Unmasking Cryptococcal Meningitis Immune Reconstitution Inflammatory Syndrome due to Granulocyte Colony-Stimulating Factor Use in a Patient with a Poorly Differentiated Germ Cell Neoplasm

Cerebrospinal fluid cytokine and chemokine patterns correlate with prognosis of HIV-uninfected cryptococcal meningitis: A prospective observational study

The cerebrospinal fluid (CSF) immune responses in HIV-uninfected cryptococcal meningitis (CM) have not been well studied. In this study, we aimed to explore the phenotype of CSF immune response during the course of disease and to examine relationships between phenotypes and disease severity. We profiled the CSF immune response in 128 HIV-uninfected CM and 30 pulmonary cryptococcosis patients using a 27-plex Luminex cytokine kit. Principal component analyses (PCA) and logistic regression model were performed. Concentrations of 23 out of 27 cytokines and chemokines in baseline CSF were significantly elevated in CM patients compared with pulmonary cryptococcosis cases. In CM patients with Cryptococcus neoformans infection, IL-1ra, IL-9, and VEGF were significantly elevated in immunocompetent cases. Cytokine levels usually reached peaks within the first 2 weeks of antifungal treatment and gradually decreased over time. PCA demonstrated a co-correlated CSF cytokine and chemokine response consisting of Th1, Th2, and Th17 type cytokines. Prognostic analysis showed that higher scores for the PCs loading pro-inflammatory cytokines, IFN-γ, TNF-α, and IL-12; and anti-inflammatory cytokine, IL-4; and chemokines, Eotaxin, FGF-basis, and PDGF-bb; as well as lower scores for the PCs loading RANTES were associated with disease severity, as defined by a Glasgow Coma Scale of <15 or death. In conclusion, combined inflammatory responses in CSF involving both pro- and anti-inflammatory cytokines and chemokines are upregulated in HIV-uninfected CM, and associated with disease severity.

Efficacy of Oral Encochleated Amphotericin B in a Mouse Model of Cryptococcal Meningoencephalitis

Cryptococcus neoformans is an encapsulated yeast responsible for approximately a quarter of a million deaths worldwide annually despite therapy, and upwards of 11% of HIV/AIDS-related deaths, rivaling the impact of tuberculosis and malaria. However, the most effective antifungal agent, amphotericin B, requires intravenous delivery and has significant renal and hematopoietic toxicity, making it difficult to utilize, especially in resource-limited settings. The present studies describe a new nanoparticle crystal encapsulated formulation of amphotericin B known as encochleated amphotericin B (CAmB) that seeks to provide an oral formulation that is low in toxicity and cost. Using a 3-day delayed model of murine cryptococcal meningoencephalitis and a large inoculum of a highly virulent strain of serotype A C. neoformans, CAmB, in combination with flucytosine, was found to have efficacy equivalent to parental amphotericin B deoxycholate with flucytosine and superior to oral fluconazole without untoward toxicity. Transport of fluorescent CAmB particles to brain as well as significant brain levels of amphotericin drug was demonstrated in treated mice, and immunological profiles were similar to those of mice treated with conventional amphotericin B. Additional toxicity studies using a standardized rat model showed negligible toxicity after a 28-day treatment schedule. These studies thus offer the potential for an efficacious oral formulation of a known fungicidal drug against intrathecal cryptococcal disease.IMPORTANCE Cryptococcus neoformans is a significant global fungal pathogen that kills an estimated quarter of a million HIV-infected individuals yearly and has poor outcomes despite therapy. The most effective therapy, amphotericin B, is highly effective in killing the fungus but is available only in highly toxic, intravenous formulations that are unavailable in most of the developing world, where cryptococcal disease in most prevalent. For example, in Ethiopia, reliance on the orally available antifungal fluconazole results in high mortality, even when initiated as preemptive therapy at the time of HIV diagnosis. Thus, alternative agents could result in significant saving of lives. Toward this end, the present work describes the development of a new formulation of amphotericin B (CAmB) that encapsulates the drug as a crystal lipid nanoparticle that facilitates oral absorption and prevents toxicity. Successful oral absorption of the drug was demonstrated in a mouse model that, in combination with the antifungal flucytosine, provided efficacy equal to a parental preparation of amphotericin B plus flucytosine. These studies demonstrate the potential for CAmB in combination with flucytosine to provide an effective oral formulation of a well-known, potent fungicidal drug combination.

Immunology of Cryptococcal Infections: Developing a Rational Approach to Patient Therapy

Cryptococcal meningoencephalitis is responsible for upwards of 15% of HIV-related deaths worldwide and is currently the most common cause of non-viral meningitis in the US, affecting both previously healthy and people with immune suppression caused by cancer chemotherapy, transplantation, and biologic therapies. Despite a continued 30-50% attributable mortality, recommended therapeutic strategies have remained largely unchanged since the 1950s. Recent murine models and human studies examining the role of the immune system in both susceptibility to the infection as well as host damage have begun to influence patient care decisions. The Damage Framework Response, originally proposed in 1999, was recently used to discuss dichotomous etiologies of host damage in cryptococcal disease. These include patients suffering microbiological damage with low host immunity (especially those immunosuppressed with HIV) and those having low (live) microbiological burden but high immune-mediated damage (HIV-related immune reconstitution syndrome and non-HIV-related postinfectious inflammatory response syndrome). Cryptococcal disease in previously healthy hosts, albeit rare, has been known for a long time. Immunophenotyping and dendritic cell-T cell signaling studies on cerebral spinal fluid of these rare patients reveal immune capacity for recognition and T-cell activation pathways including increased levels of HLA-DR and CD56. However, despite effective T-cell signals, brain biopsy and autopsy specimens demonstrated an M2 alternative macrophage polarization and poor phagocytosis of fungal cells. These studies expand the paradigm for cryptococcal disease susceptibility to include a prominent role for immune-mediated damage and suggest a need for careful individual consideration of immune activation during therapy of cryptococcal disease in diverse hosts.

Recent advances in AIDS-related cryptococcal meningitis treatment with an emphasis on resource limited settings

INTRODUCTION

Recent advances in the treatment and prevention of cryptococcal meningitis have the potential to decrease AIDS-related deaths. Areas covered: Targeted screening for asymptomatic cryptococcal antigenemia in persons with AIDS is a cost effective method for reducing early mortality in patients on antiretroviral therapy. For persons with symptomatic cryptococcal meningitis, optimal initial management with amphotericin and flucytosine improves survival compared to alternative therapies; however, amphotsericin is difficult to administer and flucytosine has not been available in middle or low income countries, where cryptococcal meningitis is most prevalent. Expert commentary: Improved care for cryptococcal meningitis patients in resource-limited settings is possible, and new treatment possibilities are emerging.

Fighting the Monster: Applying the Host Damage Framework to Human Central Nervous System Infections

The host damage-response framework states that microbial pathogenesis is a product of microbial virulence factors and collateral damage from host immune responses. Immune-mediated host damage is particularly important within the size-restricted central nervous system (CNS), where immune responses may exacerbate cerebral edema and neurological damage, leading to coma and death. In this review, we compare human host and therapeutic responses in representative nonviral generalized CNS infections that induce archetypal host damage responses: cryptococcal menigoencephalitis and tuberculous meningitis in HIV-infected and non-HIV-infected patients, pneumococcal meningitis, and cerebral malaria. Consideration of the underlying patterns of host responses provides critical insights into host damage and may suggest tailored adjunctive therapeutics to improve disease outcome.