TREM1 regulates antifungal immune responses in invasive pulmonary aspergillosis.

Pattern recognition receptors (PRRs) are responsible for Aspergillus fumigatus recognition by innate immunity and its subsequent immune signaling. The triggering receptor expressed on myeloid cells 1 (TREM1) is a recently characterized pro-inflammatory receptor constitutively expressed on the surface of neutrophils and macrophages. A soluble form (sTREM1) of this protein that can be detected in human body fluids has been identified. Here we investigated the role of TREM1 during invasive pulmonary aspergillosis (IPA). IPA patients displayed significantly higher levels of sTREM1 in bronchoalveolar lavages when compared to control patients. Functional analysis in TREM1 showed that the levels of sTREM1 and TREM1 pathway-related cytokines were influenced by single nucleotide polymorphisms in TREM1. In addition, we confirmed a role of TREM1 on antifungal host defense against A. fumigatus in a murine model of IPA. TREM1 deficiency increased susceptibility to infection in the immunosuppressed murine host. Deletion of TREM1 showed delayed innate and adaptive immune responses and impaired pro-inflammatory cytokine responses. The absence of TREM1 in primary macrophages attenuated the TLR signaling by altering the expression of both receptor and effector proteins that are critical to the response against A. fumigatus. In this study, and for the first time, we demonstrate the key role for the TREM1 receptor pathway during IPA.

Polymorphisms within the ARNT2 and CX3CR1 Genes Are Associated with the Risk of Developing Invasive Aspergillosis.

Invasive aspergillosis (IA) is a life-threatening infection that affects an increasing number of patients undergoing chemotherapy or allo-transplantation, and recent studies have shown that genetic factors contribute to disease susceptibility. In this two-stage, population-based, case-control study, we evaluated whether 7 potentially functional single nucleotide polymorphisms (SNPs) within the ARNT2 and CX3CR1 genes influence the risk of IA in high-risk hematological patients. We genotyped selected SNPs in a cohort of 500 hematological patients (103 of those had been diagnosed with proven or probable IA), and we evaluated their association with the risk of developing IA. The association of the most interesting markers of IA risk was then validated in a replication population, including 474 subjects (94 IA and 380 non-IA patients). Functional experiments were also performed to confirm the biological relevance of the most interesting markers. The meta-analysis of both populations showed that carriers of the ARNT2rs1374213G, CX3CR1rs7631529A, and CX3CR1rs9823718G alleles (where the RefSeq identifier appears as a subscript) had a significantly increased risk of developing IA according to a log-additive model (P value from the meta-analysis [PMeta] = 9.8 · 10-5, PMeta = 1.5 · 10-4, and PMeta =7.9 · 10-5, respectively). Haplotype analysis also confirmed the association of the CX3CR1 haplotype with AG CGG with an increased risk of IA (P = 4.0 · 10-4). Mechanistically, we observed that monocyte-derived macrophages (MDM) from subjects carrying the ARNTR2rs1374213G allele or the GG genotype showed a significantly impaired fungicidal activity but that MDM from carriers of the ARNT2rs1374213G and CX3CR1rs9823718G or CX3CR1rs7631529A alleles had deregulated immune responses to Aspergillus conidia. These results, together with those from expression quantitative trait locus (eQTL) data browsers showing a strong correlation of the CX3CR1rs9823718G allele with lower levels of CX3CR1 mRNA in whole peripheral blood (P = 2.46 · 10-7) and primary monocytes (P = 4.31 · 10-7), highlight the role of the ARNT2 and CX3CR1 loci in modulating and predicting IA risk and provide new insights into the host immune mechanisms involved in IA development.

Using routine blood parameters to anticipate clinical outcomes in invasive aspergillosis.

OBJECTIVE: In invasive aspergillosis (IA), monitoring response to antifungal treatment is challenging. We aimed to explore if routine blood parameters help to anticipate outcomes following IA. METHODS: Post hoc secondary analysis of two multicenter randomized trials was performed. The Global Comparative Aspergillosis Study (GCA, n = 123) and the Combination Antifungal Study (CAS, n = 251) constituted the discovery and validation cohorts respectively. The outcome measures were response to treatment and survival to 12 weeks. Interval platelet, galactomannan index (GMI) and C-reactive protein (CRP) levels prior and during antifungal treatment were analysed using logistic regression, Kaplan-Meier survival and receiver operating characteristic (ROC) analyses. RESULTS: The 12-week survival was 70.7% and 63.7% for the GCA and CAS cohorts respectively. In the GCA cohort, every 10 × 109/L platelet count increase at week 2 and 4 improved 12-week survival odds by 6-18% (odds ratio (OR) 1.06-1.18, 95% confidence interval (CI) 1.02-1.33). Survival odds also improved 13% with every 10 mg/dL CRP drop at week 1 and 2 (OR 0.87, 95% CI 0.78-0.97). In the CAS cohort, week 2 platelet count was also associated with 12-week survival with 10% improved odds for every 10 × 109/L platelet increase (OR, 1.10, 95% CI 1.04-1.15). A GMI drop of 0.1 unit was additionally found to increase the odds of treatment response by 3% at the baseline of week 0 (OR 0.97, 95% CI 0.95-0.99). Week 2 platelet and CRP levels performed better than GMI on ROC analyses for survival (area under ROC curve 0.76, 0.87 and 0.67 respectively). A baseline platelet count higher than 30 × 109/L clearly identified patients with >75% survival probability. CONCLUSIONS: Higher serial platelets were associated with overall survival while GMI trends were linked to IA treatment response. Routine and simple laboratory indices may aid follow-up of response in IA patients.

Pharmacokinetics of extended dose intervals of micafungin in haematology patients: optimizing antifungal prophylaxis.

Background: Extended dosing intervals for micafungin could overcome the need for hospitalization for antifungal prophylaxis. Objectives: This multicentre, open-label, randomized trial compared the pharmacokinetics of 300 mg of micafungin given twice weekly with 100 mg once daily as antifungal prophylaxis in adult haematology patients at risk of developing invasive fungal disease. Secondary objectives were assessment of adequate exposure with an alternative dosing regimen of micafungin (700 mg once weekly) through Monte Carlo simulations and assessment of safety in this patient population. Patients and methods: Twenty adult patients were randomized to receive either 300 mg of micafungin twice weekly or 100 mg once daily for 8 days. Blood samples were drawn daily and pharmacokinetic curves were determined on days 4/5 and 8. Monte Carlo simulations were performed for both investigated regimens as well as a frequently proposed alternative regimen (700 mg once weekly). Results: The predicted median AUC0-168h (IQR) for a typical patient on the investigated regimens of 100 mg once daily and 300 mg twice weekly and the hypothetical regimen of 700 mg once weekly were 690 (583-829), 596 (485-717) and 704 (585-833) mg·h/L, respectively. Conclusions: We observed comparable exposure with 300 mg of micafungin twice weekly and 100 mg of micafungin once daily. We provide the pharmacokinetic proof for an extended dosing regimen, which now needs to be tested in a clinical trial with hard endpoints.

PCR-based detection of Aspergillus fumigatus Cyp51A mutations on bronchoalveolar lavage: a multicentre validation of the AsperGenius assay® in 201 patients with haematological disease suspected for invasive aspergillosis.

OBJECTIVES: In patients with invasive aspergillosis (IA), fungal cultures are mostly negative. Consequently, azole resistance often remains undetected. The AsperGenius® multiplex real-time PCR assay identifies clinically relevant Aspergillus species and four resistance-associated mutations (RAMs; TR34/L98H/T289A/Y121F) in the Cyp51A gene. This multicentre study evaluated the diagnostic performance of this assay on bronchoalveolar lavage (BAL) fluid and correlated the presence of RAMs with azole treatment failure and mortality. METHODS: Stored BAL samples from patients with haematological diseases with suspected IA were used. BAL samples that were galactomannan/culture positive were considered positive controls for the presence of Aspergillus. Azole treatment failure and 6 week mortality were compared in patients with and without RAMs that had received ≥5 days of voriconazole monotherapy. RESULTS: Two hundred and one patients each contributed one BAL sample, of which 88 were positive controls and 113 were negative controls. The optimal cycle threshold cut-off value for the Aspergillus species PCR was <38. With this cut-off, the PCR was positive in 74/88 positive controls. The sensitivity, specificity, positive predictive value and negative predictive value were 84%, 80%, 76% and 87%, respectively. 32/74 BAL samples were culture negative. Azole treatment failure was observed in 6/8 patients with a RAM compared with 12/45 patients without RAMs (P = 0.01). Six week mortality was 2.7 times higher in patients with RAMs (50.0% versus 18.6%; P = 0.07). CONCLUSIONS: The AsperGenius® assay had a good diagnostic performance on BAL and differentiated WT from Aspergillus fumigatus with RAMs, including in culture-negative BAL samples. Most importantly, detection of RAMs was associated with azole treatment failure.

Diagnostic Performance of Galactomannan Antigen Testing in Cerebrospinal Fluid.

Testing cerebrospinal fluid (CSF) for the presence of galactomannan (GM) antigen may help in diagnosing cerebral aspergillosis (CA). However, the use of the CSF GM test as a diagnostic test has been little studied. We evaluated its diagnostic performance by comparing the CSF GM optical density indexes (ODI) at different cutoffs in patients with probable and proven CA to those in patients without CA. Patients from 2 tertiary referral hospitals with suspected CA between 2004 and 2014 and in whom CSF GM ODI had been determined were selected. European Organization for Research and Treatment of Cancer/Invasive Infectious Diseases Study Mycoses Group (EORTC/MSG) definitions of invasive aspergillosis and CA were used, but with the exclusion of the test to be validated (i.e., the CSF GM test) as a microbiological EORTC/MSG criterion. The study population consisted of 44 patients (4 with proven CA, 13 with probable CA, and 27 with no CA). Of the 17 patients with CA, 15 had a CSF GM ODI of ≥2.0. Of 27 patients without CA, 26 had a CSF GM ODI of <0.5 and 1 had a CSF GM ODI of 8.2. When a GM CSF ODI cutoff of 1.0 was used, the sensitivity, specificity, and positive and negative predictive values were 88.2%, 96.3%, 93.8%, and 92.9%, respectively. The same results were found when a CSF GM ODI cutoff of 0.5 or 2.0 was used. Testing GM in CSF has a high diagnostic performance for diagnosing CA and may be useful to diagnose or virtually rule out the infection without the need for a cerebral biopsy.

Efficacy of caspofungin as salvage therapy for invasive aspergillosis compared to standard therapy in a historical cohort.

In a non-comparative study, caspofungin was effective salvage therapy for approximately half of the patients refractory to or intolerant of standard antifungal agents for invasive aspergillosis. To establish a frame of reference for these results, we compared the response to caspofungin with responses to other antifungal agents in a historical cohort of similar patients. The efficacy could be evaluated in 83 patients who received caspofungin 50 mg daily after a 70-mg loading dose. The historical control group, identified through a retrospective review of medical records, included 214 evaluable patients possibly refractory to or intolerant of ≥1 week of standard antifungal therapy. All patients had documented invasive aspergillosis. Favorable response was defined as a complete or partial response to therapy. Underlying diseases, baseline neutropenia, corticosteroid use, and sites of infection were similar in both studies. Most patients had received amphotericin B formulations and/or itraconazole, and were refractory to standard therapy. Favorable response rates were 45% with caspofungin and 16% with standard therapy. The unadjusted odds ratio for a favorable response (caspofungin/standard therapy) was 4.1 (95% confidence interval: 2.2, 7.5). After adjusting for potential imbalances in the frequency of disseminated infection, neutropenia, steroid use, and bone marrow transplantation between groups, the odds ratio remained at 4.1 (2.1, 7.9). Although only tentative conclusions about relative efficacy can be drawn from retrospective comparisons, caspofungin appeared to be at least as efficacious as an amphotericin B formulation and/or itraconazole for the treatment of invasive aspergillosis in patients refractory to or intolerant of their initial antifungal therapy.

History of the development of azole derivatives.

Until the 1940s, relatively few agents were available for the treatment of systemic fungal infections. The development of the polyene antifungals represented a major advance in medical mycology. Although amphotericin B quickly became the mainstay of therapy for serious infections, its use was associated with infusion-related side-effects and dose-limiting nephrotoxicity. The continued search for new and less toxic antifungals led to the discovery of the azoles several decades later. Ketoconazole, the first available compound for the oral treatment of systemic fungal infections, was released in the early 1980s. For almost a decade, ketoconazole was regarded as the drug of choice in nonlife-threatening endemic mycoses. The introduction of the first-generation triazoles represented a second major advance in the treatment of fungal infections. Both fluconazole and itraconazole displayed a broader spectrum of antifungal activity than the imidazoles and had a markedly improved safety profile compared with amphotericin B and ketoconazole. Despite widespread use, however, these agents became subject to a number of clinically important limitations related to their suboptimal spectrum of activity, the development of resistance, the induction of hazardous drug-drug interactions, their less than optimal pharmacokinetic profile (itraconazole capsules), and toxicity. In order to overcome these limitations, several analogues have been developed. These so-called 'second-generation' triazoles, including voriconazole, posaconazole and ravuconazole, have greater potency and possess increased activity against resistant and emerging pathogens, in particular against Aspergillus spp. If the toxicity profile of these agents is comparable to or better than that of the first-generation triazoles and drug interactions remain manageable, then these compounds represent a true expansion of our antifungal arsenal.

The use of polyclonal intravenous immunoglobulins in the prevention and treatment of infectious diseases.

In this review we discuss the prevention and treatment of infectious diseases with intravenous immunoglobulins (IVIG). IVIG can be used to prevent infections in primary as well as in certain secondary immunodeficiencies. We also discuss the use of IVIG in the prevention of CMV-disease after organ or bone marrow transplantation. Besides their use in prevention, IVIG can also be used as an additional therapy in sepsis in neonates, in streptococcal toxic shock syndrome and in CMV-disease after bone marrow or solid organ transplantation. We briefly discuss the different preparations of IVIG that are available in Belgium.

Fungal cell wall inhibitors: emphasis on clinical aspects.

Invasive fungal infections, mainly caused by Candida and Aspergillus species, are an emerging cause of morbidity and mortality among all categories of immunocompromised patients. Currently available antifungal agents, both polyenes, flucytosine and (tri)azoles are hampered by serious infusion- or drug-related toxicity, by hazardous drug-drug interactions, or by pharmacokinetic problems and by the development of resistance, in vitro as well as in vivo. In recent years, several companies have become interested in antifungal drug development and have launched new compounds into preclinical and clinical trials. Some of these agents target the fungal cell wall in stead of the cell membrane. They exert their fungicidal action through inhibition of the synthesis of critical compounds of that fungal cell wall, not present in mammalian cells. Exciting and promising agents include inhibitors of beta-(1,3)-D-glucan synthase and inhibitors of chitin synthase. These drugs appear well tolerated in Phase I-II studies and will soon enter Phase III studies. This review wants to provide the clinical framework for assessing the utility of these agents compared to existing antifungals, thereby focusing on invasive fungal disease and emphasising the changing fungal epidemiology and susceptibility in immunocompromised hosts.

Sch-27899 (Schering-Plough Corp).

Sch27899 (Ziracin) is an oligosaccharide antibiotic under development by Schering-Plough as a potential treatment for Gram-positive bacterial infection, including vancomycin- and methicillin-resistant bacteria. It is being evaluated in phase III clinical trials. Sch-27899 is a member of the naturally occurring class of everninomicins and was isolated from Micromonospora. Sch-27899 and the Micromonospora strain producing it were first disclosed in US04597968. The cyclodextrin complex, which overcomes the toxicity problems of Sch27899, is claimed in EP00538011.

Antifungal prophylaxis in neutropenia.

Despite the widespread prophylactic use of antifungal agents in neutropenic patients, invasive fungal infections continue to emerge as major causes of morbidity and mortality. With the exception of fluconazole prophylaxis in allogeneic marrow transplant recipients, no firm conclusions can be drawn due to the lack of reliable, randomized trials. At the present time, it seems that antifungal chemoprophylaxis is more a matter of faith rather than science. Earlier diagnosis based on noninvasive diagnostic techniques and pre-emptive strategies may offer more promise than a liberal prophylactic approach.