A strategy for prevention of fungal infections in lung transplantation: Role of bronchoalveolar lavage fluid galactomannan and fungal culture.

BACKGROUND: The optimal strategy for prevention of invasive fungal infections in lung transplant recipients remains undetermined. We studied strategies based on bronchoalveolar lavage fungal culture and galactomannan for prevention of invasive aspergillosis in lung transplant recipients. METHODS: Consecutive lung transplant recipients were evaluated during the period January 2010 to September 2014. Rates of invasive aspergillosis and all-cause mortality were recorded at 1 year. Criteria established by the International Society for Heart and Lung Transplantation were used to define invasive fungal infections. Multivariate Cox regression analyses were performed to assess the outcomes of mortality and invasive aspergillosis. RESULTS: A total of 519 lung transplant recipients with 3,077 bronchoscopies were included in our study. The cumulative incidence of fungal infections was 14% (75 of 519). Of these patients, 10.6% (54 of 519) developed Aspergillus-related clinical syndromes. Using multivariate analysis, pre-emptive therapy was associated with significantly lower rates of invasive aspergillosis at 1 year post-transplantation compared with no pre-emptive therapy (hazard ratio [HR] 0.23, 95% confidence interval [CI] 0.09 to 0.58). Pre-emptive therapy and invasive aspergillosis had similar mortality rates compared with no invasive aspergillosis, or negative culture and galactomannan at 1 year (HR 0.54, 95% CI 0.23 to 1.28; and HR 0.99, 95% CI 0.44 to 2.25, respectively). During follow-up, 50% (259 of 519) of patients were negative for galactomannan and Aspergillus culture in bronchoalveolar lavage, and did not receive anti-fungal treatment. Only 2 patients developed invasive aspergillosis in this cohort. CONCLUSIONS: Our study suggests that use of bronchoalveolar lavage culture and a galactomannan-directed pre-emptive approach significantly decreased the risk of invasive aspergillosis, allowing a 50% reduction in anti-fungal exposure compared with a universal prophylaxis approach, without affecting mortality at 1 year.

Pentraxin 3 levels in bronchoalveolar lavage fluid of lung transplant recipients with invasive aspergillosis.

BACKGROUND: Invasive aspergillosis is the most common invasive fungal infection in lung transplant recipients. The use of galactomannan testing in bronchoalveolar lavage (BAL) fluid has improved diagnosis of invasive aspergillosis; however, false-positive results can lead to overdiagnosis and unnecessary treatment. The use of proinflammatory markers such as pentraxin 3 (PTX3) may help differentiate between Aspergillus colonization and disease. METHODS: BAL PTX3 concentrations were measured by enzyme-linked immunosorbent assay in 151 lung transplant recipients and 9 healthy control subjects. Patients were characterized as having Aspergillus colonization or invasive disease according to International Society of Heart and Lung Transplantation criteria. Concomitant PTX3values were compared using Mann-Whitney U and Kruskal-Wallis tests. RESULTS: We analyzed 322 BAL stored samples and identified 15 invasive aspergillosis events, 38 Aspergillus colonizations, and 17 positive galactomannan with negative Aspergillus cultures. Median BAL PTX3 level was significantly higher in patients with invasive aspergillosis compared with patients with Aspergillus colonization and healthy control subjects (439.20 pg/ml [interquartile range (IQR) 168.18-778.90], 68.93 pg/ml [IQR 13.67-156.74], and 13.67 pg/ml [IQR 13.67-121.18]; p < 0.001). Patients with BAL PTX3 value >319 pg/ml with positive galactomannan and patients with BAL PTX3 value >312 pg/ml with positive Aspergillus culture were 4.5 and 5.5 times more likely to have invasive pulmonary aspergillosis, respectively. CONCLUSIONS: Our study shows that PTX3 measurements in BAL samples were significantly higher among patients with invasive aspergillosis and may help to identify patients with Aspergillus colonization and false-positive galactomannan in BAL samples.

Impaired T cell responsiveness to interleukin-6 in hematological patients with invasive aspergillosis.

Invasive mold infections (IMI) are among the most devastating complications following chemotherapy and hematopoietic stem cell transplantation (HSCT), with high mortality rates. Yet, the molecular basis for human susceptibility to invasive aspergillosis (IA) and mucormycosis remain poorly understood. Herein, we aimed to characterize the immune profile of individuals with hematological malignancies (n = 18) who developed IMI during the course of chemotherapy or HSCT, and compared it to that of hematological patients who had no evidence of invasive fungal infection (n = 16). First, we measured the expression of the pattern recognition receptors pentraxin 3, dectin-1, and Toll-like receptors (TLR) 2 and 4 in peripheral blood of chemotherapy and HSCT recipients with IMI. Compared to hematological controls, individuals with IA and mucormycosis had defective expression of dectin-1; in addition, patients with mucormycosis had decreased TLR2 and increased TLR4 expression. Since fungal recognition via dectin-1 favors T helper 17 responses and the latter are highly dependent on activation of the signal transducer and activator of transcription (STAT) 3, we next used phospho-flow cytometry to measure the phosphorylation of the transcription factors STAT1 and STAT3 in response to interferon-gamma (IFN-γ) and interleukin (IL)-6, respectively. While IFN-γ/STAT1 signaling was similar between groups, naïve T cells from patients with IA, but not those with mucormycosis, exhibited reduced responsiveness to IL-6 as measured by STAT3 phosphorylation. Furthermore, IL-6 increased Aspergillus-induced IL-17 production in culture supernatants from healthy and hematological controls but not in patients with IA. Altogether, these observations suggest an important role for dectin-1 and the IL-6/STAT3 pathway in protective immunity against Aspergillus.

Potential role of CC chemokine receptor 6 in prediction of late-onset cytomegalovirus infection following solid organ transplant.

CCR6 is a chemokine receptor involved in homing memory T cells, particularly Th17 cells, to sites of mucosal inflammation. Despite the critical role of memory T cells in long-term protective immunity against cytomegalovirus (CMV), a virus that reactivates at multiple mucosal sites, the ability of CCR6 or other Th17 marker expression to predict CMV reactivation following transplantation is not clear. Using 11-color flow cytometry, in this prospective single-center pilot study, we measured the expression of CCR6 and other markers of T-cell function in peripheral blood samples obtained from 21 SOT recipients at the time of discontinuation of anti-CMV prophylaxis. CMV viremia was monitored on a monthly basis after discontinuation of prophylaxis. Eleven patients (52%) developed CMV viremia during the six-month follow-up period. Late-onset CMV infection was preceded by an immune phenotype characterized by increased CCR6 expression on bulk CD4(+) T cells and a reduced number of circulating CMV IE-1-specific Th1 (CD4(+) IFN-γ(+)) cells. Among the markers evaluated, CCR6 was the best single predictor of late-onset CMV infection. Our results suggest that CCR6 expression at the time of discontinuation of antiviral prophylaxis might be a useful predictor of late-onset CMV reactivation and provide the basis for future larger prospective studies.

Electrochemical enzyme-linked immunosorbent assay featuring proximal reagent generation: detection of human immunodeficiency virus antibodies in clinical samples.

We describe a simple electrochemical immunoassay for human immunodeficiency virus (HIV) antibody detection that localizes capture and detection reagents in close proximity to a microelectrode. Antigenic peptides from HIV-1 gp41 or HIV-2 gp36 were covalently attached to a SU-8 substrate that also presented a template for the deposition of three-dimensional microelectrodes. The detection of HIV antibodies was achieved with an electrochemical immunoassay where an alkaline phosphatase conjugated secondary antibody reacts with p-aminophenyl phosphate (pAPP) to produce a redox-active product, p-aminophenol. The current derived from the oxidation of the reporter group increased linearly over a wide antibody concentration range (0.001-1 µg mL(-1)), with a detection limit of 1 ng mL(-1) (6.7 pM) for both HIV-1 and HIV-2. This level of sensitivity is clinically relevant, and the feasibility of this approach for clinical sample testing was also evaluated with HIV clinical patient samples, with excellent performance observed compared against a commercially available gold standard. This approach was used to develop the first electrochemical enzyme-linked immunosorbent assay (ELISA) to detect HIV in clinical samples, and excellent performance relative to a gold standard test was achieved.

Rapid and specific electrochemical detection of prostate cancer cells using an aperture sensor array.

A rapid, simple and specific cancer cell counting sensor would allow for early detection and better disease management. We have developed a novel cell counting device that can specifically count 125 prostate cancer cells in both complex media with serum and a mixed cell population containing non-target cells within 15 min. The microfabricated glass chip with exposed gold apertures utilizes the anti-EpCAM antibody to selectively count prostate cancer cells via differential pulse voltammetry. The newly developed sensor exhibits excellent sensitivity and selectivity. The cells remain viable throughout the counting process and can be used for further analysis. This device could have utility for future applications in early stage cancer diagnosis.