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.

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.