Kenneth S. Knox

Differential Th17 CD4 T-cell depletion in pathogenic and nonpathogenic lentiviral infections

Acute HIV infection is characterized by massive loss of CD4 T cells from the gastrointestinal (GI) tract. Th17 cells are critical in the defense against microbes, particularly at mucosal surfaces. Here we analyzed Th17 cells in the blood, GI tract, and broncheoalveolar lavage of HIV-infected and uninfected humans, and SIV-infected and uninfected sooty mangabeys. We found that (1) human Th17 cells are specific for extracellular bacterial and fungal antigens, but not common viral antigens; (2) Th17 cells are infected by HIV in vivo, but not preferentially so; (3) CD4 T cells in blood of HIV-infected patients are skewed away from a Th17 phenotype toward a Th1 phenotype with cellular maturation; (4) there is significant loss of Th17 cells in the GI tract of HIV-infected patients; (5) Th17 cells are not preferentially lost from the broncheoalveolar lavage of HIV-infected patients; and (6) SIV-infected sooty mangabeys maintain healthy frequencies of Th17 cells in the blood and GI tract. These observations further elucidate the immunodeficiency of HIV disease and may provide a mechanistic basis for the mucosal barrier breakdown that characterizes HIV infection. Finally, these data may help account for the nonprogressive nature of nonpathogenic SIV infection in sooty mangabeys.

An Official American Thoracic Society Statement: Treatment of Fungal Infections in Adult Pulmonary and Critical Care Patients

With increasing numbers of immune-compromised patients with malignancy, hematologic disease, and HIV, as well as those receiving immunosupressive drug regimens for the management of organ transplantation or autoimmune inflammatory conditions, the incidence of fungal infections has dramatically increased over recent years. Definitive diagnosis of pulmonary fungal infections has also been substantially assisted by the development of newer diagnostic methods and techniques, including the use of antigen detection, polymerase chain reaction, serologies, computed tomography and positron emission tomography scans, bronchoscopy, mediastinoscopy, and video-assisted thorascopic biopsy. At the same time, the introduction of new treatment modalities has significantly broadened options available to physicians who treat these conditions. While traditionally antifungal therapy was limited to the use of amphotericin B, flucytosine, and a handful of clinically available azole agents, current pharmacologic treatment options include potent new azole compounds with extended antifungal activity, lipid forms of amphotericin B, and newer antifungal drugs, including the echinocandins. In view of the changing treatment of pulmonary fungal infections, the American Thoracic Society convened a working group of experts in fungal infections to develop a concise clinical statement of current therapeutic options for those fungal infections of particular relevance to pulmonary and critical care practice. This document focuses on three primary areas of concern: the endemic mycoses, including histoplasmosis, sporotrichosis, blastomycosis, and coccidioidomycosis; fungal infections of special concern for immune-compromised and critically ill patients, including cryptococcosis, aspergillosis, candidiasis, and Pneumocystis pneumonia; and rare and emerging fungal infections.

Histoplasmosis-Associated Cross-Reactivity in the BioRad Platelia Aspergillus Enzyme Immunoassay

ABSTRACT We observed false-positive results in the Platelia Aspergillus enzyme-linked immunoassay (EIA) for specimens from patients with histoplasmosis and mice with experimental infection. Platelia Aspergillus EIA-positive specimens were negative in the second-generation Histoplasma antigen EIA. Care must be taken to exclude histoplasmosis for patients with positive Platelia Aspergillus EIA results.

Widespread colonization of the lung by Tropheryma whipplei in HIV infection

RATIONALE Lung infections caused by opportunistic or virulent pathogens are a principal cause of morbidity and mortality in HIV infection. It is unknown whether HIV infection leads to changes in basal lung microflora, which may contribute to chronic pulmonary complications that increasingly are being recognized in individuals infected with HIV. OBJECTIVES To determine whether the immunodeficiency associated with HIV infection resulted in alteration of the lung microbiota. METHODS We used 16S ribosomal RNA targeted pyrosequencing and shotgun metagenomic sequencing to analyze bacterial gene sequences in bronchoalveolar lavage (BAL) and mouths of 82 HIV-positive and 77 HIV-negative subjects. MEASUREMENTS AND MAIN RESULTS Sequences representing Tropheryma whipplei, the etiologic agent of Whipples disease, were significantly more frequent in BAL of HIV-positive compared with HIV-negative individuals. T. whipplei dominated the community (>50% of sequence reads) in 11 HIV-positive subjects, but only 1 HIV-negative individual (13.4 versus 1.3%; P = 0.0018). In 30 HIV-positive individuals sampled longitudinally, antiretroviral therapy resulted in a significantly reduced relative abundance of T. whipplei in the lung. Shotgun metagenomic sequencing was performed on eight BAL samples dominated by T. whipplei 16S ribosomal RNA. Whole genome assembly of pooled reads showed that uncultured lung-derived T. whipplei had similar gene content to two isolates obtained from subjects with Whipples disease. CONCLUSIONS Asymptomatic subjects with HIV infection have unexpected colonization of the lung by T. whipplei, which is reduced by effective antiretroviral therapy and merits further study for a potential pathogenic role in chronic pulmonary complications of HIV infection.

Gene expression profiling identifies MMP-12 and ADAMDEC1 as potential pathogenic mediators of pulmonary sarcoidosis

RATIONALE Little is known about the genetic regulation of granulomatous inflammation in sarcoidosis. OBJECTIVES To determine if tissue gene array analysis would identify novel genes engaged in inflammation and lung remodeling in patients with sarcoidosis. METHODS Gene expression analysis was performed on tissues obtained from patients with sarcoidosis at the time of diagnosis (untreated) (n = 6) compared with normal lung tissue (n = 6). Expression of select genes was further confirmed in lung tissue from a second series of patients with sarcoidosis and disease-free control subjects (n = 11 per group) by semi-quantitative RT-PCR. Interactive gene networks were identified in patients with sarcoidosis using Ingenuity Pathway Analysis (Ingenuity Systems, Inc., Redwood, CA) software. The expression of proteins corresponding to selected overexpressed genes was determined using fluorokine multiplex analysis, and immunohistochemistry. Selected genes and proteins were then analyzed in bronchoalveolar lavage fluid in an independent series of patients with sarcoidosis (n = 36) and control subjects (n = 12). MEASUREMENTS AND MAIN RESULTS A gene network engaged in Th1-type responses was most significantly overexpressed in the sarcoidosis lung tissues, including genes not previously reported in the context of sarcoidosis (e.g., IL-7). MMP-12 and ADAMDEC1 transcripts were most highly expressed (> 25-fold) in sarcoidosis lung tissues, corresponding with increased protein expression by immunohistochemistry. MMP-12 and ADAMDEC1 gene and protein expression were increased in bronchoalveolar lavage samples from patients with sarcoidosis, correlating with disease severity. CONCLUSIONS Tissue gene expression analyses provide novel insights into the pathogenesis of pulmonary sarcoidosis. MMP-12 and ADAMDEC1 emerge as likely mediators of lung damage and/or remodeling and may serve as markers of disease activity.

Performance Characteristics of the Platelia Aspergillus Enzyme Immunoassay for Detection of Aspergillus Galactomannan Antigen in Bronchoalveolar Lavage Fluid

ABSTRACT We have evaluated the Platelia Aspergillus enzyme immunoassay for detection of galactomannan in bronchoalveolar lavage (BAL) specimens in solid organ transplant patients with aspergillosis. The precision and reproducibility in serum or BAL to which galactomannan was added were similar. Sensitivity was 81.8% in patients with aspergillosis, and specificity was 95.8% in lung transplant patients who underwent BAL for surveillance for infection or rejection. Among transplant controls, positive results were more common in patients (i) who underwent diagnostic BAL performed for evaluation of symptoms or chest computed tomographic abnormalities, (ii) who had undergone lung transplantation, or (iii) who were colonized with Aspergillus. Galactomannan testing in BAL is useful for diagnosis of aspergillosis in transplant patients. The significance of positive results in patients without confirmed aspergillosis requires further evaluation.

High frequencies of polyfunctional HIV-specific T cells are associated with preservation of mucosal CD4 T cells in bronchoalveolar lavage

The mechanisms underlying the massive gastrointestinal tract CD4 T-cell depletion in human immunodeficiency virus (HIV) infection are not well understood nor is it clear whether similar depletion is manifest at other mucosal surfaces. Studies of T-cell and virus dynamics in different anatomical sites have begun to illuminate the pathogenesis of HIV-associated disease. Here, we studied depletion and HIV infection frequencies of CD4 T cells from the gastrointestinal tract, bronchoalveolar lavage (BAL), and blood with the frequencies and functional profiles of HIV-specific T cells in these anatomically distinct sites in HIV-infected individuals. The major findings to emerge were as follows: (i) depletion of gastrointestinal CD4 T cells is associated with high frequencies of infected CD4 T cells; (ii) HIV-specific T cells are present at low frequencies in the gastrointestinal tract compared to blood; (iii) BAL CD4 T cells are not massively depleted during the chronic phase; (iv) infection frequencies of BAL CD4 T cells are similar to those in blood; (v) significantly higher frequencies and increased functionality of HIV-specific T cells were observed in BAL compared to blood. Taken together, these data suggest mechanisms for mucosal CD4 T-cell depletion and interventions that might circumvent global depletion of mucosal CD4 T cells.

HIV associated pulmonary emphysema: a review of the literature and inquiry into its mechanism

Chronic lung diseases are increasingly recognised complications of the human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS). Of these, pulmonary emphysema, characterised by permanent destruction of the lung parenchyma distal to the terminal bronchioles accompanied by various degrees of inflammation, is emerging as a distinct source of morbidity for patients infected with HIV. Similarly, HIV is now frequently cited as a susceptibility factor for the development of emphysema, independent of cigarette smoking status. The presence of common coexistent confounding factors that may predispose patients to chronic lung injury such as drugs, opportunistic infections and malnutrition, limits the scope of studies of direct mechanisms involved in HIV associated emphysematous lung disease. We review the clinical studies supporting a direct association between HIV infection and emphysema. Recent developments in the basic understanding of HIV infection and emphysema are also reviewed, since they may aid in understanding the pathobiology of HIV associated emphysema. The authors emphasise how HIV infection may affect cytotoxic lymphocyte activation, lung capillary endothelial cell injury and apoptosis, sphingolipid imbalance and oxidative stress in the lung. A better understanding of the pathogenesis of HIV associated pulmonary emphysema may provide clues and therapeutic targets that have broader application in this disease, including cigarette smoke induced emphysema.

Plasmalyte as a Cause of False-Positive Results for Aspergillus Galactomannan in Bronchoalveolar Lavage Fluid

The detection of galactomannan (GM) in the serum of immunocompromised patients is widely used for the early diagnosis of invasive aspergillosis ([6][1]). The test may also be useful when applied to bronchoalveolar lavage (BAL) fluid specimens for clinical diagnosis ([5][2]), though not FDA approved

Diagnosis of Histoplasmosis by Antigen Detection in BAL Fluid

BACKGROUND Detection of antigen in BAL is useful for diagnosis of histoplasmosis. The MVista Histoplasma antigen enzyme immunoassay has been modified to permit quantification. The purpose of this study is to compare the sensitivity of the quantitative antigen detection assay with cytopathology and culture of BAL specimens. METHODS BAL from patients with histoplasmosis who were evaluated at the Indiana University Medical Center and controls without histoplasmosis were studied. BAL fluid was tested in the quantitative Histoplasma antigen assay. RESULTS Antigen was detected in the BAL in 93.5% of patients with histoplasmosis, 80% with blastomycosis, and 0% of controls with nonfungal infections. Antigen was detected in the urine of 79% and serum in 65% of patients with histoplasmosis. Cytopathology was positive in 48% and culture in 48% of patients with histoplasmosis, and 40% and 60% of patients with blastomycosis, respectively. Serology was positive in 65%. Combining BAL antigen detection and BAL cytopathology, both methods for rapid diagnosis, the sensitivity was 96.8% in histoplasmosis and 80% in blastomycosis. CONCLUSIONS Detection of antigen in BAL complements antigen detection in serum and urine as an objective diagnostic test for histoplasmosis.