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Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans
Published on: December 19, 2014
Protective immunity against cryptococcus neoformans infection
1University of Texas at San Antonio, San Antonio, TX 78229, USA. schop@lonestar.utsa.edu
Abstract:
Cryptococcus neoformans, the etiological agent of cryptococcosis, is an occasional opportunistic fungal pathogen of immune competent individuals. However, it is a relatively frequent cause of life-threatening meningoencephalitis and pulmonary infections in immunosuppressed hosts and is a leading mycological cause of morbidity and mortality among patients with AIDS in most parts of the world. The lack of an effective fungicidal regimen and the development of antifungal resistant strains suggest that continued investigation is necessary to devise immunotherapeutic strategies, drug targets and/or vaccines to combat C. neoformans infections. Until recently, cryptococcal virulence factors such as its polysaccharide capsule, macrophage parasitism, and its ability to induce an ineffective antibody mediated immune (AMI) response along with a non-protective type II (Th2) cell-mediated immune response have thwarted efforts to induce complete protective immunity against a lethal cryptococcal strain in murine models. The presence of C. neoformans antibodies in adult human serum suggests that immune competent individuals have difficulty resolving an early cryptococcal infection allowing for the establishment of a subclinical chronic infection. Recent studies have shown that pro-inflammatory cytokines, specifically interferon-g (IFN-gamma), associated with type I (Th1) cell-mediated immunity can successfully drive cell-mediated immune (CMI) responses to produce protective immunity to a second experimental C. neoformans infection in mice. This review will evaluate the intricacies of the host-cryptococcal interaction and discuss recent developments in C. neoformans research and the potential for human vaccines and/or drug therapies.
Insights
Cryptococcus neoformans causes severe infections, especially in immunocompromised individuals. Research highlights interferon-gamma and Th1 immunity as key to developing effective vaccines and therapies against this fungal pathogen.
Area of Science:
- Mycology
- Immunology
- Infectious Diseases
Background:
- Cryptococcus neoformans is an opportunistic fungal pathogen causing cryptococcosis, a major cause of mortality in AIDS patients.
- It leads to life-threatening meningoencephalitis and pulmonary infections, particularly in immunosuppressed individuals.
- Existing treatments are limited by resistance and lack of effective fungicidal regimens.
Purpose of the Study:
- To review host-cryptococcal interactions and recent advancements in combating C. neoformans infections.
- To explore potential immunotherapeutic strategies, drug targets, and vaccines.
- To evaluate the role of cell-mediated immunity in protective responses.
Main Methods:
- Review of existing literature on C. neoformans virulence factors and host immune responses.
- Analysis of studies investigating the efficacy of pro-inflammatory cytokines, like interferon-gamma (IFN-gamma).
- Evaluation of murine models for assessing protective immunity against C. neoformans.
Main Results:
- Cryptococcal virulence factors (capsule, macrophage parasitism) and ineffective immune responses (Th2, AMI) have hindered immunity development.
- Pro-inflammatory cytokines, specifically IFN-gamma associated with Th1 immunity, show promise in driving protective cell-mediated immunity (CMI).
- Immune-competent individuals may harbor subclinical chronic infections, indicating challenges in resolving C. neoformans.
Conclusions:
- Developing effective vaccines and therapies against C. neoformans requires a deeper understanding of host-pathogen interactions.
- Type 1 (Th1) cell-mediated immunity, induced by IFN-gamma, offers a promising avenue for protective immunity.
- Further research is crucial for devising novel immunotherapeutic strategies and drug targets to combat cryptococcosis.
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