Experimental evidence that granulocyte transfusions are efficacious in treatment of neutropenic hosts with pulmonary aspergillosis

Exploiting antifungal immunity in the clinical context

The continuous expansion of immunocompromised patient populations at-risk for developing life-threatening opportunistic fungal infections in recent decades has helped develop a deeper understanding of antifungal host defenses, which has provided the foundation for eventually devising immune-based targeted interventions in the clinic. This review outlines how genetic variation in certain immune pathway-related genes may contribute to the observed clinical variability in the risk of acquisition and/or severity of fungal infections and how immunogenetic-based patient stratification may enable the eventual development of personalized strategies for antifungal prophylaxis and/or vaccination. Moreover, this review synthesizes the emerging cytokine-based, cell-based, and other immunotherapeutic strategies that have shown promise as adjunctive therapies for boosting or modulating tissue-specific antifungal immune responses in the context of opportunistic fungal infections.

Transfusable neutrophil progenitors as cellular therapy for the prevention of invasive fungal infections

The use of mature neutrophil (granulocyte) transfusions for the treatment of neutropenic patients with invasive fungal infections (IFIs) has been the focus of multiple clinical trials. Despite these efforts, the transfusion of mature neutrophils has resulted in limited clinical benefit, likely owing to problems of insufficient numbers and the very short lifespan of these donor cells. In this report, we employed a system of conditionally immortalized murine neutrophil progenitors that are capable of continuous expansion, allowing for the generation of unlimited numbers of homogenous granulocyte-macrophage progenitors (GMPs). These GMPs were assayed in vivo to demonstrate their effect on survival in 2 models of IFI: candidemia and pulmonary aspergillosis. Mature neutrophils derived from GMPs executed all cardinal functions of neutrophils. Transfused GMPs homed to the bone marrow and spleen, where they completed normal differentiation to mature neutrophils. These neutrophils were capable of homing and extravasation in response to inflammatory stimuli using a sterile peritoneal challenge model. Furthermore, conditionally immortalized GMP transfusions significantly improved survival in models of candidemia and pulmonary aspergillosis. These data confirm the therapeutic benefit of prophylactic GMP transfusions in the setting of neutropenia and encourage development of progenitor cellular therapies for the management of fungal disease in high-risk patients.

Scedosporium and Lomentospora: an updated overview of underrated opportunists

Species of Scedosporium and Lomentospora are considered as emerging opportunists, affecting immunosuppressed and otherwise debilitated patients, although classically they are known from causing trauma-associated infections in healthy individuals. Clinical manifestations range from local infection to pulmonary colonization and severe invasive disease, in which mortality rates may be over 80%. These unacceptably high rates are due to the clinical status of patients, diagnostic difficulties, and to intrinsic antifungal resistance of these fungi. In consequence, several consortia have been founded to increase research efforts on these orphan fungi. The current review presents recent findings and summarizes the most relevant points, including the Scedosporium/Lomentospora taxonomy, environmental distribution, epidemiology, pathology, virulence factors, immunology, diagnostic methods, and therapeutic strategies.

Immune responses to invasive aspergillosis: new understanding and therapeutic opportunities

PURPOSE OF REVIEW

Invasive aspergillosis is a worldwide disease that primarily affects immune-compromised patients, agricultural workers with corneal abrasions, individuals with structural lung disease, and patients with primary immune deficiency. The critical function of the immune system is to prevent the germination of airborne conidia into tissue-invasive hyphae. This review covers recent advances that shape our understanding of anti-Aspergillus immunity at the molecular and cellular level.

RECENT FINDINGS

Host defense against conidia and hyphae occurs via distinct molecular mechanisms that involve intracellular and extracellular killing pathways, as well as cooperation between different myeloid cell subsets. The strength and efficacy of the host response is shaped by the tissue microenvironment. In preclinical models of disease, host immune augmentation strategies have yielded benefits, yet translating these insights into therapeutic strategies in humans remains challenging.

SUMMARY

Although advances in early diagnostic strategies and in antifungal drugs have ameliorated clinical outcomes of invasive aspergillosis, further improvements depend on gaining deeper insight into and translating advances in anti-Aspergillus immunity.

Rodent Models of Invasive Aspergillosis due to Aspergillus fumigatus: Still a Long Path toward Standardization

Invasive aspergillosis has been studied in laboratory by the means of plethora of distinct animal models. They were developed to address pathophysiology, therapy, diagnosis, or miscellaneous other concerns associated. However, there are great discrepancies regarding all the experimental variables of animal models, and a thorough focus on them is needed. This systematic review completed a comprehensive bibliographic analysis specifically-based on the technical features of rodent models infected with Aspergillus fumigatus. Out the 800 articles reviewed, it was shown that mice remained the preferred model (85.8% of the referenced reports), above rats (10.8%), and guinea pigs (3.8%). Three quarters of the models involved immunocompromised status, mainly by steroids (44.4%) and/or alkylating drugs (42.9%), but only 27.7% were reported to receive antibiotic prophylaxis to prevent from bacterial infection. Injection of spores (30.0%) and inhalation/deposition into respiratory airways (66.9%) were the most used routes for experimental inoculation. Overall, more than 230 distinct A. fumigatus strains were used in models. Of all the published studies, 18.4% did not mention usage of any diagnostic tool, like histopathology or mycological culture, to control correct implementation of the disease and to measure outcome. In light of these findings, a consensus discussion should be engaged to establish a minimum standardization, although this may not be consistently suitable for addressing all the specific aspects of invasive aspergillosis.

Granulocyte transfusions in critically ill children with prolonged neutropenia: side effects and survival rates from a single-center analysis

Granulocyte transfusions for neutropenic patients have been used for over 40 years, although effectiveness, indications, and both patient and donor safety remain debated. This single-center study assessed the side effects, clinical course, and survival of granulocyte transfusions in critically ill pediatric patients, with underlying hemato-oncological disorders, prolonged neutropenia, and proven or suspected severe infection. Donor-specific side effects and influence of donor-specific characteristics on patient outcome were also investigated. A median of 4.02 × 10(10) cells was collected from 39 healthy donors for 118 granulocyte concentrates. Donors reported no significant side effects. Complications for patients were frequent but mostly minor and included vomiting, hypotension, and dyspnea. In one episode of life-threatening dyspnea, association with the granulocyte transfusion could not be ruled out. Overall survival on day 100 was 61.9 %. Patients received a median of 0.13 × 10(10) cells per kg body weight. Doses above this median were associated with a significantly better survival. Lower patient weight and age-/sex-adjusted weight were also associated with better survival.

CONCLUSION

Granulocyte mobilization and collection is a safe practice. Transfusions are well tolerated in critically ill patients. Patient weight and transfused cells per kg bodyweight are major determinants of survival in pediatric patients.

WHAT IS KNOWN

• Granulocyte transfusions for neutropenic patients have been used for over 40 years • The effectiveness of the technique remains controversial • Patient and donor safety remain debated • New mobilization protocols generate higher yields of granulocytes What is new: • Granulocyte collection can safely be performed • Granulocytes can safely be administered to patients • Lower patient weight and age-/sex-adjusted weight are associated with better survival rates • Patients receiving above 0.13 × 10 (10) cells per kg body weight had an excellent outcome • Further standardized, prospective studies are warranted.

Practice Guidelines for the Diagnosis and Management of Aspergillosis: 2016 Update by the Infectious Diseases Society of America

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.