screened to identify genes induced by mycobacterial infection. One of these is the gene for a chemoattractant protein, osteopontin, (also called early T lymphocyte activation protein 1, or Eta-1) which is stimulated when alveolar macrophages are infected with Mtb. Macrophages, lymphocytes and the extracellular matrix of pathologic tissue from tuberculosis patients contain osteopontin. It is now thought to be a key factor in initiating the granulomatous response, which if successful, walls off infected macrophages to prevent the spread of Mtb. Increased osteopontin gene expression has also been found in the lung tissue of patients with Silicosis, which like tuberculosis is a disease characterized by granuloma formation in the lungs. Osteopontin promotes macrophage migration and adhesion and may also attract lymphocytes and monocytes from the bloodstream to the site of infection and facilitate binding of cells to extracellular matrix, via fibronectin. Understanding more about the molecular basis of granuloma formation may eventually lead to new therapeutic strategies for treating tuberculosis. The TB studies were supported by (Kornfeld HL44846, and a non-AIDS grant, Center HL46563.)
R01 HL43524 - William Martin - Indiana University, Indianapolis, IN
These investigators are studying the mechanism(s) of attachment of P. carinii to target lung cells and whether P. carinii adversely affects lung cell function.
This grant is being supported from 1989 to 2000.
These investigators established that fibronectin has een found to be an important mediator for P. carinii attachment to alveolar macrophages. They also found that interferon alpha-activated alveolar macrophages kill P. carinii via induction of reactive nitrogen intermediates.
Since surfactant abnormalities may contribute to impairment of gas exchange in Pneumocystis carinii pneumonia (PCP), further studies were done to see if functionally abnormal surfactant present in PCP accounts, in part, for the impairment of gas exchange. These rat studies revealed that rats with PCP were deficient in an important component of surfactant, phosphatidylglycerol, as compared to control rats. However, administration of exogenous phosphatidylglycerol to the lung washings restored surface activity to normal. These findings suggest that surfactant replacement might help correct the impairment of gas exchange seen in PCP.
R01 HL49730 - James Gadek - Ohio State University, Columbus, OH
The specific aims of this proposal are to test the hypothesis that there is a set of specific functional abnormalities of the lung associated with HIV infection that: (1) resemble an accelerated form of emphysema, but are fundamentally different with respect to gas exchange and mechanics of breathing, compared to other forms of "classic" emphysema; and (2) are not associated with the incidence of opportunistic infection but, rather, the severity and/or chronicity of HIV infection.
This grant is being supported from 1993 to 1998.
To date, 85 of 147 HIV-infected patients (mean age = 34.7 years; mean CD4 count = 388), who had not developed opportunistic pneumonia, have been evaluated. Diffusion capacity (DLCO) was impaired in 44 percent of those studied who had values one standard deviation below the mean predicted values. Thirteen percent had DLCO values that were two standard deviations below the mean. These findings did not correlate with either smoking history or injection drug use and suggest significant changes took place in the pulmonary vascular bed.