Bindu Raju

Mycobacterium tuberculosis-Induced CXCR4 and Chemokine Expression Leads to Preferential X4 HIV-1 Replication in Human Macrophages

Opportunistic infections such as pulmonary tuberculosis (TB) increase local HIV-1 replication and mutation. As AIDS progresses, alteration of the HIV-1 gp120 V3 sequence is associated with a shift in viral coreceptor use from CCR5 (CD195) to CXCR4 (CD184). To better understand the effect of HIV/TB coinfection, we screened transcripts from bronchoalveolar lavage cells with high density cDNA arrays and found that CXCR4 mRNA is increased in patients with TB. Surprisingly, CXCR4 was predominately expressed on alveolar macrophages (AM). Mycobacterium tuberculosis infection of macrophages in vitro increased CXCR4 surface expression, whereas amelioration of disease reduced CXCR4 expression in vivo. Bronchoalveolar lavage fluid from TB patients had elevated levels of CCL4 (macrophage inflammatory protein-1β), CCL5 (RANTES), and CX3CL1 (fractalkine), but not CXCL12 (stromal-derived factor-1α). We found that M. tuberculosis infection of macrophages in vitro increased viral entry and RT of CXCR4, using HIV-1, but not of CCR5, using HIV-1. Lastly, HIV-1 derived from the lung contains CD14, suggesting that they were produced in AM. Our results demonstrate that TB produces a permissive environment for replication of CXCR4-using virus by increasing CXCR4 expression in AM and for suppression of CCR5-using HIV-1 by increasing CC chemokine expression. These changes explain in part why TB accelerates the course of AIDS. CXCR4 inhibitors are a rational therapeutic approach in HIV/TB coinfection.

Recombinant Gamma Interferon Stimulates Signal Transduction and Gene Expression in Alveolar Macrophages In Vitro and in Tuberculosis Patients

ABSTRACT Tuberculosis is the seventh leading cause of morbidity and mortality in the world, with eight million cases per year. Animal and human studies demonstrate an enrichment of CD4 cells at sites of disease, with a more favorable clinical course when there is a Th1 response with the presence of gamma interferon (IFN-γ). We previously treated patients who had multidrug-resistant tuberculosis with recombinant IFN-γ (rIFN-γ) in aerosol form and were able to convert smear-positive cases to smear negative with 12 treatments over 1 month. We hypothesized that rIFN-γ would induce signal transducer and activator of transcription (STAT) and interferon regulatory factor (IRF) binding activity in alveolar macrophages (AM). AM treated in vitro showed clear upregulation of STAT-1 and IRF-1 by rIFN-γ. STAT-1 was not activated and IRF-1 was only weakly induced after 1 day of infection by Mycobacterium tuberculosis TN913. In bronchoalveolar lavage (BAL) cells obtained from 10 of 10 tuberculosis patients 10 ± 2 days post-antituberculosis treatment, there was no detectable STAT-1 or IRF-1 DNA-binding activity. After 4 weeks of treatment with rIFN-γ aerosol in addition to the antituberculosis drugs, 10 of 10 patients had increased STAT-1, IRF-1, and/or IRF-9 DNA-binding activity in BAL cells from lung segments shown radiographically to be involved and in those shown to be uninvolved. Symptoms and chest radiographs improved, and amounts of macrophage inflammatory cytokines and human immunodeficiency virus type 1 (HIV-1) viral loads (in five of five HIV-1-coinfected patients) declined in the second BAL specimens. rIFN-γ aerosol induces signal transduction and gene expression in BAL cells and should be evaluated for efficacy in a randomized, controlled clinical trial.

Surfactant Protein A Modulates the Inflammatory Response in Macrophages during Tuberculosis

ABSTRACT Tuberculosis leads to immune activation and increased human immunodeficiency virus type 1 (HIV-1) replication in the lung. However, in vitro models of mycobacterial infection of human macrophages do not fully reproduce these in vivo observations, suggesting that there are additional host factors. Surfactant protein A (SP-A) is an important mediator of innate immunity in the lung. SP-A levels were assayed in the human lung by using bronchoalveolar lavage (BAL). There was a threefold reduction in SP-A levels during tuberculosis only in the radiographically involved lung segments, and the levels returned to normal after 1 month of treatment. The SP-A levels were inversely correlated with the percentage of neutrophils in BAL fluid, suggesting that low SP-A levels were associated with increased inflammation in the lung. Differentiated THP-1 macrophages were used to test the effect of decreasing SP-A levels on immune function. In the absence of infection with Mycobacterium tuberculosis, SP-A at doses ranging from 5 to 0.01 μg/ml inhibited both interleukin-6 (IL-6) production and HIV-1 long terminal repeat (LTR) activity. In macrophages infected with M. tuberculosis, SP-A augmented both IL-6 production and HIV-1 LTR activity. To better understand the effect of SP-A, we measured expression of CAAT/enhancer binding protein beta (C/EBPβ), a transcription factor central to the regulation of IL-6 and the HIV-1 LTR. In macrophages infected with M. tuberculosis, SP-A reduced expression of a dominant negative isoform of C/EBPβ. These data suggest that SP-A has pleiotropic effects even at the low concentrations found in tuberculosis patients. This protein augments inflammation in the presence of infection and inhibits inflammation in uninfected macrophages, protecting uninvolved lung segments from the deleterious effects of inflammation.

In Situ Activation of Helper T Cells in the Lung

ABSTRACT To better understand the lung and systemic responses of helper T cells mediating memory immunity to Mycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4+ lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purified-protein-derivative-negative subjects, and 7 purified-protein-derivative-positive subjects. In marked contrast to CD4+ lymphocytes from PB (9% ± 5% expressing CD45RA and CD29), the majority (55% ± 16%) of CD4+ lymphocytes in BAL (ALs) simultaneously expressed CD45RA, a naı̈ve T-cell marker, and CD29, members of the very late activation family. Further evaluation revealed that CD4+ ALs expressed both CD45RA and CD45RO, a memory T-cell marker. In addition, the proportion of CD4+ lymphocytes expressing CD69, an early activation marker, was drastically increased in BAL fluid (83% ± 9%) compared to PB (1% ± 1%), whereas no significant difference was seen in the expression of CD25, the low-affinity interleukin 2 receptor (34% ± 15% versus 40% ± 16%). More importantly, we identified a minor population of CD69bright CD25bright CD4+lymphocytes in BAL (10% ± 6%) that were consistently absent from PB (1% ± 1%). Thus, CD4+ lymphocytes in the lung paradoxically coexpress surface molecules characteristic of naı̈ve and memory helper T cells as well as surface molecules commonly associated with early and late stages of activation. No difference was observed for ALs obtained from TB-infected and uninfected lung segments in this regard. It remains to be determined if these surface molecules are induced by the alveolar environment or if CD4+ lymphocytes coexpressing this unusual combination of surface molecules are selectively recruited from the circulation. Our data suggest that ex vivo experiments on helper T-cell subsets that display distinctive phenotypes may be pivotal to studies on the human immune response to potential TB vaccines.

Aerosolized Gamma Interferon (IFN-γ) Induces Expression of the Genes Encoding the IFN-γ-Inducible 10-Kilodalton Protein but Not Inducible Nitric Oxide Synthase in the Lung during Tuberculosis

ABSTRACT Gamma interferon (IFN-γ) is critical in the immune response against Mycobacterium tuberculosis. In an ongoing trial of aerosol IFN-γ in conjunction with standard drug therapy, we have observed activation of IFN signaling in bronchoalveolar lavage (BAL) cells from tuberculosis (TB) patients. We hypothesized that aerosol IFN-γ treatment of pulmonary TB would increase expression of genes important for the control of TB. We investigated the expression of downstream genes by measuring inducible nitric oxide synthase (iNOS) and the chemokine IFN-inducible 10-kDa protein (IP-10) by real-time quantitative reverse transcription-PCR. In vitro, M. tuberculosis induced IP-10, and IFN-γ stimulated this further, with no effect on iNOS expression. We studied 21 patients with pulmonary TB and 7 healthy subjects. Similar to the in vitro model, IP-10 mRNA was increased in BAL cells from TB patients and was augmented after treatment with aerosolized IFN-γ. TB was also associated with elevated iNOS mRNA, but aerosolized IFN-γ did not further enhance expression. Genomic analysis identified 1,300 of 4,058 genes expressed in BAL cells from six TB patients before and after 1 month of therapy, including aerosolized IFN-γ. However, only 15 genes were differentially regulated by IFN-γ. We conclude that iNOS and IP-10 mRNA expression is increased in TB but that aerosol IFN-γ treatment increases expression of few genes in the human lung.

Mechanisms of Polymorphonuclear Neutrophil—Mediated Induction of HIV-1 Replication in Macrophages during Pulmonary Tuberculosis

BACKGROUND Pulmonary tuberculosis (TB) can present with polymorphonuclear neutrophil (PMN)-predominant alveolitis. TB accelerates acquired immunodeficiency syndrome by increasing human immunodeficiency virus type 1 (HIV-1) replication and mutation in alveolar macrophages. A 16-kDa CCAAAT/enhancer-binding protein beta (C/EBP beta ) isoform is a strong transcriptional repressor of the HIV long terminal repeat (LTR) in resting alveolar macrophages, leading to latent viral infection; its expression is lost during TB, derepressing the HIV LTR. METHODS Lung segments were sampled from HIV/Mycobacterium tuberculosis-coinfected patients by means of bronchoalveolar lavage. In vitro coculture experiments defined the mechanism of induction of HIV-1 infection in macrophages by PMNs. RESULTS Lung segments from patients with PMN-predominant TB had a markedly elevated viral load. Direct contact between activated PMNs and macrophages stimulated HIV-1 replication and LTR transcription and down-regulated inhibitory C/EBP beta . Isolated PMN membranes substituted for PMN contact, derepressing the HIV-1 LTR. The lipid raft fraction of PMN membranes expressed CD40 ligand (CD40L), CD28, and leukocyte function-associated antigen 1 (LFA-1 [i.e., CD11a and CD18]), and PMN activation increased lipid raft expression of CD40L and CD28. Blocking antibodies to CD40L, CD28, and LFA-1 inhibited PMN membrane-mediated HIV-1 LTR derepression. Alternately, cross-linking of macrophage receptors for CD40L, CD28, and LFA-1 (CD40, CD80/86, and intercellular adhesion molecule 1) abolished inhibitory C/EBP beta expression. CONCLUSION PMN-macrophage contact derepresses the HIV-1 LTR and enhances HIV-1 replication in alveolar macrophages during pulmonary TB. Derepression is mediated through costimulatory molecule signaling.

Significance of respiratory isolates of Mycobacterium avium complex in HIV positive and HIV negative patients

OBJECTIVE Mycobacterium avium complex (MAC) is isolated with increasing frequency from respiratory specimens. This study was an attempt to determine the significance of this in human immunodeficiency virus (HIV)-positive and HIV-negative patients. METHODS A retrospective cohort study was conducted at Bellevue Hospital, a large municipal hospital in New York City, including all patients with two or more respiratory tract specimens positive for MAC during the period January 1996 to October 1996. RESULTS Eighty patients met inclusion criteria. Forty-six were HIV-positive, and 34 were HIV-negative. Age, gender distribution, and race were comparable. Cough was a common complaint in all patients, whereas HIV-positive patients were significantly more likely to have fever (19 vs. 2, P < 0.0001). Abnormal chest radiographs were common in both groups (P > 0.8), although HIV-positive patients were more likely to have diffuse abnormalities (P < 0.0001). Focal radiographic findings were similar for both groups; however, there was a trend toward more lymphadenopathy in the HIV-positive group, though this did not reach statistical significance (P = 0.17). Notably, patients in both groups frequently had an established concurrent pulmonary diagnosis or evidence of disseminated MAC infection. Patients who were HIV-positive had Pneumocystis carinii pneumonia (n = 10), pneumonia (n = 10), and disseminated MAC disease (n = 12); whereas the concurrent disease in HIV-negative patients predominantly was active tuberculosis (n = 13). According to the recent American Thoracic Society-recommended criteria for the diagnosis of pulmonary disease caused by nontuberculous mycobacteria only 7 of 46 HIV-positive patients and 1 of 34 HIV-negative patients met clinical, bacteriologic, and radiographic criteria for pulmonary disease caused by MAC (P = 0.052). CONCLUSIONS Mycobacterium avium complex often is cultured from patients with other lung diseases, and its presence in sputum infrequently signifies true disease, though it is more likely to do so in HIV-positive patients.

Part of the RBM gene cluster is located distally to the DAZ gene cluster in human Yq11.23

Normal human Y and inverted Y chromosomes were chosen for physical fluorescence in situ hybridization (FISH) mapping of RBM and DAZ probes for the relative positioning of the RBM and DAZ gene clusters in interval 6 of the human Y chromosome. The inversion breakpoint in Yq11.23 turned out to be distal to the DAZ gene cluster, as the entire DAZ signal appears in the short arm of the inv(Y) chromosome. On the contrary, this inversion breakpoint in Yq11.23 divides the RBM signal cluster, leaving a weaker signal on the long arm while bringing the main RBM signal to the short arm of the inv(Y) chromosome. Thus, it can be concluded that, in contrast to previous claims, part of the RBM gene cluster is located distally to the DAZ gene cluster in deletion interval 6 of the human Y chromosome.Normal human Y and inverted Y chromosomes were chosen for physical ̄uorescence in situ hybridization (FISH) mapping of RBM and DAZ probes for the relative positioning of the RBM and DAZ gene clusters in interval 6 of the human Y chromosome. The inversion breakpoint in Yq11.23 turned out to be distal to the DAZ gene cluster, as the entire DAZ signal appears in the short arm of the inv(Y) chromosome. On the contrary, this inversion breakpoint in Yq11.23 divides the RBM signal cluster, leaving a weaker signal on the long arm while bringing the main RBM signal to the short arm of the inv(Y) chromosome. Thus, it can be concluded that, in contrast to previous claims, part of the RBM gene cluster is located distally to the DAZ gene cluster in deletion interval 6 of the human Y chromosome.