No abstract

Coccidioidomycosis is a fungal, respiratory disease caused by Coccidioides immitis and Coccidioides posadasii. The host immune responses that define disease outcome during infection are largely unknown, although T helper responses are required. Adaptive immunity is influenced by innate immunity as antigen-presenting cells activate and educate adaptive responses. Macrophage and dendritic cell (DC) recognition of pathogen surface molecules are critical for Coccidioides clearance. We characterize the broad innate immune responses to Coccidioides by analyzing macrophage and dendritic cell responses to Coccidioides arthroconidia using avirulent, vaccine Coccidioides strain NR-166 (Δcts2/Δard1/Δcts3), developed from parental virulent strain C735. We developed a novel flow cytometry-based method to analyze macrophage phagocytosis to complement traditional image-scoring methods. Our study found that macrophage polarization is blocked at M0 phase and activation reduced, while DCs polarize into proinflammatory DC1s, but not anti-inflammatory DC2, following interaction with Coccidioides. However, DCs exhibit a contact-dependent reduced activation to Coccidioides as defined by co-expression of MHC-II and CD86. In vivo, only modest DC1/DC2 recruitment and activation was observed with avirulent Coccidioides infection. In conclusion, the vaccine Coccidioides strain recruited a mixed DC population in vivo, while in vitro data suggest active innate immune cell inhibition by Coccidioides.

Between 70 and 80% of Valley fever patients receive one or more rounds of antibiotic treatment prior to accurate diagnosis with coccidioidomycosis. Antibiotic treatment and infection (bacterial, viral, fungal, parasitic) often have negative implications on host microbial dysbiosis, immunological responses, and disease outcome. These perturbations have focused on the impact of gut dysbiosis on pulmonary disease instead of the implications of direct lung dysbiosis. However, recent work highlights a need to establish the direct effects of the lung microbiota on infection outcome. Cystic fibrosis, chronic obstructive pulmonary disease, COVID-19, and M. tuberculosis studies suggest that surveying the lung microbiota composition can serve as a predictive factor of disease severity and could inform treatment options. In addition to traditional treatment options, probiotics can reverse perturbation-induced repercussions on disease outcomes. The purpose of this review is to speculate on the effects perturbations of the host microbiome can have on coccidioidomycosis progression. To do this, parallels are drawn to aa compilation of other host microbiome infection studies.

It has long been thought that the lung is a sterile environment; however, recent studies revealed that healthy lungs are colonized by bacteria, fungi, and viruses. Coccidioidomycosis, also known as Valley fever, is a lung infection caused by the fungal species Coccidioides. Because of poor testing strategies 60–80% of patients are treated with antibiotics prior to accurate diagnosis of coccidioidomycosis. This potentially depletes bacteria with symbiotic relationships within the lung microenvironment and promotes susceptibility to invasion by Coccidioides. Coccidioides immitis is a dimorphic fungal pathogens whose fungal life cycle alternates between the saprophytic phase (soil mycelia) and parasitic phase (tissue infecting spherules). Natural microbial antagonists that inhibit soil Coccidioides immitis have been identified; Bacillus subtilis displays antifungal activity against Coccidioides growth through a clear zone of inhibition between fungi and bacteria. Whether these findings hold true in the host phase of the Coccidioides life cycle is unknown but have major implications for patient treatment. Our preliminary data suggest that host microbiome inhibits Coccidioides growth, and antibiotic treatment shifts or depletes the lung microbiome allowing a niche for Coccidioides growth. We are also exploring how this interface between the lung, Coccidioides, and the microbiome influences host innate and adaptive immune responses. Furthermore, these findings could shape the way physicians assess prescription of antibiotics prior to fungal diagnosis.

Valley fever is a respiratory disease caused by the fungal pathogen Coccidioides. Very little is known about how the fungus interacts with the immune system and the lung microenvironment, hampering vaccine and therapy development. There is a critical need to identify which immune cells are interacting with the fungus in the lungs and how these cells control infection. Granulomas form within the lung to control infection, but the formation, maintenance, and molecular and immune players in these processes are largely unexplored. Granuloma cell mass can be identified in X-rays and MRI scans only to be misdiagnosed for tumors, until a lung biopsy is analyzed. To investigate immune cells present in Coccidioides granulomas, we utilized tissue immunohistochemistry via fixed-formalin paraffin-embedded (FFPE) and fresh frozen embedded samples to assess immune cell and Coccidioides interactions. Various labeling methods have been investigated using infected mouse lungs to optimize procedures before switching to patient samples. Hematoxylin and eosin (H&E) staining combined with periodic acid–Schiff (PAS) identifies Coccidioides spread within the lung following fungal inhalation in mice. Lung imaging challenges include the presence of endogenous peroxidases that cause non-specific antibody binding. Antigen retrieval following paraffin embedding, have now been optimized to fit the lung and specific to the antibody that is being used. Here we highlight various troubleshooting methods with successful immunofluorescence FFPE lung imaging. Supported by University of California Office of the President grant VFR-19-633952 & R21