Neutrophils differentially attenuate immune response to Aspergillus infection through complement receptor 3 and induction of myeloperoxidase.

Invasive aspergillosis (IA) remains a major cause of morbidity in immunocompromised hosts. This is due to the inability of the host immunity to respond appropriately to Aspergillus. An established risk factor for IA is neutropenia that is encountered by patients undergoing chemotherapy. Herein, we investigate the role of neutrophils in modulating host response to Aspergillus. We found that neutrophils had the propensity to suppress proinflammatory cytokine production but through different mechanisms for specific cytokines. Cellular contact was requisite for the modulation of interleukin-1 beta production by Aspergillus with the involvement of complement receptor 3. On the other hand, inhibition of tumour necrosis factor-alpha production (TNF-α) was cell contact-independent and mediated by secreted myeloperoxidase. Specifically, the inhibition of TNF-α by myeloperoxidase was through the TLR4 pathway and involved interference with the mRNA transcription of TNF receptor-associated factor 6/interferon regulatory factor 5. Our study illustrates the extended immune modulatory role of neutrophils beyond its primary phagocytic function. The absence of neutrophils and loss of its inhibitory effect on cytokine production explains the hypercytokinemia seen in neutropenic patients when infected with Aspergillus.

Tissue penetration of antifungal agents.

Understanding the tissue penetration of systemically administered antifungal agents is critical for a proper appreciation of their antifungal efficacy in animals and humans. Both the time course of an antifungal drug and its absolute concentrations within tissues may differ significantly from those observed in the bloodstream. In addition, tissue concentrations must also be interpreted within the context of the pathogenesis of the various invasive fungal infections, which differ significantly. There are major technical obstacles to the estimation of concentrations of antifungal agents in various tissue subcompartments, yet these agents, even those within the same class, may exhibit markedly different tissue distributions. This review explores these issues and provides a summary of tissue concentrations of 11 currently licensed systemic antifungal agents. It also explores the therapeutic implications of their distribution at various sites of infection.

An elevated pro-inflammatory cytokine response is linked to development of amphotericin B-induced nephrotoxicity.

OBJECTIVES: The underlying mechanism for amphotericin B-induced acute kidney injury (AKI) remains poorly understood and may be immunologically mediated. We assessed whether the development of nephrotoxicity is linked to a distinct cytokine profile in patients receiving amphotericin B deoxycholate (AmBD). PATIENTS AND METHODS: In 58 patients who received AmBD, circulating serum interleukin (IL)-6, IL-8 and IL-10 were measured at baseline, week 1 and week 2 of antifungal treatment and correlated to the development of renal impairment. The Cox proportional hazards model approach was adopted for analysis. RESULTS: The P value was 0.026 for the overall effect of IL-6 on time to development of AKI. An increasing or non-receding IL-6 trend by week 1 of AmBD treatment (followed by a decreasing or non-receding IL-6 trend from week 1 to week 2) correlated with an increased likelihood of nephrotoxicity [hazard ratio (HR) 6.93, P value 0.005 and HR 3.46, P value 0.035, respectively]. Similarly, persistently increasing IL-8 levels were linked to a 3.84-fold increased likelihood of AKI. CONCLUSIONS: In patients receiving AmBD, persistence of an elevated pro-inflammatory cytokine milieu is associated with a predisposition to drug-related kidney injury.

Early serum galactomannan trend as a predictor of outcome of invasive aspergillosis.

The monitoring and prediction of treatment responses to invasive aspergillosis (IA) are difficult. We determined whether serum galactomannan index (GMI) trends early in the course of disease may be useful in predicting eventual clinical outcomes. For the subjects recruited into the multicenter Global Aspergillosis Study, serial GMIs were measured at baseline and at weeks 1, 2, and 4 following antifungal treatment. Clinical response and survival at 12 weeks were the outcome measures. GMI trends were analyzed by using the generalized estimation equation approach. GMI cutoffs were evaluated by using receiver-operating curve analyses incorporating pre- and posttest probabilities. Of the 202 study patients diagnosed with IA, 71 (35.1%) had a baseline GMI of ≥ 0.5. Week 1 GMI was significantly lower for the eventual responders to treatment at week 12 than for the nonresponders (GMIs of 0.62 ± 0.12 and 1.15 ± 0.22, respectively; P = 0.035). A GMI reduction of >35% between baseline and week 1 predicted a probability of a satisfactory clinical response. For IA patients with pretreatment GMIs of <0.5 (n = 131; 64.9%), GMI ought to remain low during treatment, and a rising absolute GMI to >0.5 at week 2 despite antifungal treatment heralded a poor clinical outcome. Here, every 0.1-unit increase in the GMI between baseline and week 2 increased the likelihood of an unsatisfactory clinical response by 21.6% (P = 0.018). In summary, clinical outcomes may be anticipated by charting early GMI trends during the first 2 weeks of antifungal therapy. These findings have significant implications for the management of IA.

Observational study of the clinical efficacy of voriconazole and its relationship to plasma concentrations in patients.

Voriconazole is approved for treating invasive fungal infections. We examined voriconazole exposure-response relationships for patients from nine published clinical trials. The relationship between the mean voriconazole plasma concentration (C(avg)) and clinical response and between the free C(avg)/MIC ratio versus the clinical response were explored using logistic regression. The impact of covariates on response was also assessed. Monte Carlo simulation was used to estimate the relationship between the trough concentration/MIC ratio and the probability of response. The covariates individually related to response were as follows: study (P < 0.001), therapy (primary/salvage, P < 0.001), primary diagnosis (P < 0.001), race (P = 0.004), baseline bilirubin (P < 0.001), baseline alkaline phosphatase (P = 0.014), and pathogen (yeast/mold, P < 0.001). The C(avg) for 72% of the patients was 0.5 to 5.0 µg/ml, with the maximum response rate (74%) at 3.0 to 4.0 µg/ml. The C(avg) showed a nonlinear relationship to response (P < 0.003), with a lower probability at the extremes. For patients with C(avg) < 0.5 µg/ml, the response rate was 57%. The lowest response rate (56%) was seen with a C(avg) ≥ 5.0 µg/ml (18% of patients) and was associated with significantly lower mold infection responses compared to yeasts (P < 0.001) but not with voriconazole toxicity. Higher free C(avg)/MIC ratios were associated with a progressively higher probability of response. Monte Carlo simulation suggested that a trough/MIC ratio of 2 to 5 is associated with a near-maximal probability of response. The probability of response is lower at the extremes of C(avg). Patients with higher free C(avg)/MIC ratios have a higher probability of clinical response. A trough/MIC ratio of 2 to 5 can be used as a target for therapeutic drug monitoring.

Early proinflammatory cytokines and C­reactive protein trends as predictors of outcome in invasive Aspergillosis.

BACKGROUND: Monitoring treatment response in invasive aspergillosis is challenging, because an immunocompromised host may not exhibit reliable symptoms and clinical signs. Cytokines play a pivotal role in mediating host immune response to infection; therefore, the profiling of biomarkers may be an appropriate surrogate for disease status. METHODS: We studied, in a cohort of 119 patients with invasive aspergillosis who were recruited in a multicenter clinical trial, serum interleukin (IL)-6, IL­8, IL­10, interferon­Î³, and C­reactive protein (CRP) trends over the first 4 weeks of therapy and correlated these trends to clinical outcome parameters. RESULTS: Circulating IL­6 and CRP levels were high at initiation of therapy and generally showed a downward trend with antifungal treatment. However, subjects with adverse outcomes exhibited a distinct lack of decline in IL­6 and CRP levels at week 1, compared with responders (P = .02, for both IL­6 and CRP). Nonresponders also had significantly elevated IL­8 levels (P = .001). CONCLUSIONS: High initial IL­8 and persistently elevated IL­6, IL­8, and CRP levels after initiation of treatment may be early predictors of adverse outcome in invasive aspergillosis. Cytokine and CRP profiles could be used for early identification of patients with a poor response to antifungal treatment who may benefit from more­aggressive antimicrobial regimens.

Pharmacokinetics and safety of 14 days intravenous voriconazole in allogeneic haematopoietic stem cell transplant recipients.

BACKGROUND: Voriconazole is used to manage invasive fungal diseases in recipients of an allogeneic haematopoietic stem cell transplant (HSCT) after myeloablative treatment. Little is known about the pharmacokinetics (PK) of voriconazole in this population, who also receive cyclosporine A. METHODS: Patients admitted for an allogeneic HSCT were eligible for the study. Voriconazole was given intravenously at 6 mg/kg twice daily on day 1, then 4 mg/kg twice daily until the day of transplant to reach steady-state conditions and then continued for a further week during which cyclosporine A was administered. Blood samples were drawn on the day of HSCT and daily for the next 14 days. PK curves were determined on days 7 and 14. PK parameters were calculated using non-compartmental analysis. CYP2C19*2 and CYP2C19*3 polymorphisms were also determined. RESULTS: Ten patients were fully evaluable. Median AUC(0-12) of voriconazole on the day of HSCT was 33.81 mg.h/L [interquartile range (IQR) 20.59-39.39] and 25.61 mg.h/L (IQR 22.48-38.65) 1 week later. AUC(0-12) of voriconazole on both days was similar to data reported for healthy volunteers. Trough levels were <1.0 mg/L for 3 of 10 patients on the day of HSCT and for 4 of 10 patients 1 week later. No difference in clearance of voriconazole was found between CYP2C19 extensive metabolizers (n = 4) and carriers of one non-functional allele (n = 6). CONCLUSIONS: Exposure and clearance of voriconazole in recipients of an allogeneic HSCT are similar to those of healthy volunteers though there was high intra- and inter-individual variation in drug exposures which may have implications for similar patient populations.

Association of mannose-binding lectin deficiency with acute invasive aspergillosis in immunocompromised patients.

BACKGROUND: Invasive aspergillosis is a devastating infection with attributable mortality of 40% despite antifungal therapy. In animal models of aspergillosis, deficiency of mannose-binding lectin (MBL), a pattern recognition receptor that activates complement, is a susceptibility factor. MBL deficiency occurs in 20%-30% of the population. We hypothesized that MBL deficiency may be a susceptibility factor for invasive aspergillosis in humans. METHODS: Serum MBL concentrations were measured by enzyme-linked immunosorbent assay in 65 patients with proven or probable acute invasive aspergillosis and 78 febrile immunocompromised control subjects. MBL concentrations and the frequency of MBL deficiency were compared. RESULTS: The median serum MBL level was significantly lower in patients with aspergillosis than in control subjects (281 ng/mL vs 835 ng/mL; P = .007). MBL deficiency (MBL concentration, <500 ng/mL) was significantly more common in patients with aspergillosis than control subjects (62% vs 32%; P < .001). Frequency of MBL deficiency was similar among patients with aspergillosis irrespective of response to antifungal therapy (P = .10). CONCLUSIONS: This study is the first, to our knowledge, to show an association between MBL deficiency and acute invasive aspergillosis in humans. Further study is required to investigate the causal nature of this association and to define whether diagnosis of MBL deficiency may identify immunocompromised patients at increased risk of invasive aspergillosis.

Imaging findings in acute invasive pulmonary aspergillosis: clinical significance of the halo sign.

BACKGROUND: Computed tomography (CT) of the chest may be used to identify the halo sign, a macronodule surrounded by a perimeter of ground-glass opacity, which is an early sign of invasive pulmonary aspergillosis (IPA). This study analyzed chest CT findings at presentation from a large series of patients with IPA, to assess the prevalence of these imaging findings and to evaluate the clinical utility of the halo sign for early identification of this potentially life-threatening infection. METHODS: Baseline chest CT imaging findings from 235 patients with IPA who participated in a previously published study were systematically analyzed. To evaluate the clinical utility of the halo sign for the early identification and treatment of IPA, we compared response to treatment and survival after 12 weeks of treatment in 143 patients who presented with a halo sign and in 79 patients with other imaging findings. RESULTS: At presentation, most patients (94%) had > or =1 macronodules, and many (61%) also had halo signs. Other imaging findings at presentation, including consolidations (30%), infarct-shaped nodules (27%), cavitary lesions (20%), and air-crescent signs (10%), were less common. Patients presenting with a halo sign had significantly better responses to treatment (52% vs. 29%; P<.001) and greater survival to 84 days (71% vs. 53%; P<.01) than did patients who presented with other imaging findings. CONCLUSIONS: Most patients presented with a halo sign and/or a macronodule in this large imaging study of IPA. Initiation of antifungal treatment on the basis of the identification of a halo sign by chest CT is associated with a significantly better response to treatment and improved survival.

Voriconazole versus amphotericin B for primary therapy of invasive aspergillosis.

BACKGROUND: Voriconazole is a broad-spectrum triazole that is active against aspergillus species. We conducted a randomized trial to compare voriconazole with amphotericin B for primary therapy of invasive aspergillosis. METHODS: In this randomized, unblinded trial, patients received either intravenous voriconazole (two doses of 6 mg per kilogram of body weight on day 1, then 4 mg per kilogram twice daily for at least seven days) followed by 200 mg orally twice daily or intravenous amphotericin B deoxycholate (1 to 1.5 mg per kilogram per day). Other licensed antifungal treatments were allowed if the initial therapy failed or if the patient had an intolerance to the first drug used. A complete or partial response was considered to be a successful outcome. RESULTS: A total of 144 patients in the voriconazole group and 133 patients in the amphotericin B group with definite or probable aspergillosis received at least one dose of treatment. In most of the patients, the underlying condition was allogeneic hematopoietic-cell transplantation, acute leukemia, or other hematologic diseases. At week 12, there were successful outcomes in 52.8 percent of the patients in the voriconazole group (complete responses in 20.8 percent and partial responses in 31.9 percent) and 31.6 percent of those in the amphotericin B group (complete responses in 16.5 percent and partial responses in 15.0 percent; absolute difference, 21.2 percentage points; 95 percent confidence interval, 10.4 to 32.9). The survival rate at 12 weeks was 70.8 percent in the voriconazole group and 57.9 percent in the amphotericin B group (hazard ratio, 0.59; 95 percent confidence interval, 0.40 to 0.88). Voriconazole-treated patients had significantly fewer severe drug-related adverse events, but transient visual disturbances were common with voriconazole (occurring in 44.8 percent of patients). CONCLUSIONS: In patients with invasive aspergillosis, initial therapy with voriconazole led to better responses and improved survival and resulted in fewer severe side effects than the standard approach of initial therapy with amphotericin B.

Voriconazole or amphotericin B as primary therapy yields distinct early serum galactomannan trends related to outcomes in invasive aspergillosis.

An improved number of anti-fungal drugs are currently available for the treatment of invasive aspergillosis (IA). While serial galactomannan index (GMI) measurement can be used to monitor response to treatment, the extent to which different anti-fungal regimens can affect galactomannan levels is unknown. In 147 IA patients receiving either voriconazole (VCZ) or conventional amphotericin B (CAB) in a multicentre clinical trial, we performed post-hoc analyses of GMI trends in relation to outcomes. The generalized estimation equations approach was used to estimate changes in the effect size for GMI over time within patients. Patients who received VCZ primary therapy and had good treatment response 12 weeks later showed earlier decreases in GMI values at Week 1 and Week 2 (p = 0.001 and 0.046 respectively) as compared to patients who only received CAB. At end-of-randomized therapy (EORT), which was a pre-set secondary assessment point for all patients who switched from randomized primary (CAB or VCZ) to an alternative anti-fungal drug, treatment failure was associated with increasing GMI at Weeks 1 and 2 in CAB-primary treated patients (p = 0.022 and 0.046 respectively). These distinct trends highlight the variations in GMI kinetics with the use of different anti-fungal drugs and their implications in relation to IA treatment response.