Translational Research: Host-Pathogen Interactions in Patient Fungal Diseases

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

Improving treatment of cryptococcal meningitis. Cryptococcus is the most common cause of non-viral meningitis in the U.S. and the disease continues to have an attributable mortality of approximately 30% despite therapy. We have recruited approximately almost 200 patients with both meningoencephalitis and pulmonary disease. The protocol utilizes the latest in immunological and genetic methods and is divided in two parts: 1) to characterize and apply novel therapeutics to the acute phase of the disease to improve outcomes and 2) identify genetic and immunological risk factors involved in susceptibility to the disease during the convalescence phase. Previously, we reported 15 patients treated with pulse corticosteroid-taper (PCT) therapy that has resulted in reducing the mortality approximately 10-fold to less than 2%. We have extended these studies by seeking to identify potential steroid-sparing therapy. Typically, these studies would involve lengthy, hypothesis-based testing and tedious and time-consuming therapeutic trials, the latter of which expose patients to potentially toxic but ineffective therapies. We followed this approach which identified a potential role of the IL6 receptor antagonist tocilizumab but found it difficult to utilize due to its intravenous route of administration and limited efficacy. Thus, to expedite this search, we utilized an unbiased approach of ‘pathway-instructed therapeutics’ that utilized nanostring analysis of over 700 genes expressed during human post-infectious inflammatory response syndrome from cryptococcal meningitis patients prior to therapy and utilized upstream analysis which identified the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway as prominent in the pathway. We then utilized mouse models to validate in pre-clinical studies the JAK/STAT inhibitor ruxolitinib (in our associated funded project). We then advanced the drug to clinical treatment of 6 patients and demonstrated clinical efficacy, safety and tolerability in a small cohort of patients refractory to corticosteroid therapy. We have now treated an additional 5 patients with ruxolitinib and are preparing a proposal to a company for the study of a more specific JAK/STAT inhibitor as a potential steroid-sparing therapy in a randomized/controlled study. Previously we had conducted preclinical trials of an oral amphotericin b preparation and demonstrated efficacy of a regimen in combination with flucytosine. In the present period, we completed studies in collaboration with David Boulware at the Univ Minnesotta in Uganda, where 60 patients were treated with the oral regimen. These studies demonstrated equal efficacy with the intravenous preparation but without any of the toxicity of the intravenous preparation. As such, the oral amphotericin preparation represents a game changing therapy in developing countries where the ability to give and monitor intravenous therapy with amphotericin B is extremely limiting. Host susceptibility to cryptococcal disease in previously healthy individuals. a) Autoantibody to host cytokines: Previously, in collaboration with S. Browne of LCID, we had identified patients with C. gattii, a related form of Cryptococcus with an autoantibody to the macrophage stimulator granulocyte-monocyte stimulating factor, GM-CSF. We are presently studying the regulatory pathway of GM-CSF signaling and have found that autophagy plays a key role in concert with the macrophage inflammasome pathway, suggesting novel mechanisms for intervention. We have now identified a mutant allele in multiple patients that result in a cellular defect in GMCSF and are investigating the role of this mutation in multiple patients. We have constructed relevant iPS and CRISPR/cas9-corrected patient cells from 3 patients and are in the process of importing a mouse KO line that can help facilitate these studies. Genetic Defects: We have currently performed whole exome sequencing on 180 patients with CM disease and have identified several new susceptibility genes using mouse modeling. We have also provided additional characterization of the multi-center cohort of non-HIV associated cryptococcal meningitis as part of a collaborative project with Johns Hopkins including the results of magnetic resonance imaging. We also described the role of antigen titers in cryptococcal meningitis and potential factors that could influence the rates of their decline in patients.